88

PHN II

CC VI KHUN GY BNH THNG GP CC CU KHUN GY BNHMc tiu hc tp 1. Trnh by c mt s tnh cht vi khun hc ca mt s cu khun gy bnh. 2. Nu c kh nng gy bnh ca cc cu khun ny. 3. Trnh by c mt s phng php chn on vi khun hc i vi cc cu khun gy bnh. Cu khun gy bnh bao gm T cu, Lin cu, Ph cu v Neisseria. l nhng vi khun hnh cu v c gi chung l cu khun sinh m. Tr Neisseria, cc cu khun sinh m u Gram dng.

I. T CU (STAPHYLOCOCCI)T cu tm thy khp ni v c th phn lp t khng kh, bi, thc phm, c th ngi v ng vt. T cu l thnh vin ca khun ch da hoc nim mc t hu ngi. C 3 loi t cu c kh nng gy bnh nhim trng ngi: Staphylococcus aureus (S.aureus: t cu vng) c xem l t cu gy bnh, Staphylococcus epidermidis (S. epidermidis) v Staphylococcus saprophyticus (S. saprophyticus) thng xem nh l t cu khng gy bnh; tuy nhin 2 loi sau cng c th gy nhim khun ng tit niu hoc nhim khun trong phu thut tim, trong thng tnh mch. Ni dung bi ny tp trung vo S. aureus. 1.c im sinh vt hc 1.1. Hnh thi Vi khun hnh cu hoc hnh thun, ng knh 0,8-1m, canh thang thng hp thnh tng cm nh chm nho, hnh thc tp hp ny do vi khun phn bo theo nhiu chiu trong khng gian. Trong bnh phm vi khun hp tng i hoc m nh. Vi khun bt mu Gram (Gram dng). Vi khun khng di ng, khng sinh nha bo, thng khng c v. 1.2. Tnh cht nui cy Vi khun pht trin d dng mi trng thng thng, hiu kh hoc k kh ty , mc tt 370C nhng to sc t tt 20 0C. canh thang sau 5 - 6 gi lm c mi trng, sau 24 gi lm c r. mi trng c, khun lc trn li, bng lng, ng nh c th c mu vng m, mu vng cam hoc mu trng, tng i ln sau 24 gi. Nhng chng khc nhau lm tan mu nhng mc khc nhau, thch mu typ tan mu thng c quan st xung quanh khun lc. 1.3. Tnh cht sinh ha v khng T cu c h thng enzyme phong ph, nhng enzyme c dng trong chn on l: catalase (phn bit vi lin cu), S. aureus c coagulase (tiu chun quan trng phn bit t cu vng vi cc t cu khc). T cu ln men chm nhiu loi ng, to axt nhng khng sinh hi, S. aureus ln men ng mannt. T cu tng i chu nhit v thuc st khun hn nhng vi khun khc, chu kh v c th sng mi trng nng NaCl cao (9%), nhy cm thay i vi khng sinh, nhiu chng khng vi penicillin v cc khng sinh khc. 1.4. Cu trc khng nguyn Vch t bo vi khun cha khng nguyn polysaccharid, khng nguyn protein A b mt. Ngi ta c th cn c vo cc khng nguyn trn chia t cu thnh nhm, tuy nhin phn ng huyt thanh khng c gi tr trong chn on vi khun.

89

Cn c vo s nhy cm vi phag, ngi ta chia t cu thnh typ phag. Nhng b phage cho php xp loi phn ln cc chng t cu thnh 4 nhm phag chnh. nh typ phage t cu c gi tr v dch t hc v chn on. 1.5. Cc c t v enzyme Kh nng gy bnh ca t cu l do vi khun pht trin v lan trn rng ri trong m cng nh to thnh nhiu c t v enzyme. 1.5.1. Hemolysin: c 4 loi hemolysin c xc nh l , , v . Mt chng t cu c th to thnh nhiu hn mt loi hemolysin. l nhng phm vt bn cht protein gy tan mu nhng tc ng khc nhau trn nhng hng cu khc nhau. Chng c tnh sinh khng. Mt vi loi hemolysin gy hoi t da ti ch v git cht sc vt th nghim. 1.5.2. Leucocidin: l nhn t git cht bch cu ca nhiu loi ng vt, bn cht protein, khng chu nhit. T cu gy bnh c th b thc bo nh t cu khng gy bnh nhng li c kh nng pht trin bn trong bch cu. 1.5.3. Coagulase: lm ng huyt tng ngi hoc th chng ng vi citrat natri hoc oxalat natri. Coagulase lm dnh t huyt vo b mt vi khun v do hnh nh cn tr s thc bo. Tt c cc chng S. aureus u c coagulase dng tnh. 1.5.4. Hyaluronidase: thy phn axit hyaluronic ca m lin kt, gip vi khun lan trn vo m. 1.5.5. -lactamase: s khng penicillin ca t cu vng l do a s t cu vng sn xut c enzyme -lactamase. Ngoi ra, t cu cn c nhng enzyme khc nh staphylokinase l mt fibrinolysin lm tan t huyt, nuclease, lipase. 1.5.6. c t rut: do mt s chng t cu to thnh, c bit lc pht trin nng CO2 cao (30%) v mi trng c va. N khng s un si trong 30 pht cng nh tc ng ca enzyme rut. C 5 typ huyt thanh A, B, C, D, E; typ A, B thng gy ng c thc n. 1.5.7. c t gy hi chng shock nhim trng (Toxic schock syndrome toxin: TSST): thng gp nhng ph n c kinh nguyt dng bng bng dy, bn hoc nhng ngi b nhim trng vt thng. C ch gy shock ca n tng t vi ni c t. 1.5.8. Exfoliatin toxin hay epidermolitic toxin: l mt ngoi c t, gy nn hi chng phng rp v chc l da (Scaded skin syndrome) tr em. 85% cc chng t cu vng thuc loi phage nhm II to c t ny. N gm 2 loi A v B, u l polypeptid, loi A bn vng vi nhit 100 0C/20pht, cn loi B th khng. C th xc nh chng bng k thut min dch (nh ELISA hoc RIA hay min dch khuch tn). Khng th c hiu c tc dng trung ho c t ny. 1.5.9. Alpha toxin: bn cht protein, gy tan cc bch cu a nhn v tiu cu, t gy ra p xe, hoi t da v tan mu. c t c tnh khng nguyn nhng khng th ca n khng c tc dng chng nhim khun. 2. Kh nng gy bnh ng xm nhp l da (gc chn lng, ch b thng) v nim mc. T cu khng gy nn mt chng bnh nht nh nhng thng lm pht sinh nhiu hnh thc nhim khun khc nhau. T cu thng gy nn nhng im nung m da, nim mc nhng c th xm nhp vo nhng c quan khc nhau. S nhim trng xy ra nhng c th khng st km nh gi yu, tr cn b, bnh i tho ng. 2.1. Cc nhim trng da v nung m su L mt hnh thc c bit, nng l inh ru, tip n l chc l, vim ty xng, vim phi mng phi, vim mng ngoi tim, vim mng no. 2.2. Nhim trng huyt

90

T nhng im nung m, vi khun c th i vo mu v gy nn nhim trng huyt. Nhim trng huyt do t cu l mt bnh thng gp bnh vin, thng xy ra ngi c sc khng gim st. 2.3. Vim rut cp tnh Thng gp cc bnh nhn ung khng sinh c khng khun ph rng, khng sinh hy dit nhng vi khun bnh thng rut, lm pht trin chng t cu sinh c t rut v gy nn chng bnh. 2.4. Ng c thc n Do t cu sinh c t rut c bit typ huyt thanh A v B gy nn. Chng bnh c nhng c im: thi gian bnh ngn (1-8 gi), bun nn d di, nn, au bng, a chy, khng st, bnh phc trong vng 24 gi. 2.5. Hi chng da phng rp (Scalded skin syndrom) Mt s chng t cu vng tit c t exfoliatin, gy vim da hoi t v phng rp. Bnh ny thng gp tr mi v tin lng xu. 2.6. Hi chng shock nhim c (Toxic shock syndrome) Thng gp nhng ph n c kinh nguyt dng bng v sinh dy, bn, b nhim vi khun t cu vng. Bnh khu tr m o v cn nguyn l t cu vng, lin quan n c t gy hi chng shock nhim trng, cy mu khng tm thy t cu vng. 3. Chn on vi khun Bnh phm l m, mu, m gii, phn, nc no ty ty theo chng bnh. Phn lp thch mu, canh thang hoc thch Chapman. Xc nh nh hnh thi knh hin vi v tnh cht sinh ha. T cu c xem nh S. aureus nh 4 tiu chun : sc t vng, tan mu, ln men ng mannit, to thnh coagulase. Trong 2 tiu chun coagulase v ln men ng mannit l quan trng nht, ch c th thiu mt trong 2 tiu chun ch khng th thiu c 2. Phn ng huyt thanh khng c gi tr chn on vi khun. Ngi ta nh typ t cu bng phag. Nh nhng phag chnh c hiu ngi ta xp t cu vo mt trong 4 nhm phag chnh (I, II, III v IV). T cu thuc nhm no th b ly gii bi mt hoc nhiu phag trong nhm . nh typ phag c gi tr v dch t hc. 4. Phng nga v iu tr 4.1. Phng nga Ngun t cu trong thin nhin l ngi. S ly nhim t ngi ny sang ngi khc l do tip xc trc tip hoc qua khng kh. Nhng ngi lnh mang trng c khuyn co khng nn lm vic phng sinh, phng tr s sinh, phng m hoc cc x nghip thc phm. 4.2. iu tr Nhiu chng T cu khng vi nhiu khng sinh nht l penicillin nn cn lm khng sinh . C trng hp s dng vaccine bn thn v vaccine tr liu c kt qu.

II. LIN CU (STREPTOCOCCI)Lin cu l nhng cu khun xp thnh hnh chui, phn b rng ri trong thin nhin. Mt vi loi l thnh vin ca khun ch bnh thng ngi. Mt vi loi gy nn nhng chng bnh quan trng. 1. c im sinh vt hc

91

1.1. Hnh th Vi khun hnh cu, ng knh1 m, Gram dng, thng xp thnh chui di ngn khc nhau, c th ng i hoc ring l. Vi khun khng c lng, khng to nha bo. Nhiu chng thuc nhm A v C to v axit hyaluronic. 1.2. Tnh cht nui cy Lin cu l nhng vi khun hiu k kh ty , ch pht trin tt mi trng c mu hoc c cc dch ca c th khc. Nhng chng gy bnh thng i hi nhiu yu t pht trin. Phn ln lin cu tan mu gy bnh pht trin tt 37 0C. Cc lin cu rut pht trin tt khong nhit t 10 n 45 0C. mi trng lng vi khun d to thnh cc chui, sau 24 gi canh thang vn trong v c nhng ht, nhng cm dnh vo thnh ng sau lng xung y ng. thch mu, khun lc nh trn li mu hi xm, bng hoc m c. Nhng chng ca lin cu A c v to nn nhng khun lc ly nhy. Lin cu gy nn 3 typ tan mu: tan mu ca lin cu tan mu A, tan mu ca lin cu viridans v tan mu ca lin cu khng tan mu. 1.3. Tnh cht sinh vt ha hc Lin cu khng c catalase (khc vi t cu). Lin cu A c bit nhy cm vi bacitracin. phn bit lin cu v ph cu, ngi ta da vo kh nng ca lin cu khng vi mt hoc mui mt hoc vi optochin trong khi ph cu th ngc li. 1.4. Cu trc khng nguyn Lin cu c cu trc khng nguyn phc tp. 1.4.1. Khng nguyn v axit hyaluronic Tm thy v mt s lin cu A, khng c tnh cht sinh khng. 1.4.2. Khng nguyn carbohydrat C c hiu nhm y l khng nguyn nm vch t bo vi khun. Da vo khng nguyn carbohydrat C, Lancefield chia lin cu tan mu thnh nhiu nhm huyt thanh t A n O. Phn ln nhng lin cu gy bnh ngi thuc nhm A, tuy nhin nhng chng nhm B, C v G cng tm thy trong nhim trng h hp, nhim trng huyt v vim mng trong tim. 1.4.3. Khng nguyn M c hiu typ Khng nguyn M cng nm vch t bo vi khun, l protein M lin h n Lin cu A v tm thy nhng vi khun to thnh khun lc m c hoc ly nhy. N cn tr s thc bo. Cn c vo khng nguyn ny ngi ta chia lin cu A thnh nhiu typ, hin c trn 55 typ trong typ 12 gy bnh rt nghim trng. 1.4.4. Phm vt T Bn cht protein, khng lin quan n c lc, thu c bng cch thy phn ph hy protein M. Phm vt T cho php phn bit mt s typ lin cu. 1.5. Cc enzyme v c t Lin cu to thnh nhiu enzyme v c t. 1.5.1. Streptokinase Tm thy nhiu chng lin cu tan mu . N bin i plasminogen thnh plasmin c kh nng thy phn t huyt v nhng protein khc. Streptokinase kch ng s to thnh khng th khng streptokinase (ASK) v enzyme ny c s dng iu tr nhng tr ngi do ng mu gy nn. 1.5.2. Streptodornase Enzyme ny c kh nng thy phn DNA do lm lng m. Mt ch phm cha streptokinase v streptodornase c dng lm lng dch ngoi tit c, gip cho khng sinh n ch nhim trng v c s dung trong lam sng iu tr vim m mng phi. 1.5.3. Hyaluronidase :

92

Thy phn axit hyaluronic, cht cn bn ca m lin kt v gip cho vi khun bnh trng su rng vo cc m. 1.5.4. Dung huyt t : Lin cu tan mu to thnh 2 loi dung huyt t : - Streptolysin O: c hot tnh tan mu trng thi kh oxy, nhng nhanh chng b bt hot trng thi oxy ha. C tnh cht sinh khng mnh, n kch ng to thnh khng th khng streptolysin O (ASO). Trong chn on bnh thp khp cp v vim cu thn cp, vic nh hiu gi ASO rt c gi tr khng nh nhim lin cu. - Streptolysin S: chu trch nhim v s hnh thnh vng tan mu xung quanh khun lc thch mu, khng b bt hot bi oxy v khng c tnh sinh khng. 1.5.5. c t sinh : Gy pht ban trong bnh tinh hng nhit, thng tm thy lin cu A. 2. Phn loi lin cu Da vo kh nng lm tan mu, s khng vi tc nhn l ha v th nghim sinh ha ngi ta chia lin cu thnh 4 nhm : 2.1. Lin cu tan mu To dung huyt t ha tan chu trch nhim v typ tan mu thch mu. Chng to thnh cacbohydrat C c hiu nhm. Da vo cacbohydrat C ngi ta chia lin cu tan mu thnh nhiu nhm t A n O. 2.2. Lin cu viridans Khng gy tan mu thch mu. Nhiu loi gy tan mu , nhng cng c nhng loi khng tc dng vi mu. Lin cu viridans khng to thnh cacbohydrat C. Chng l thnh phn ch yu ca khun ch ng h hp v ch gy bnh lc xm nhim van tim khng bnh thng hoc mng no hoc ng tiu. 2.3. Lin cu rut To thnh cacbohydrat C c hiu nhm D, pht trin tt nhit t 1045oC, nng 6,5% NaCl v thch 40% mui mt. Kh nng tan mu thay i. Chng c tm thy khun ch bnh thng rut v c th gy bnh lc xm nhim m, mu, ng tiu hoc mng no. 2.4. Lin cu lactic Tan mu thay i, pht trin thch cha 40% mt nhng khng pht trin o 45 C, khng gy bnh, thng tm thy trong sa. 3. Kh nng gy bnh Trong cc lin cu th lin cu nhm A l nhm lin cu gy bnh nhiu nht ngi. Chng gy nn nhng bnh cnh sau : 3.1. Cc nhim khun ti ch Nh vim hng, vim t hu, chc l, vim qung ngi ln, nhim khun cc vt thng. 3.2. Cc nhim khun th pht Nh vim mng trong tim cp, st hu sn hoc nhim khun huyt m im xut pht l t da, t cung hoc t vng t hu. 3.3. Bnh tinh hng nhit Thng gp tr em trn 2 tui cc nc n i. 3.4. Cc di chng ca nhim lin cu A c im ca nhim khun Lin cu A l s xut hin cc di chng 2-3 tun l sau bnh lin cu, c bit l sau vim hng. Di chng c th l vim cu thn cp hoc thp khp cp. 3.4.1. Vim cu thn cp Xy ra mt s ngi 1-3 tun l sau khi nhim lin cu A, c bit l nhim cc typ 12, 4, 49 hoc 57 hng hoc da, do s tc ng ca phc hp khng nguyn-

93

khng th ln mng c bn ca tiu cu thn. Triu chng l tiu mu, ph thng, cao huyt p. Cc gi thuyt cho rng l do s tc ng ca khng th chng li khng nguyn vch ca lin cu nhm A phn ng cho vi mng y ca cu thn. 3.4.2. Thp khp cp L mt di chng nghim trng nht v n a n ph hy c tim v van tim. Mt vi chng lin cu A c khng nguyn mng t bo phn ng cho vi si c tim. Huyt thanh ca bnh nhn thp khp cp cha khng th phn ng vi nhng khng nguyn . Thp khp cp c xu hng tr nn nghim trng trong nhim trng ti pht. Ngoi ra, phc hp min dch globulin min dch-b th-khng nguyn ca lin cu c chng minh bng min dch hunh quang thng tn ca tiu cu thn v c tim. 4. Tnh min dch S khng vi lin cu c tnh cht c hiu typ. Ch c khng th khng M c hiu typ c kh nng chng li s nhim trng. Lin cu A c trn 55 typ huyt thanh. Nhn chung khng ngi no tr nn min dch vi tt c nhm lin cu A. Cc khng th khng Streptolysin O v khng Streptokinase khng c kh nng bo v c th. 5. Chn on vi sinh vt 5.1. Chn on trc tip Bnh phm thch hp, c th l mu, m, m gii, nc tiu, nc no ty v..v..ri nui cy ln trn cc mi trng thch hp; phn lp v nh danh vi khun da vo c im hnh th, tnh cht nui cy, tnh cht khun lc, tnh cht tan mu. Nhng chng lin cu A rt nhy cm vi bacitracin. Xc nh nhm ca lin cu tan mu nht l nhm A, B, C, G bng th nghim ng ngng kt. 5.2. Chn on gin tip Trong cc trng hp nh thp khp cp c th s dng phn ng ASO nh hiu gi ASO trong mu bnh nhn. y l mt phn ng trung ha enzyme, bnh thng hiu gi ASO < 200 n v. Trong trng hp bnh l ASO tng cao. ASK t c s dng. 6. Phng bnh v iu tr 6.1. Phng bnh Ngun nhim lin cu A l ngi, ch yu l phng bnh chung nh pht hin sm nhng nhim trng da, hng do lin cu A gy nn iu tr vi khng sinh thch hp. Cn pht hin v iu tr nhng ngi lnh mang trng phc v cc nh h sinh, nh tr, phng m. 6.2. iu tr i vi lin cu A phi iu tr sm liu lng y vi khng sinh git khun nh penicillin, erythromycin. i vi lin cu viridans, lin cu rut, cn phi hp khng sinh gia nhm lactamin v aminoglycosit nh penicillin v streptomycin hoc iu tr theo khng sinh .

III. PH CU (STREPTOCOCCUS PNEUMONIAE)Ph cu thng gp vng t hu ca ngi bnh thng vi t l kh cao (20-40%). 1. c im sinh vt hc 1.1. Hnh th Ph cu l cu khun Gram dng, hnh ngn nn, xp thnh i, 2 u ging nhau nhn vo nhau to thnh hnh mt knh hay s 8. Trong mi trng nui cy, ph cu thng xp thnh chui ngn d nhm vi lin cu. Trong bnh phm hay trong mi trng nui cy giu albumin th vi khun to v. Nui cy lu ngy mi trng nhn to th khng c v. Vi khun khng c lng, khng to nha bo. Nhng enzyme t ly gii lm cho vi khun mt mu Gram ri ly gii. 1.2. Tnh cht nui cy

94

Ph cu l vi khun hiu k kh ty , mc tt mi trng giu cht dinh dng v kh trng 5 - 10% CO2. Nhit thch hp 370C, pH 7,2 - 7,6. thch mu khun lc sau 24 gi nh, trn, b u, trong, lc u li, sau lm gia vi b cao xung quanh, to vng tan mu xung quanh khun lc. 1.3. Tnh cht sinh ha Ph cu ln men nhiu loi ng, khng sinh hi, catalase m tnh, phn ng Neufeld dng tnh (tan trong dung dch mt hay mui mt), khng mc mi trng c optochin. 1.4. Sc khng Ph cu d b git cht bi nhng cht st khun thng thng (Phenol, Cl 2Hg) v nhit (60 0C trong 30 pht). Trong qu trnh gi chng, vi khun d b gim c lc hoc bin i t dng khun lc S sang dng R (khng c v). Ph cu khng chu c nhit qu lnh v qua nng. Nhit gi chng thch hp l 18oC - 30oC. 1.5. Cu trc khng nguyn 1.5.1. Khng nguyn v: bn cht polysaccharide. Da vo khng nguyn v, ph cu c chia thnh 85 typ huyt thanh. V gi vai tr quan trng trong c lc ca vi khun. 1.5.2. Khng nguyn thn: bao gm carbohydrat C c hiu nhm v protein M c hiu typ tng t nh lin cu A. 2. Kh nng gy bnh Ph cu thng gp t hu vi t l kh cao. Lc ng h hp b thng tn, ph cu xm nhp vo c th gy bnh ng h hp, in hnh l vim thy phi, thng do typ 1, 2, 3 gy nn. Bnh xy ra l t, c th tr thnh dch c bit v ma ng. N cng thng gy vim ph qun, p xe phi, vim mng phi c m. Ph cu cn l mt tc nhn thng gy vim mng no m tr em. Ngoi ra ph cu cn gy cc nhim khun khc nh vim xoang, vim tai, vim hng, vim kt mc mt, vim mng ngoi tim, vim khp, nhim khun huyt. 3. Chn on vi sinh vt Nhum Gram, nu thy nhiu cu khun Gram dng hnh ngn nn xp tng i ng thi vi bch cu a nhn v i thc bo s b chn on vim do ph cu v c th bt u iu tr. ng thi nui cy chn on xc nh. nh danh vi khun da vo c im hnh th, khun lc v mt s th nghim phn bit vi lin cu tan mu nh neufeld dng tnh, optochin dng tnh. nh typ ph cu bng phn ng phnh v. 4. Phng bnh v iu tr 4.1. Phng bnh Hin nay vaccine polysaccharide v cha ph bin. Ch yu l phng bnh chung: lc sc khng ca c th gim nh b cm cn bi dng sc khe, tr em ngi gi yu d b ph vim cn mc m v ma ng, lc c s thay i t ngt nhit . 4.2. iu tr Cn iu tr sm. Ph cu nhy cm vi erythromycin, penicillin, ampicillin, chloramphenicol, bactrim.

IV. NO M CU (NEISSERIA MENINGITIDIS)1. c im sinh vt hc 1.1. Hnh th Cu khun Gram m hnh ht c ph 0,8 x 0,6 m, thng ng thnh i ring l hoc thnh m nh. Xem trc tip t bnh phm c th tm thy vi khun trong bch cu a nhn. Vi khun khng lng, nhiu chng c v. 1.2. Tnh cht nui cy

95

No m cu hiu kh tuyt i, ch mc cc mi trng giu cht dinh dng nh thch mu, thch chocolat, Thayer - Martin 370C kh trng 5 -10% CO2. Khun lc to thnh sau 24 gi, nh, trn, li, bng, m u, mu xm. 1.3. Tnh cht sinh ha Oxydase dng tnh, catalase dng tnh, glucose dng tnh khng sinh hi, maltose dng tnh, sacharose m tnh. 1.4. Cu trc khng nguyn No m cu c cc thnh phn khng nguyn sau 1.4.1. Khng nguyn v: bn cht polysaccharide, c tnh cht c hiu nhm. Da vo khng nguyn ny, no m cu c chia thnh nhiu nhm huyt thanh: A, B, C, 29-E, H, I, K, L,W-135, X, Y, Z. Khng nguyn polysaccharide ca no m cu c phng thch ra trong dch no ty trong thi k u ca bnh nn c th chn on sm bnh bng cch xc nh khng nguyn ny trong dch no ty. 1.4.2. Khng nguyn vch: bn cht protein, nm mng ngoi cng ca ca vch t bo vi khun, c tnh c hiu typ. No m cu nhm B c 12 typ. 1.5. Sc khng No m cu c sc khng km. Rt d cht, trong bnh phm nc no ty n ch sng khong 3-4 gi sau khi ra khi c th. D b cht bi nhit (600C trong 10 pht). 2. Kh nng gy bnh No m cu thng sng vng t hu m khng gy nn triu chng, trng thi ngi lnh mang trng c th ko di trong t ngy n nhiu thng. Trong nhng iu kin khng thun li cho c th nh mc khng m, cm lnh vi khun i vo mu s gy nn vim mng no m. Him hn, n c th gy nn nhim khun huyt ti cp rt nng, vi st cao, pht ban, t vong cao do xut huyt thng thn. Rt him khi nhim khun huyt do no m cu tr thnh mn tnh v ko di nh st khng r cn nguyn. 3. Chn on vi sinh vt - Nhum soi: bnh phm l mu, dch no ty. Nhum Gram v nhum xanh mtylen kho st bch cu v tm song cu Gram m, hnh ht c ph. - Phn lp nui cy vi khun: ng thi cy bnh phm ln thch mu hoc thanh chocolat, 370C bnh c 5-10% CO 2. Phn lp v nh danh da vo tnh cht hnh th, tnh cht khun lc v s ln men cc loi ng: glucose dng tnh khng sinh hi, maltose dng tnh, sacharose m tnh. - Tm khng nguyn polysaccharide trong nc no ty bng k thut in di min dch i lu vi khng huyt thanh mu th c th chn on trong giai on sm. 4. Phng bnh v iu tr 4.1. Phng bnh 4.1.1. Phng bnh khng c hiu: cho tr em mc m v ma lnh, pht hin ngi lnh mang trng, pht hin sm v cch ly bnh nhn. Nhng ngi tip xc vi bnh phi cho ung khng sinh phng, thng dng rifampicin. 4.1.2. Phng bnh c hiu: Hin nay vaccine hn hp bao gm khng nguyn polysaccaride t 4 nhm no m cu A, C, Y v W-135 t ra rt hiu qu trong phng bnh. 4.2. iu tr iu tr bng khng sinh thch hp sm v liu lng cao. Cc khng sinh thng dng l peniciline, chloramphenicol, cc cephalosporin... Cc sunfamit thm qua mng no tt nhng t l no m cu khng thuc ny cao nn khng c dng mt mnh iu tr no m cu.

V. LU CU (NEISSERIA GONORRHOEAE)1. c im sinh vt hc 1.1. Hnh th

96

Ging nh no m cu, lu cu l cu khun Gram m hnh ht c ph, kch thc 0,8 x 0,6 m, thng xp thnh i. Trong lu cp tnh, lu cu thng rt nhiu v nm trong bch cu a nhn. Trong lu mn tnh lu cu t hn thng nm ngoi t bo. 1.2. Tnh cht nui cy Nui cy kh khn v khi ra ngoi c th vi khun rt d cht, cn phi cy ngay vo mi trng. Lu cu ch mc mi trng giu cht dinh dng nh thch chocolat, thch Thayer-Martin. Vi khun pht trin tt trong iu kin hiu kh pH 7,2-7,6, nhit 35360C v kh trng c 5-10% CO2. Khun lc sau 48 gi nh, trn, dt, mu xm nht. 1.3. Tnh cht sinh ha Oxydase dng tnh, catalase dng tnh, glucose dng tnh khng sinh hi, maltose m tnh, sacharose m tnh. 1.4. Sc khng Lu cu c sc khng km, cht nhanh khi ra khi c th. Trong bnh phm, vi khun cht nhit phng trong 1-2 gi, nhit 58 0C trong1 gi. Dung dch nitrat bc 1% git cht lu cu trong vng 2 pht. 1.5. Cu trc khng nguyn Lu cu c nhiu khng nguyn c hiu nhm v typ. Trong thc t, cc khng nguyn khng gip ch g cho vic xc nh vi khun. 2. Kh nng gy bnh Lu cu ch tm thy ngi, khng tm trong thin nhin. Ngi mc bnh do ly truyn trc tip qua ng sinh dc, qua da, nim mc, gic mc. N gy vim niu o (bnh lu) c nam v n. N cn gy nhim khun nhng b phn khc nhau ca ng sinh dc: nam gy vim tin lit tuyn, vim mo tinh v n gy vim c t cung, vim t cung, vim vi trng. Ngoi ra, lu cu c th gy nhim khun cc c quan khc nh nhim khun huyt a n nhim khun khp, vim mng trong tim, vim kt mc. tr s sinh, c th xy ra vim kt mc do lu cu khi i qua ng sinh dc ca m b bnh, nu khng iu tr kp thi c th gy m la. 3. Chn on vi sinh vt 3.1. Chn on trc tip - nam, ly m niu o lc sng sm trc khi i tiu ln u tin trong ngy. - n, ly m l niu o, c t cung, cc l ca tuyn m o. 3.1.1. Nhum Gram - Chn on bnh lu cp tnh: soi knh hin vi tiu bn nhum Gram, nu c nhiu bch cu a nhn trung tnh v nhiu song cu Gram m ni bo th c th xc nh bnh nhn mc bnh lu. - Chn on bnh lu mn tnh: trn tiu bn nhum gram bnh phm, thng t thy lu cu v lu cu nm ngoi bch cu a nhn, c th c nhiu tp khun khc, cn nui cy xc nh vi khun. 3.1.2. Chn on bng k thut PCR 3.2. Nui cy: Trong c hai trng hp cp v mn, cn cy bnh phm vo mi trng thch hp, phn lp v nh danh vi khun nh vo tnh cht nui cy v sinh ho. 3.2. Chn on huyt thanh - Tm khng th khng lu bng khng th n dng gn hunh quang. - Tm IgM bng ELISA chn on lu ngoi ng sinh dc. 4. Phng bnh v iu tr 4.1. Phng bnh Lu cu khng to nn min dch bo v sau khi khi bnh. Ch yu pht hin bnh v iu tr trit , ci thin hon cnh x hi. i vi tr s sinh phng nga vim kt mc do lu cu, sau khi tr lt lng nh mt git nitrat bc 1%. 4.2. iu tr

97

Hin nay, xut hin nhng chng lu cu khng vi penicillin G, do cn phi lm khng sinh la chn khng sinh thch hp cho vic iu tr bnh. Tuy nhin trong thc t, penicillin G vn l khng sinh thng dng v nhiu trng hp cho kt qu tt. Ngoi ra khng sinh nh ampicillin, oxacillin, spectinomycin, cefoxitin, rifamycin cng dng iu tr tt bnh lu. Cn iu tr trit trnh chuyn sang lu mn tnh. i vi lu mn tnh, chn on kh v iu tr phc tp, tn km.

H VI KHUN NG RUT (Enterobacteriaceae)Mc tiu hc tp 1. Trnh by c i cng v h vi khun ng rut. 2. Trnh by c cc c im sinh vt hc v kh nng gy bnh ca cc vi khun E.coli, Salmonella, Shigella, Klebsiella v Proteus. 3. Nu c phng php chn on vi sinh vt, nguyn tc phng v iu tr bnh i vi E.coli, Salmonella, Shigella, Klebsiella v Proteus.

I. I CNG V H VI KHUN NG RUT1. Ni c tr Cc vi khun ng rut thng sng ng tiu ha ca ngi v ng vt, c th gy bnh hoc khng gy bnh. Ngoi ra chng c th sng ngoi cnh (t, nc) v trong thc n. 2. Hnh th Cc vi khun thuc h Enterobacteriaceae l nhng trc khun gram m khng sinh nha bo. Mt s ging vi khun thng khng di ng (Klebsiella, Shigella), mt s vi khun khc di ng nh c lng xung quanh thn t bo. Mt s ging c v nhn thy c nh knh hin vi thng nh Klebsiella. 3. Nui cy Cc vi khun ng rut hiu kh k kh ty tin, pht trin c trn cc mi trng nui cy thng thng. Trn cc mi trng c, cc khun lc ca cc vi khun ng rut thng nhn, bng (dng S). Tnh cht ny c th bin i sau nhiu ln nui cy lin tip thnh cc khun lc c b mt kh v x x (dng R). Cc khun lc ca cc vi khun c v nh Klebsiella l khun lc nhy, ln hn khun lc dng S v c xu hng ha ln vo nhau. Nghin cu cc tnh cht sinh vt ha hc gip cho vic nh loi vi khun. 4. Tnh cht sinh vt ha hc Cc vi khun thuc h Enterobacteriaceae ln men glucose, c sinh hi hoc khng sinh hi, oxidase m tnh, catalase dng tnh, kh nitrate thnh nitrite. Ln men hoc khng ln men mt s ng (v d lactose). C hay khng c mt s enzymeeee nh urease, tryptophanase. Kh nng sinh ra H2S khi d ha protein, axt amin hoc cc dn cht c lu hunh... 5. Cu trc khng nguyn cc vi khun ng rut ngi ta c th phn bit: Cc khng nguyn thn hoc khng nguyn O

98

Cc khng nguyn lng hoc khng nguyn H Cc khng nguyn b mt (v hoc mng bc) c gi l khng nguyn K. Vic nghin cu cc khng nguyn khc nhau ny cho php phn chia cc vi khun thuc cng mt loi hoc mt ging ra cc type huyt thanh. 5.1 Khng nguyn O L khng nguyn nm trong vch t bo vi khun, bn cht l lipopolysaccharide (LPS) bao gm: Thnh phn protein lm cho phc hp c tnh cht khng nguyn. Thnh phn polysaccharide quyt nh tnh c hiu ca khng nguyn. Thnh phn lipid A chu trch nhim v tnh c. Khng nguyn O (LPS) l ni c t, khi tim cho ng vt, n gy ra cc phn ng gim bch cu, st v nhim c. Cc phn ng ny u thy bnh nhn mc bnh thng hn v sc ni c t. C th ngi hoc ng vt p ng li vi khng nguyn O bng khng th O. Khng nguyn O khi gp khng th tng ng s xy ra phn ng ngng kt gi l hin tng ngng kt O: thn vi khun ngng kt vi nhau di dng nhng ht nh, lc kh tan. 5.2. Khng nguyn H L khng nguyn ca lng ch c nhng vi khun di ng v c bn cht l protein ging nh myosin ca c. Khng nguyn H kch thch c th hnh thnh khng th H v khi gp nhau s xy ra hin tng ngng kt H, trong cc vi khun ngng kt li vi nhau do cc lng kt dnh li to nn cc ht ngng kt rt d tan khi lc. Cc vi khun di ng khi cho tip xc vi cc khng th H tng ng th chng b bt ng. 5.3. Khng nguyn b mt L khng nguyn bao quanh thn ca vi khun hoc di dng mt ci v nhn thy c r rng knh hin vi thng (v d khng nguyn K ca Klebsiella) hoc l di dng mt mng bc khng nhn thy c knh hin vi thng (v d khng nguyn Vi ca Salmonella typhi) 6. Phn loi C nhiu cch phn loi h Enterobacteriaceae. Theo cch phn loi ca Bergeys Manual (1984) chia Enterobacteriaceae lm 13 ging chnh nh sau: Cc ging : I. Escherichia II. Shigella III. Edwardsiella IV. Citrobacter V. Salmonella VI. Klebsiella VII. Enterobacter VIII. Serratia IX. Proteus X. Providencia XI. Morganella XII. Yersinia XIII. Erwinia Trong cc ging k trn th cc ging vi khun c ngha y hc nht l : Escherichia; Shigella; Salmonella; Klebsiella; Enterobacter; Proteus; Yersinia; cn cc ging khc t ngha

II. ESCHERICHIA COLIEscherichia coli (E.coli) l nhng vi khun k sinh, bnh thng c rut, nhng ng thi cng l tc nhn gy bnh khi chng xm nhp vo cc c quan khc nh ng

99

niu, ng mu..., v c mt s chng E. coli c kh nng gy bnh a chy nh ETEC, EPEC, EIEC... 1. c im sinh vt hc 1.1. Hnh th E.coli l trc khun gram m, di ng do c lng quanh thn, mt s chng E.coli c v polysaccharide, khng sinh nha bo. 1.2. Tnh cht nui cy E.coli l vi khun hiu kh hoc k kh khng bt buc, pht trin d dng trn cc mi trng nui cy thng thng, mt s c th pht trin c mi trng tng hp n gin. Nhit thch hp 370C, pH thch hp l 7 - 7,2. 1.3. Tnh cht sinh vt ha hc E.coli ln men nhiu loi ng sinh axit v sinh hi nh: Glucose, lactose, ramnose; indol dng tnh, methyl dng tnh, VP m tnh, citrat m tnh, urease m tnh, H 2S m tnh. 1.4. Khng nguyn ca E.coli E.coli c rt nhiu type huyt thanh m cng thc da vo s xc nh khng nguyn thn O, khng nguyn v K v khng nguyn lng H. Khng nguyn O : C khong 150 yu t khc nhau v mt huyt thanh. Khng nguyn K : c chia ra thnh loi L, A hoc B ty theo sc khng i vi nhit. C chng 100 khng nguyn K khc nhau. Khng nguyn H : xc nh c khong 50 yu t H. 2. Kh nng gy bnh cho ngi E.coli l thnh phn vi khun hiu kh ch yu rut ca ngi bnh thng. S c mt ca E.coli ngoi cnh v trong thc n chng t c s nhim bn do phn. Tuy th vai tr gy bnh ca n c ni ti t lu. E.coli c th gy nhim khun nhiu c quan trong c th ngi. 2.1. Bnh tiu chy do E.coli Cc E.coli gy bnh tiu chy ngi gm c: 2.1.1. Enterotoxigenic E.coli (ETEC) L loi E.coli sinh c t rut. ETEC l mt nguyn nhn quan trng gy tiu chy nng ging triu chng do Vibrio cholerae 01 gy ra ngi. Bnh tiu chy do ETEC xy ra ch yu cc x nhit i v c th gp cc la tui khc nhau, nhng c bit tr nh thng thy bnh cnh lm sng nng d dn ti tnh trng kit nc v ri lon in gii. ETEC cn l mt nguyn nhn thng gy tiu chy cho khch du lch t cc nc pht trin sang cc nc ang pht trin. C ch gy bnh: ETEC vo rut s gn vo nim mc rut nh cc yu t bm dnh, ng thi sn sinh ra c t rut tc ng ln t bo nim mc rut gy xut tit ra mt s lng ln mt cht dch ng trng vi huyt tng. Bnh nhn nn, tiu chy lin tc, phn ln c au nhc bp c, au bng v st nh. C hai loi c t rut c nghin cu k v tnh cht sinh l, sinh ha v tnh truyn bng plasmid l : c t rut LT (Heat - labile) c t rut ST (Heat - stable) Nhng chng ETEC c th sinh ra mt hoc hai loi c t rut ty thuc vo plasmid m chng mang.

100

LT loi c t rut b hy bi nhit, l mt protein gm 2 tiu phn A (Active) v B (Binding) c chc nng ring bit. Tiu phn A c hai tiu n v A 1 v A2, tiu phn B c 5 tiu n v B1, B2, B3, B4 v B5. Cc tiu n v B c chc nng gn vi th th ganglioside GM1 b mt t bo biu m rut v chun b m ng cho tiu phn A m ch yu l A 1 xm nhp vo bn trong t bo. Tiu n v A tc ng ti v tr ch mt trong mng bo tng ni iu ha enzymee adenylate cyclase. Adenylate cyclase b hot ha v lm tng hm lng adenosine monophosphate vng (AMP vng). Hin tng ny dn ti s tng thm ca cc in gii v nc qua mng rut, gy tiu chy cp v kit nc, ri lon in gii. ST, loi c t rut khng nhit, l mt phn t c trng lng thp nht v khng c tnh khng nguyn. Th th dnh cho ST khc vi th th LT. Sau khi gn vi th th, ST s hot ha guanylate cyclase trong t bo nim mc rut. Hin tng ny dn ti s tng guanosine monophosphate vng (GMP vng) v do xy ra tnh trng tng tit dch rut. 2.1.2. Enteropathogenic E.coli (EPEC) EPEC hin nay c bit gm mt s type huyt thanh thng gy bnh tiu chy cp (bnh vim d dy - rut) tr em la tui nh (tr di mt tui), c th gy thnh dch. Cc v dch do EPEC thng hay gp trong bnh vin, c ch gy bnh ca EPEC cha c bit r. Cc EPEC phn lp t cc v dch thng l thuc cc typee huyt thanh: O26 : B6 O111 : B4 O126 : B16 O55 : B5 O119 : B4 O127 : B18 O86 : B7 O125 : B15 O128 : B12 2.1.3. Enteroinvasive E.coli (EIEC) L loi E.coli gy bnh bng c ch xm nhp t bo biu m nim mc rut, gy tiu chy ngi ln v tr em vi nhng triu chng bnh l ging Shigella: ngha l au bng qun, mt rn, i tiu nhiu ln, phn c nhiu mi nhy v mu. Ngi ta chng minh c rng kh nng xm nhp t chc rut ca EIEC c chi phi bi plasmid. EIEC c th khng ln men lactose, khng di ng v ging Shigella v nhiu mt k c cu trc khng nguyn. Do vy nhng v dch tiu chy do EIEC gy nn d b ln ln vi tiu chy do Shigella. 2.1.4. Enteroadherent E.coli (EAEC) L loi E.coli bm dnh ng rut gy bnh do bm vo nim mc v lm tn thng chc nng rut. 2.1.5. Enterohemorrhagic E.coli (EHEC) EHEC l mt trong nhng tc nhn gy tiu chy c th dn ti vim i trng xut huyt v hi chng tan mu - ure huyt. EHEC l nhng chng E.coli c kh nng sn xut mt c t gy c t bo Vero (Verocytotoxin), gi l VT. 2.2. Cc nhim khun khc do E.coli E.coli c th gy nn nhim khun ng tit niu: s ng nc tiu do si, thai nghn... to iu kin thun li cho bnh nhim khun ng tit niu d xy ra . Mt khc, khi thng niu o, ngi ta c th gy ra nhim khun ngc dng. E.coli c th gy ra nhim khun ng sinh dc, nhim khun gan mt, vim mng no tr cn b, nhim khun huyt ... 3. Chn on vi sinh vt Ch yu l chn on trc tip phn lp vi khun t bnh phm. Trong bnh tiu chy do E.coli th cy phn phn lp vi khun. Gia cc nhm E.coli khng th phn bit c bng cc th nghim sinh vt ha hc. i vi EPEC th xc

101

nh type huyt thanh bng cc khng huyt thanh mu. i vi ETEC thng c xc nh bng cc th nghim tm kh nng sinh c t rut thng thng nht l tm c t rut bng th nghim ELISA. i vi EIEC cn xc nh tnh xm nhp, c th dng th nghim Sereny xc nh. i vi EHEC tm kh nng sinh verocytotoxin. Trong nhim khun ng tit niu th ly nc tiu gia dng ca bnh nhn nui cy. Ch nui cy khi nhum soi knh hin vi cn nc tiu thy nhiu bch cu a nhn cng vi vi khun. Cn phi nh lng vi khun trong 1 ml nc tiu c th khng nh vai tr gy bnh ca vi khun phn lp c nc tiu. 4. Phng bnh v cha bnh Hin nay cha c vaccine c hiu. Ch yu l phng bnh chung m ch yu l tn trng cc ni quy v v sinh. Qua nhiu cng trnh nghin cu cho thy mt s ln cc chng E.coli gy bnh khng cc khng sinh v hin tng mt chng vi khun E.coli khng vi nhiu loi khng sinh cng kh ph bin. Do vy nn da vo kt qu ca khng sinh la chn khng sinh thch hp trong cha bnh.

III. SHIGELLAShigella l tc nhn gy ra bnh l trc khun ngi. 1. c im sinh vt hc Shigella l trc khun Gram m tnh, khng c lng, v vy khng c kh nng di ng, khng c v khng sinh nh bo. Shigella ln men glucose khng sinh hi, ln men manitol (tr Shigella dysenteriae khng ln men manitol), hu ht Shigella khng ln men lactose, ch c Shigella sonnei ln men lactose nhng chm. Khng sinh H2S, Urease m tnh phn ng Indol thay i, phn ng metyl dng tnh, phn ng VP m tnh, phn ng citrat m tnh Shigella c khng nguyn thn O, khng c khng nguyn H. Cn c vo khng nguyn O v tnh cht sinh ha, ngi ta chia Shigella ra lm 4 nhm: 1.1. Nhm A (Shigella dysenteriae) Khng ln men manitol, c 10 type huyt thanh c k hiu bng cc ch s Rp t 1 - 10. Cc type huyt thanh trong nhm khng c quan h v khng nguyn vi nhau v cng khng c quan h khng nguyn vi cc nhm khc. Type 1 (Sh. dysenteriae 1) hay cn gi l trc khun Shiga l type c ngoi c t. 1.2. Nhm B (Shigella flexneri) Ln men manitol, c 6 type huyt thanh. Cc type ny c 1 khng nguyn nhm chung v mi mt type huyt thanh li c 1 khng nguyn c hiu type. 1.3. Nhm C (Shigella boydii) Ln men manitol, c 15 type huyt thanh, mi type c khng nguyn c hiu type. 1.4. Nhm D (Shigella sonnei) Ln men manitol, ln men lactose chm, ch c 1 type huyt thanh. 2. Kh nng gy bnh cho ngi Shigella gy bnh l trc khun ngi, y l mt bnh truyn nhim c th gy thnh cc v dch a phng. Thng tn c hiu khu tr rut gi, trn lm sng biu hin bng hi chng l vi cc triu chng: au bng qun, i ngoi nhiu ln, phn c nhiu mi nhy v thng c mu. Shigella gy bnh bng c ch xm nhp vo t bo biu m ca nim mc rut v nhn ln vi s lng ln trong t chc rut.

102

Cc Shigella u c ni c t. Ring trc khun Shiga cn c thm ngoi c t bn cht l protein . Ni c t Shigella cu to nh khng nguyn thn, c c tnh mnh nhng tnh khng nguyn yu. Tc dng chnh ca ni c t l gy phn ng ti rut. Ngoi c t ca trc khun Shiga khng ging nh c t rut ca Vibrio cholerae 01 v ETEC, hot tnh sinh hc ch yu ca ngoi c t trc khun Shiga l tc dng c i vi t bo. Vit Nam, Shigella gy bnh l trc khun thng gp nht l nhm B (Shigella flexneri) v nhm A (Shigella dysenteriae). Dch t hc: Bnh ly theo ng tiu ha, do n ung phi cc thc n, nc ung b nhim khun. Rui l vt ch trung gian truyn bnh. Ngi lnh mang vi khun v ngi bnh ng vai tr quan trng gy dch. Dch thng xy ra vo ma h. Min dch: Ngi ta cho rng khng th dch th khng c hiu lc v thng tn ca bnh trn b mt ca ng tiu ha. Ngc li cc min dch ti ch rut c th c mt vai tr quan trng trc ht l cc IgA tit c trong ng rut v cc i thc bo c hot ha. 3. Chn on vi sinh vt Cy phn l phng php chn on tt nht. Bnh phm cn c ly sm trc khi s dng khng sinh, ly ch phn c biu hin bnh l (c mu c nhy) v phi chuyn n phng xt nghim vi trng nhanh chng. Nui cy phn lp vi khun trn cc mi trng thch hp: mi trng khng c cht c ch (thch lactose) v mi trng c cht c ch (DCA, SS hoc Istrati). Xc nh vi khun da vo cc tnh cht sinh vt ha hc v lm phn ng ngng kt vi khng huyt thanh mu ca Shigella. Trong bnh l trc khun, cy mu khng tm c vi khun. 4. Phng bnh v cha bnh 4.1.Phng bnh Ch yu l cch ly bnh nhn, kh trng phn v nc thi, pht hin v iu tr ngi lnh mang vi khun, p dng cc bin php v sinh v kim tra dch t i vi ngun nc, thc n... Hin nay vn cha c vaccine phng bnh c hiu lc nh mong mun... ang th nghim dng vaccine sng gim c lc ng ung nhm to nn min dch ti ch rut. Vaccine sng ny ch c kh nng bo v c hiu i vi type. 4.2.Cha bnh Dng khng sinh tiu dit vi khun, vic chn khng sinh thch hp da vo kt qu khng sinh . Vic s dng khng sinh ba bi, thiu thn trng s c nguy c lm tng nhanh cc chng c sc khng i vi khng sinh v tng nguy c b lon khun vi tt c cc hu qu nghim trng ca n.

IV. SALMONELLAHin nay c ti 2000 type huyt thanh Salmonella khc nhau. Chng gy bnh cho ngi hoc ng vt hoc c hai. Cc bnh do Salmonella gy ra ngi c th chia thnh 2 nhm: thng hn v khng phi thng hn. 1. c im sinh vt hc 1.1. Hnh th Salmonella l trc khun gram m. Hu ht cc Salmonella u c lng xung quanh thn (Tr Salmonella gallinarum v Salmonella pullorum), v vy c kh nng di ng, khng sinh nha bo.

103

1.2. Tnh cht sinh vt ha hc Salmonella ln men glucose c sinh hi (tr Salmonella typhi ln men glucose khng sinh hi) khng ln men lactose, indol m tnh, methyl dng tnh, VP m tnh, citrat thay i, urease m tnh, H2S dng tnh (tr Salmonella paratyphi A: H2S m tnh)... 1.3. Cu trc khng nguyn 1.3.1. Khng nguyn O Mi Salmonella c th c mt hoc nhiu yu t khng nguyn. Hin nay ngi ta bit c 67 yu t khng nguyn O. Vic xc nh cc yu t khng nguyn O l ht sc quan trng nh nhm v nh type. 1.3.2. Khng nguyn H Ch c nhng Salmonella c lng. Khng nguyn H ca Salmonella c th tn ti di 2 pha: pha 1 c ghi bng ch vit thng a, b, c, d... v pha 2 c ghi bng cc ch s rp 1, 2,,, 1.3.3. Khng nguyn Vi L khng nguyn b mt bao bn ngoi vch t bo vi khun, di dng mt mng mng khng nhn thy c knh hin vi thng. Khng nguyn Vi ch c 2 type huyt thanh Salmonella typhi v S. paratyphi C. Ngi ta da vo s khc nhau v cu trc khng nguyn xp loi Salmonella. Mt s type huyt thanh Salmonella ch yu gy bnh cho ngi bao gm : Salmonella typhi : Ch gy bnh cho ngi. nc ta bnh thng hn ch yu do S. typhi gy ra. Salmonella paratyphi A : Ch gy bnh thng hn cho ngi v cng hay gp nc ta sau S.typhi. Salmonella paratyphi B : Gy bnh thng hn ch yu cho ngi, i khi c sc vt. Bnh thng gp cc nc chu u. Salmonella paratyphi C : Gy bnh thng hn, vim d dy rut v nhim khun huyt. Bnh thng gp cc nc ng Nam . Salmonella typhimurium v Salmonella enteritidis : Gy bnh cho ngi v gia sc, gp trn ton th gii. Chng l nguyn nhn gy nhim trng, nhim c thc n do n phi thc n nhim Salmonella. Salmonella cholerae suis : Loi ny hay gy nhim khun huyt. 2. Kh nng gy bnh cho ngi 2.1. Bnh thng hn nc ta, bnh thng hn ch yu do S. typhi, sau n S. paratyphi A, cn S. paratyphi B v S. paratyphi C th t gp. Bnh ly t ngi ny sang ngi khc, qua thc n, nc ung b nhim khun. Sau khi khi bnh v mt lm sng, khong 5% bnh nhn tr thnh ngi lnh mang vi khun ko di hng thng hoc hng nm. h, cha Salmonella l ng mt v vi khun vn c tip tc o thi theo phn ra ngoi cnh. Ngi lnh mang vi khun l ngun lan truyn bnh quan trng. Sinh bnh hc: Trc khun thng hn vo c th qua ng tiu ha n rut non th chui qua nim mc rut ri vo cc hch mc treo rut. chng nhn ln v mt phn vi khun b dung gii, gii phng ra ni c t. Ni c t kch thch thn kinh giao cm bng, gy thng tn mng Peyer, xut huyt tiu ha, c th gy thng rut. Ngoi ra, ni c t theo mu ln kch thch trung tm thn kinh thc vt no tht ba, gy ra trng thi st ko di, li b, v gy ra bin chng try tim mch... T cc hch mc treo rut vi khun lan trn

104

vo mu gy nn nhim khun huyt v lan i khp c th, ri vi khun vo mt v t quay tr li rut. Vi khun theo phn ra ngoi cnh. 2.2. Cc bnh khc Cc bnh khng phi thng hn do Salmonella gy ra thng l mt nhim trng gii hn ng tiu ha trong cc trng hp nhim trng nhim c thc n m Salmonella typhimurium... l tc nhn hay gp nht, sau l Salmonella enteritidis... Nhim trng nhim c do Salmonella c thi gian nung bnh t 10 n 48 gi. Bnh biu hin c st, nn, tiu chy. Bnh khi sau 2 - 5 ngy, khng c bin chng. Ngoi ra, Salmonella c th gy nn cc tn thng ngoi ng tiu ha nh vim mng no, th nhim trng huyt n thun, nhim trng phi... 3. Chn on vi sinh vt 3.1. Chn on trc tip Phn lp vi khun t cc bnh phm nh mu (cy mu), phn (cy phn) v cc bnh phm khc . 3.1.1.Cy mu Ly 5ml n 10ml mu tnh mch bnh nhn lc st cao cy vo bnh canh thang c mt b, m 370C, sau 24 n 48 gi nu vi khun mc, cn phi kim tra hnh th, tnh cht bt mu khi nhum Gram, kim tra tnh cht sinh vt ha hc, xc nh cng thc khng nguyn vi cc khng huyt thanh Salmonella mu. i vi bnh thng hn, nu bnh nhn cha s dng khng sinh th gi tr ca phng php cy mu cao. Nu cy mu vo : Tun l u ca bnh th t l dng tnh t 90% Tun l th hai ca bnh, dng tnh t 70% - 80% Tun l th ba, t l dng tnh t 40 - 60% Nu bnh ti pht, cy mu s tm thy vi khun thng xuyn trong nhiu ngy. 3.1.2. Cy phn Thng dng tnh t tun th 2 tr i. Nui cy phn lp vi khun mi trng tng sinh v mi trng c cht c ch (mi trng SS, DCA, Istrati, Endo...). Xc nh vi khun da vo tnh cht sinh vt ha hc v lm phn ng ngng kt vi khng huyt thanh mu. Khi nghi ng mt trng hp mc bnh thng hn phi ng thi xt nghim cy mu, cy phn v lm huyt thanh chn on. Cy phn l bin php duy nht chn on vi sinh vt trong trng hp ng c thc n nghi do Salmonella v trong vic xc nh ngi lnh mang mm bnh. 3.1.3. Cy cc bnh phm khc Vi khun thng hn cn c th phn lp bng cch cy ty xng, nc tiu, dch o ban, dch mt ca bnh nhn. 3.2. Chn on huyt thanh Sau khi nhim Salmonella t 7 n 10 ngy, trong mu bnh nhn xut hin khng th O ca Salmonella, sau ngy th 12 n ngy th 14 xut hin khng th H. Khng th O, tn ti trong mu trung bnh 3 thng, khng th H tn ti 1 n 2 nm. Ly huyt thanh cc bnh nhn tm khng th ngng kt ca Salmonella bng phn ng ngng kt Widal. Trong bnh thng hn, chn on huyt thanh (Widal) t tun l th hai, lm 2 ln cch nhau mt tun l tm ng lc khng th.

105

4. Phng bnh v cha bnh 4.1. Phng bnh Thc hin cc bin php v sinh v phn, nc, rc, tch cc dit rui. Phi n chn, ung si, ra tay trc khi n... Qun l cht ch bnh nhn. Pht hin ngi lnh mang mm bnh iu tr trit . Tim vaccine T.A.B l loi vaccine cht. Mt s nc dng vaccine thng hn sng gim c lc v vaccine chit t khng nguyn Vi ca Salmonella. 4.2. Cha bnh Dit vi khun Salmonella bng khng sinh. Nhng thuc khng sinh thng dng l chloramphenicol, ampicillin vi liu lng thch hp trnh bin chng tru tim mch v thuc dit vi khun lm gii phng ra qu nhiu ni c t. Tuy nhin ngy nay cng xut hin nhng chng Salmonella khng vi cc khng sinh trn, v vy cn lm khng sinh chn khng sinh thch hp.

V. KLEBSIELLA PNEUMONIAELoi Klebsiella c nhiu type c kh nng gy bnh cho ngi nh: - Klebsiella pneumoniae: Thng gy ra cc bi nhim ng h hp. - Klebsiella rhinoscleromatis : Gy bnh x cng mi. - Klebsiella ozenae: Gy bnh tr mi Klebsiella pneumoniae hay cn gi l ph trc khun Friedlander l loi vi khun rt ph bin trong thin nhin (nc, t), n k sinh ng h hp trn ca ngi, l tc nhn gy bnh c hi. 1. c im sinh vt hc 1.1. Hnh th Trong bnh phm K. pneumoniae c hnh trc khun ngn, gram m, bt mu m hai cc, vi khun ny c nhiu hnh th, c khi nh cu khun, c khi li hnh di, c v, khng di ng, khng sinh nha bo. 1.2. Tnh cht nui cy Vi khun d mc trn mi trng nui cy thng thng. Trn thch dinh dng hay thch mu, khun lc ly nhy, mu xm. Trong canh thang, vi khun mc nhanh v c u, ay ng c lng cn. 1.3. Tnh cht sinh vt ha hc Ln men nhiu loi ng sinh acid v hi nh : Glucose, lactose, manit. Phn ng indol m tnh, phn ng metyl m tnh, phn ng VP dng tnh, phn ng citrat dng tnh, urease dng tnh, H2S m tnh. 1.4. Cu trc khng nguyn Khng nguyn thn O : C 5 type Khng nguyn v K : Bn cht l polysaccharide, mang tnh cht c hiu type, c 72 type, trong type 1 v type 2 hay gp nht trong nhim khun ng h hp. 2. Kh nng gy bnh cho ngi Klebsiella pneumoniae l loi vi khun gy bnh c iu kin gi l gy bnh c hi. Nhng nhim trng c hi xy ra ch yu mi trng bnh vin v trn nhng bnh nhn b suy kit, suy gim min dch. Nhng iu kin cc nhim trng c hi xut hin l :

106

- Ngy cng c nhiu loi khng sinh ph rng, vic s dng khng sinh rng ri v thiu thn trng lm mt th qun bnh ca vi khun ch bnh thng, ng thi lm cho vi khun c chn lc bi khng sinh v to nn sc khng i vi khng sinh. - Cc th thut nh ni soi, thng tim... c pht trin v p dng ngy cng nhiu trong cc bnh vin. Khi p dng cc th thut ny c th a vi khun vo c th qua ng thng... - Nhng bnh nhn m sc khng gim st nghim trng do mc cc bnh lm suy gim min dch (v d: K mu, suy ty...) Klebsiella pneumoniae c th gy ra : Nhim trng ng h hp di nh vim phi, vim ph qun phi th pht sau cm, sau si, sau ho g hoc cc bnh nhn ang hi sc h hp (ang dng my h hp nhn to). Nhim trng mu : Thng gp nhng bnh nhn b suy kit nh x gan, ung th mu, suy ty... Ngoi ra cn c th gy nhim trng ng tit niu, ng mt hoc ng sinh dc, vim mng no, vim tai, vim xoang v vim ni tm mc. 3. Chn on vi sinh vt Ch yu da vo chn on trc tip, phn lp vi khun t cc bnh phm m, mu v.v... ty theo th bnh. Nui cy ln cc mi trng thch hp phn lp v xc nh vi khun da vo hnh th, tnh cht nui cy c bit (khun lc nhy, dnh), tnh cht sinh vt ha hc, kh nng gy bnh thc nghim. Xc nh type bng phn ng ngng kt hoc phn ng phnh v vi khng huyt thanh c hiu type. 4. Phng bnh v cha bnh 4.1. Phng bnh Cha c vaccine phng bnh c hiu. Ch yu l trnh nhng iu kin thun li cho nhim trng c hi xut hin bng cch nng cao sc khng ca ngi bnh v d phng tt cc nhim trng bnh vin. 4.2. Cha bnh Da vo kt qu ca khng sinh chn khng sinh cng hiu. Klebsiella pneumoniae thng c sc khng cao vi khng sinh.

VI. PROTEUSGing Proteus k sinh rut v cc hc t nhin ca ngi (v d : ng tai ngoi). Chng l loi vi khun gy bnh c hi 1. c im sinh vt hc 1.1. Hnh th Trc khun gram m, rt di ng. Vi khun c nhiu hnh th thay i trn cc mi trng khc nhau, t dng trc khun n dng hnh si di. 1.2. Tnh cht nui cy Vi khun mc d dng trn cc mi trng nui cy thng thng. Trn mi trng thch dinh dng, khun lc c mt trung tm lan dn ra, tng t, tng t , mi t l mt gn sng v c mi thi c bit. Trn mi trng c natri deoxycholate: Proteus mc thnh khun lc trn, ring bit khng gn sng, c mt im en trung tm, xung quanh mu trng nht. 1.3. Tnh cht sinh vt ha hc

107

Khng ln men lactose. a s Proteus : H2S dng tnh v urease dng tnh. Da vo tnh cht sinh vt ha hc ngi ta phn loi ging Proteus thnh cc loi: Proteus mirabilis, Proteus vulgaris, Proteus myxofaciens, Proteus penneri. 1.4. Cu trc khng nguyn Cu trc khng nguyn ca Proteus rt phc tp v khng c vn dng vo cng tc thc t hng ngy. Ngi ta thy c mt mi tng quan c bit gia khng nguyn O ca mt s chng Proteus (c gi l OX2 ; OX19; OXK) v Rickettsia. V vy, ngi ta dng cc chng ny lm khng nguyn trong chn on huyt thanh bnh do Rickettsia (phn ng Weil - Felix).

108

2. Kh nng gy bnh Proteus l mt loi vi khun "gy bnh c hi". Chng c th gy ra : Vim tai gia c m - Vim mng no th pht sau vim ti gia tr cn b. - Nhim khun ng tit niu - Nhim khun huyt ... 3. Chn on vi sinh vt Phn lp vi khun t cc bnh phm nh : m tai, nc tiu, mu ... ty theo th bnh lm sng. c im ca cc tn thng v m do Proteus gy ra c mi thi nh trong hoi th do vi khun k kh gy nn. Nui cy trn cc mi trng thng thng. Xc nh vi khun da vo hnh thi khun lc gn sng, mi thi c bit trn da mi trng v trc khun Gram m urease dng tnh v mt s tnh cht sinh vt ha hc khc. Mun phn lp thnh khun lc ring r th nui cy trn mi trng c Natri desoxycholat, Proteus s mc thnh khun lc ring bit c chm en gia sau 48 gi. 4. Phng bnh v cha bnh 4.1. Phng bnh Nng cao th trng ngi bnh, khi p dng cc th thut thm khm phi tuyt i v trng d phng tt cc nhim trng bnh vin... 4.2. Cha bnh S dng khng sinh da vo kt qu ca khng sinh . Vi khun ny thng c sc khng cao vi khng sinh.

109

VI KHUN DCH HCH V LEGIONELLA PNEUMOPHILAMc tiu hc tp 1. Trnh by c c tnh sinh vt hc ca vi khun dch hch v Legionella pneumophila 2. Trnh by c kh nng gy bnh ca hai vi khun ny 3. Trnh by c phng php chn on sinh vt hc, phng php phng nga v iu tr

I. VI KHUN DCH HCH (Yersinia pestis)Yersinia pestis thuc ging Yersinia, thuc h vi khun ng rut (Enterobacteriaceae) Trc khun dch hch c A. Yersin phn lp nm 1894 trong mt v dch hch Hng Kng. Nm 1896, Lehmann v Neumann t tn cho vi khun ny l Bacterium pestis. Nm 1944, Van Loghen chuyn chng sang ging Yersinia ghi cng ca A. Yersin. Vi khun dch hch gy nn bnh dch hch l bnh ca mt s loi ng vt (ch yu l cc loi chut), ly sang ngi qua b cht, c bnh thin nhin, d pht thnh dch ln. Dch hch l bnh ti nguy him, c xp vo nhm 4 bnh thuc din phi khai bo bt buc: dch hch, dch t, u ma v st vng. nc ta, bnh dch hch c pht hin ln u tin nm 1898 Nha trang, sau bnh pht trin mnh min Nam. Hin nay vn cn mt s dch hch ch yu vng Ty nguyn. 1. c im sinh vt hc 1.1. Hnh thi v tnh cht bt mu Vi khun dch hch l trc khun ngn, hnh bu dc nh, kch thc 0,5 -0,8 x 1-2 m, Gram m, bt mu m hai u, nht l khi nhum Wayson hay xanh methylen. Trong bnh phm vi khun ng ring l hoc xp i v c v. Trong mi trng nui cy 37oC th c v, nu nui cy 28oC th khng c v. Khng sinh nha bo, khng di ng. 1.2. Tnh cht nui cy Trc khun dch hch d mc trn cc mi trng nui cy thng thng, nhng chm. Hiu k kh tu tin, nhit thch hp l 28oC. - Trn canh thang Yersinia pestis lc u lm c u nh, dn dn sau 24 - 48 gi vi khun pht trin to mt vng mng trn b mt v lng cn di y, canh thang tr nn tng i trong. - Trn thch thng: vi khun mc chm to khun lc rt nh (0,1mm) sau 24 gi. Sau 48 - 72 gi 280C, ng knh mi t c 1- 1,5 mm, b tri mng ra, khng u, trung tm li, hi trong, mu xm nht. 1.3. Tnh cht sinh vt ha hc Vi khun dch hch khng di ng. Oxydase m tnh, catalase dng tnh. Ln men ng glucose khng sinh hi, manitol dng tnh, ONPG dng tnh, c enzyme Dnase, kh nitrat thnh nitrit. Citrat simmon thay i tu theo chng, lactose m tnh, rhamnose m tnh, saccharose m tnh. Indol m tnh, Voges Proskauer m tnh, khng to enzyme urease, khng sinh H2S, ornithin decarboxylase (ODC) m tnh, lysin decarboxylase (LDC) m tnh, arginin dihydrolase (ADH) m tnh. Vi khun dch hch b ly gii bi phage c hiu. 1.4. Sc khng

110

Vi khun b tiu dit 550C/30 pht hoc 1000C/1 pht. Trong iu kin kh hanh hoc phi nng vi gi vi khun c th cht. Trong cc t chc, trong xc chut, t m, trong nc vi khun c th tn ti t vi chc ngy n vi thng. 1.5. Khng nguyn v cc yu t gy bnh - Khng nguyn v: Cn gi l khng nguyn F1 (Fraction 1), c trong iu kin nui cy vi khun 37oC hoc trong bnh phm ca c th ang b bnh. Bn cht l protein. Khng nguyn v gip cho vi khun chng li hin tng thc bo. - Khng nguyn V v W: L mt phc hp gm protein V v lipoprotein W. Cc khng nguyn ny lin quan n kh nng chng li hin tng thc bo. - Khng nguyn thn: l khng nguyn chung vi cc vi khun h ng rut. - c t: vi khun dch hch c 2 loi c t : + Ni c t: bn cht l Lipopolysaccharide gn lin vi vch t bo vi khun, gy ra cc triu chng st trong bnh dch hch. + c t chut (murine toxin) bn cht l protein nh mt ngoi c t, c tc ng lm tan hng cu, c hot tnh trn h thng mch mu gy ra mu v gy sc. 2. Kh nng gy bnh 2.1. Dch t hc Bnh dch hch l bnh ca loi gm nhm hoang di, trong loi chut Rattus vi 2 chng: chut ng v chut nh c vai tr quan trng nht. Ngi ch l vt ch ngu nhin mc phi do b b cht nhim khun t. - cha: Cc loi gm nhm hoang di - Cn trng mi gii: Ch yu l cc loi b cht Xenopsylla cheopis, ngoi ra c th gp Xenopsylla astia v cc cn trng ht mu nh Pulex irritans ... - i tng cm th: ng vt gm nhm hoang di v c th ly sang ngi. ng truyn bnh: u tin dch xy ra cc loi gm nhm hoang di ri truyn n chut ng, chut nh, sau truyn sang ngi l con ng hay gp nht hoc ngi ti bnh hoang di cng c th b b cht nhim khun t v mc bnh. Bnh dch hch c th truyn t ngi bnh sang ngi lnh do chy rn hoc c th truyn bnh trc tip t ngi sang ngi nu ngi mc bnh dch hch th phi. cha (gm nhm hoang di) - Xennopsylla cheopis - Xenopsylla astia Cn trng mi gii - Pulex irritans - Rui ht mu Chut - Chut ng - Chut nh

Cn trng mi gii NgiTh phi

Ngi

Chy, rn Hnh 1: S dy chuyn dch t

111

2.2. Gy bnh cho ngi Vi khun dch hch sau khi vo c th s vo h thng bch huyt v nhn ln trong hch, sau vo mu, ri c tr gan, lch, thn v cc hch su. Thi gian bnh t 3- 6 ngy, i khi ngn hn, ty thuc vo sc khng ca c th v c lc ca vi khun. Bnh dch hch c 3 th lm sng: - Th hch: Sau khi b b cht nhim khun t, ti ni t ni mn nc, i khi en gia. Vi khun xm nhp vo hch bch huyt gn vt t nht lm cho hch sng to, rn, dnh cht khng di ng v rt au. Bnh nhn st cao, mt v chng mt, triu chng nhim c nng. Nu khng c iu tr kp thi, bnh nhn s t vong vo ngy th 5 hoc th 6 ca bnh v nhim khun huyt. Th hch l th lm sng thng gp nht. - Th phi: C th nguyn pht do ly trc tip qua th phi ca ngi bnh hoc l th pht sau th hch. Bnh khi pht t ngt, st cao, ho, au lng ngc, m c mu. Bnh tin trin nhanh v rt nng, t vong sau 2 - 3 ngy nu khng c iu tr kp thi. Th phi rt d ly lan. - Th nhim khun huyt: C th l tin pht, nhng thng do bin chng ca th hch v th phi nguyn pht, gy thng tn c m da, mn xut huyt v huyt niu, st cao, cy mu dng tnh. T vong sau 2 - 3 ngy. 3. Chn on vi sinh vt 3.1. Chn on trc tip : Bnh phm l dch chc hch trong th hch, mu trong th nhim khun huyt, m trong th phi. T bnh phm lm tiu bn nhum gram (i vi th hch) hoc xanh methylen hoc Wayson. Phng php nhum trc tip c gi tr kt hp vi triu chng lm sng c hng iu tr kp thi. Mt khc cn nui cy bnh phm vo cc mi trng thch hp nh canh thang, nc pepton, thch mu, thch thng ..., 28oC . Sau xc nh cc tnh cht sinh vt ha hc, nh typ phage v tim truyn sc vt. 3.2. Chn on gin tip : Bnh dch hch l bnh nhim khun cp tnh nn ngi ta khng lm phn ng huyt thanh chn on bnh. Ngi ta thng lm chn on huyt thanh iu tra dch t hc, thng dng phn ng ngng kt hng cu th ng pht hin khng th khng F1. 4. Phng bnh v iu tr 4.1. Phng bnh 4.1.1 Phng bnh c hiu : Hin nay c hai loi vcxin: vc xin sng gim c v vcxin cht. Vcxin cht tim hai ln, gy min dch c 6 thng. Vc xin sng gim c tim mt ln, gy min dch nhanh v thi gian min dch ko di n mt nm. Ch tim vc xin cho nhng ngi ang sng vng dch hoc phi lm nhim v nhng vng . 4.1.2. Phng bnh chung: Ct t dy truyn dch t bng cch: dit chut, dit cn trng mi gii, bnh nhn phi khai bo v cch ly, phong ta khu vc c dch. Khi c dch xy ra cn phi ung khng sinh d phng cho ngi nh bnh nhn, nhn vin y t tip xc vi th phi. 4.2. iu tr Vi khun dch hch nhy cm vi cc khng sinh nh streptomyxin, chloramphenicol, tetracyclin, nhng phi iu tr sm. Khng sinh penicilin khng c tc dng.

112

II. LEGIONELLA PNEUMOPHILANm 1977 Mac Dade phn lp c t t chc phi ca mt bnh nhn cht v vim phi mt trc khun Gram m mi m trc khoa hc cha bit. Nm 1978, trc khun ny c t tn l Legionella pneumophila. Loi Legionella pneumophila thuc ging Legionella, h Legionellaceae. Chng c kh nng gy bnh ng h hp ngi. 1. c im sinh vt hc 1.1.Hnh th Vi khun a hnh thi, thng gp dng trc khun Gram m (bt mu yu), i khi gp hnh cu trc khun hoc hnh si. Kch thc thay i 0,3-0,9 m x 2- 20 m. Hnh th thay i theo nhng iu kin nui cy v mi trng nui cy khc nhau. Vi khun di ng, c mt lng mt u, khng sinh nha bo, khng c v. 1.2.Tnh cht nui cy Vi khun kh nui cy, hiu kh tuyt i, i hi mi trng giu cht dinh dng vi mt khong pH hp (chung quanh 6,5), t trong kh trng c 2,5 % CO2 v nhit t 3537OC. Mi trng tt nht hin nay phn lp vi khun Legionella pneumophila l mi trng BCYE (Buffered Charcoal Yeast Extract agar), y l mi trng thch c than hat v cao men (cha L- cystein l yu t c bn cho s phn lp Legionella). mi trng ny c cc khun lc rt nh, mu xanh xm d dng quan st knh lp, xut hin vo ngy th 3 sau khi cy. C th nui cy Legionella pneumophila cc nui cy t bo phi g, phi phi ngi, bch cu n nhn to ca ngi, cc t bo HeLa, Hep-2... Nui cy phi g l phng php tt nht thch hp vi tt c cc Legionella thuc cc loi khc nhau. 1.3. Tnh cht sinh vt ha hc Oxydase dng tnh yu, catalase (+), lm lng gelatin, urease m tnh v khng ln men cc loi ng, c kh nng ly gii hippurat natri, th nghim ny dng chn on phn bit vi cc Legionella khc, sinh ra enzyme -lactamase. 1.4. Khng nguyn Khng nguyn O c hiu c chia thnh nhiu nhm huyt thanh khc nhau. Khng nguyn H chung vi cc Legionella khc. 1.5. Sc khng Vi khun d b dit bi tc nhn l ha, nhng li sng lu c trong nc. Vi khun c trong nc t nhin (ao, h), nc cha b v thp nc nhn to. Vi khun c mt trong h thng dn nc nng lnh, h thng my iu ha nhit , cc ng nc, vi nc... 2. Kh nng gy bnh Legionella pneumophila l nguyn nhn ca bnh l vim phi cp v st Pontiac. Vi khun t mi trng xung quanh vo ngi theo ng h hp do ht phi bi hoc hi nc c nhim khun. Bnh vim phi cp do Legionella l mt nhim trng cp tnh ng h hp c vim phi nng vi st cao t ngt, ho, au ngc, a chy, li b hoc m sng... Nu khng c iu tr th t l t vong t 10 % - 20 %. St Pontiac c c trng bi st, rt run, au c v khng c bnh l h hp. Tin trin lnh tnh. bnh vin c nhng v dch bnh xy ra do Legionella pneumophila nhng bnh nhn b bnh nng hoc c iu tr bng cc thuc c ch min dch.

113

Trong nhiu trng hp c nhng nhim trng bn lm sng, ch pht hin c do s tng hiu gi khng th c hiu. Trng hp mc bnh l t, ch yu nhng ngi nghin ht thuc lu nm , b vim ph qun mn v nguy c mc bnh nhng ngi b bnh ung th. Bnh xy ra l t khp mi ni trn th gii. 3. Chn on vi sinh vt 3.1. Chn on trc tip: Pht hin vi khun trong mu nghim (m, cht dch ph qun, mnh sinh thit phi...) bng phng php min dch hunh quang trc tip, y l phng php c hiu, cho kt qu nhanh sau mt vi gi. 3.2. Phn lp vi khun: Bnh phm l mu, mnh phi (sinh thit hoc m t thi), dch mng phi, cht ht t ph qun, kh qun... Vt phm ngoi cnh: ly mu nc. Bnh phm c cy vo mi trng thch BCYE, 36OC trong kh trng c 2,5% CO2. Vi khun mc sau 48 gi. Quan st khun lc v nh danh vi khun. Mi trng cy mu c theo di trong 3 tun, nu vi khun mc cy chuyn vo mi trng BCYE. 3.3. Chn on huyt thanh: Dng cc k thut min dch hunh quang gin tip, ELISA pht hin khng th trong huyt thanh bnh nhn. Cn xc nh khng th trong huyt thanh kp, hiu gi ln hn 4 ln mi c gi tr chn on. 4. Phng bnh v cha bnh. 4.1. Phng bnh: Cn x l nc cc b nc, vi nc, iu ha nhit . Cn c nhng bin php ngn nga khng xy ra dch trong bnh vin. 4.2. Cha bnh: Vi khun nhy cm vi nhiu khng sinh nh erythromycin, rifampicin, fluoroquinolon. Cc -lactamin khng c tc dng trn vi khun ny v chng sn xut enzymee -lactamase.

114

HAEMOPHILUS V BORDETELLAMc tiu hc tp 1.Trnh by c mt s tnh cht vi khun hc ca vi khun Haemophilus v Bordetella. 2.Nu ra c kh nng gy bnh ca hai loi vi khun ny. 3.Trnh by c mt s phng php chn on vi khun hc i vi Haemophilus v Bordetella.

I. HAEMOPHILUSGing Haemophilus thuc h Pasteurellaceae, gm nhng trc khun nh, Gram m, khng di ng, khng sinh nha bo, c v lin quan mt thit vi tnh cht gy bnh. Mi trng nui cy bt buc phi c mt hoc c hai yu t pht trin X v V (X: hematin, V: nicotinamidadenin dinucleotid = NAD). Thch chocolat c c hai yu t ny v thch hp cho s pht trin ca nhng Haemophilus i hi c hai yu t X v V. Cc Haemophilus i hi c hai yu t X v V ch c th pht trin trn mi trng thch mu nu cho thm yu t V bn ngoi vo. Cc Haemophilus k sinh bt buc trn nim mc ng h hp hoc i khi ng sinh dc ca ngi hay ng vt. Thuc nhm ny c nhiu thnh vin, y ch gii thiu Haemophilus influenzae, tc nhn ch yu gy nhim khun h hp cp tr nh v Haemophilus ducreyi, tc nhn gy bnh h cam. 1. Hemophilus influenzae Haemophilus influenzae do Richard Pfeiffer phn lp ln u tin t mt bnh nhn b cht trong v dch cm ln nm 1892 (nn cn gi l trc khun Pfeiffer). T tr i, trong mt khong thi gian di, ngi ta tin rng n chnh l cn nguyn gy ra bnh cm v t tn l Bacterium influenzae. Nm 1933, khi pht hin ra vius cm th cn nguyn ca bnh cm cng nh vai tr ca B. influenzae mi c lm sng t: virus cm gy ra bnh cm, cn B. influenzae l vi khun n theo (second invader) sau khi cc t bo nim mc ng h hp b tn thng nng n bi virus cm. V danh php, thut ng Bacterium influenzae do Lehmann v Neumann xut nm 1896. Nm 1917, Winslow v cng s, trn c s nhng hiu bit mi v B.influenzae, chuyn chng sang ging Haemophilus, v t n nay, chng mang tn Haemophilus influenzae. 1.1. c im sinh vt hc L vi khun a hnh thi, Gram m, khng di ng, khng sinh nha bo. Trong bnh phm vi khun thng c v polysaccharide mang khng nguyn c hiu typ. Trong khi cy truyn trn mi trng nhn to th vi khun mt v. Vi khun hiu kh, i hi CO2 (5 10%), nhit thch hp l 370C, pH thch hp 7,6 - 7,8. Vi khun ch mc c trn mi trng thch c c yu t X v V (mc tt trn mi trng thch chocolat), khun lc nh, trong, mt nhn (dng S), ng knh 0,5-0,8 mm, sau khi cy truyn cc khun lc tr thnh dng R; khng gy tan mu trn thch mu. Trong mi trng nui cy H.influenzae, yu t V c th thay th bng NAD hoc NADP, yu t X c th thay th bng Hemin hoc Hematin. Cng c th thay th yu t V bng cch cy t cu vng trn mi trng thch mu, cc khun lc trong, nh ca H.influenzae mc quanh ng cy t cu khun (do t cu vng tit ra yu t V), l th nghim "v tinh" (Satellitism), c s dng khi khng c yu t V trong mi trng nui cy H. influenzae. H.influenzae ln men ng glucose, khng ln men ng lactose v mannit. H.influenzae khng rt km vi cc yu t ngoi cnh. Trong bnh phm, chng cht nhanh chng nu b nh sng mt tri chiu trc tip, kh hay lnh. H.influenzae b cc cht st khun thng thng git cht mt cch d dng.

115

1.2. Kh nng gy bnh ngi H.influenzae l loi vi khun k sinh bnh thng ng h hp, thng phn lp c nim mc mi hng ngi lnh vi t l khong 25%. N c th gy nn cc nhim khun khc nhau: - Nhim khun ng h hp: H.influenzae typ b l mt trong cc tc nhn ch yu gy cc nhim khun khc nhau ca ng h hp, thng gp tr nh tui. Bnh do H.influenzae thng l th pht (sau si, cm) gm: vim ng h hp trn (thanh qun, tai gia, xoang), vim ng h hp di (vim ph qun cp v mn tnh, vim phi). Vim thanh qun do H.influenzae typ b l chng bnh t gp nhng rt nghim trng. - Vim mng no m tr em: vim mng no do H.influenzae l mt bnh nng v c tnh cht cp tnh, cn c chn on v iu tr ngay. - Ngoi ra H.influenzae cn gy nhim khun huyt, vim ni tm mc (him), vim niu o v cc nhim trng sinh dc (m o, c t cung, tuyn Bartholin, vi trng). 1.3. Chn on vi sinh vt Bnh phm: tu theo bnh cnh lm sng m ly bnh phm khc nhau. Bnh phm c th l m, cht nhy mi hng, cht dch kh qun, ph qun hoc dch no ty, m... 1.3.1. Chn on trc tip - Soi ti, nhum gram i vi dch no tu thy c nhiu bch cu a nhn v vi khun khun gram m a hnh thi. - Tm khng nguyn v typ b trong bnh phm: chn on nhanh cc nhim trng do H.influenzae typ b gy ra. Dng k thut min dch pht hin khng nguyn typ b trong dch no tu, mu v nc tiu. Cc phng php min dch c p dng l min dch i lu, ngng kt th ng, ng ngng kt v ELISA vi khng th n dng. - Tm ADN: dng mt on ADN mu nh du phng x hoc dng k thut khuch i gen (PCR: polymerase chain reaction) tm on ADN c trng ca H.influenzae trong bnh phm. 1.3.2. Nui cy Nui cy bnh phm trn mi trng thch chocolat, bnh kn cha 10% CO 2. Xc nh H. influenzae bng th nghim "v tinh" vi t cu v th nghim vi cc yu t X v V. 1.4. Phng bnh v iu tr 1.4.1. Phng bnh - Phng bnh khng c hiu: vim mng no do H.influenzae typ b l mt bnh ly, bnh nhn cn phi c cch ly. Ngi lnh tip xc vi bnh nhn phi ung khng sinh d phng (Rifampicin). - Phng bnh c hiu: dng vaccine cha polysaccharit v ca H.influenzae typ b (Hib). 1.4.2. iu tr iu tr cc nhim trng do H.influenzae cn phi da vo khng sinh . Trong khi cha c kt qu khng sinh hoc khi khng phn lp c vi khun, chloramphenicol c u tin la chn. Vim mng no cn dng cephalosporin th h 3. 2. Haemophilus ducreyi (Trc khun h cam) c Ducreyi pht hin nm 1889 trong m mn lot c quan sinh dc ca bnh nhn mc bnh h cam, v th c gi l trc khun h cam. Vi khun c t ch tn thng, phi phn lp trn mi trng c 20 - 30 % mu ti, vi khun ch cn yu t X. Bnh nhn mc bnh h cam c phn ng vi hn dch vi khun b git cht tim ni b. Phn ng thng xut hin vo ngy th 8 v tn ti rt lu, c gi tr h tr chn on. Bnh ly qua ng sinh dc nn d phng ch yu l quan h tnh dc hp v sinh v khng quan h vi nhiu ngi. Cha bnh bng khng sinh nh ampicillin, chloramphenicol, bactrim...

116

II. BORDETELLA PERTUSSIS (Trc khun ho g )Trc khun ho g thuc ging Bordetella, h Alcaligenaceae. 1. c im sinh vt hc B. pertussis hnh trc khun rt nho, kch thc 0,5-0,8 m x 0,2-0,3 m, Gram m, khng di ng, khng sinh nha bo, c th c v, vi khun hiu kh. Mun phn lp t bnh phm phi c mi trng c bit, l mi trng Bordet - Gengou (mi trng cha khoai ty, glycerol v 15-20% mu), vi khun mc chm sau 2 - 4 ngy, khun lc nh, trn, li, xm nht nh x c hoc c nh kim loi (ging nh git thy ngn), xung quanh c vng tan mu hp. Catalase m tnh, Oxydase dng tnh, Urease m tnh. Trong qu trnh nui cy trn mi trng nhn to, trc khun ho g bin d t dng S sang dng R. Hin tng ny c chia lm 4 pha : - Pha I: Tng ng vi khun lc dng S, vi khun hnh bu dc, c v, ng ring r hoc tng i, t khi thnh chui, c c lc, c khng nguyn c hiu ca pha I l nhng khng nguyn mnh to c min dch i vi bnh ho g. - Pha IV : Tng ng vi khun lc dng R, vi khun hnh si t o hn v hay xp thnh chui ngn, khng c v, khng c c lc, mt khng nguyn pha I. - Pha II v pha III: l nhng giai on trung gian S bin i pha c ngha quan trng trong sn xut vaccine. Mun iu ch vaccine tt cn phi dng vi khun pha I. Trc khun ho g sn xut cc yu t lm thnh c lc v c vai tr quan trng trong c ch bnh sinh: - c t ho g: bn cht protein, do vi khun pha I tit ra, lm tng lng AMP vng dn n s tng tit dch v cht nhy ng h hp (triu chng c trng ca cn ho trong bnh ho g). Khng th khng c t ho g c vai tr bo v chng nhim trng. - c t Adenylate cyclase: c th xm nhp vo t bo ng h hp lm tng tit AMP vng, c ch hin tng ho hng ng bch cu a nhn trung tnh v c ch hin tng thc bo. c t ny c vai tr bo v vi khun trong giai on sm ca bnh. - c t t bo kh qun (tracheal cytotoxin): gy tn thng c hiu cc t bo lng chuyn ca biu m ng h hp. - c t khng chu nhit v ni c t (lipopolysaccharid): vai tr sinh bnh khng r. - Khng nguyn thn: chu nhit, cn gi l ngng kt nguyn, khng nguyn ny chung cho c ging Bordetella. 2. Kh nng gy bnh ngi B. pertussis gy bnh ho g, thng gp tr em, rt d ly v gy thnh dch. Bnh ho g ly trc tip qua ng h hp, ly nht thi k u ca bnh. Vi khun pht trin lin bo ng h hp, khng vo mu. Vi khun gii phng cc c t gy thng tn ng h hp v gy nn cc du hiu ton thn ca bnh ho g. Bnh ho g l mt bnh nhim khun cp tnh ng h hp, lm vim long ng h hp v xut hin nhng cn ho c bit, gy nhng bin chng phi v no, nh hng ti s pht trin tr tu ca tr, nht l tr s sinh. Bnh ho g xy ra quanh nm, thng gp tr mi n 5 tui. T vong nhiu nht l tr em di 1 tui. Bnh c th gp ngi ln v ch gy ho dai dng khng thnh cn r rt. Ngy nay, nh c vaccine tt t l mc bnh ho g gim rt nhiu. 3. Chn on vi sinh vt 3.1. Chn on trc tip - Ch yu l phn lp vi khun. C nhiu cch ly bnh phm, tt nht l ly bnh phm thi k u ca bnh. Ly bnh phm hng mi bng tm bng mm v n hi qua ng mi, cy vo mi trng Bordet-Gengou ngay ti ging bnh nhn. C th dng mt da mi trng m ra v cch ming bnh nhn 10cm hng nc bt bn ra trong cn ho

117

khng kch thch khong 15 giy. t m 370C/ 2-3 ngy. Xc nh khun lc in hnh, nhum gram xc nh hnh th vi khun v lm phn ng ngng kt vi khng huyt thanh c hiu. Ngoi ra, c th dng khng th n dng tm c t ho g trong bnh phm, dng k thut khuch i gen (PCR: Polymerase Chain Reaction) tm on ADN c hiu ca vi khun. 3.2. Chn on gin tip Tm khng th khng c t ho g trong huyt thanh bnh nhn. 4. Phng bnh v iu tr 4.1. Phng bnh 4.1.1. Phng bnh khng c hiu: Pht hin bnh sm v cha tr kp thi, cch ly bnh nhn v hn ch tip xc nht l nhng bnh nhn ang thi k u ca bnh. 4.1.2. Phng bnh c hiu Vaccine ho g hin nay l vaccine cht, c lm t vi khun ho g pha I. Dng vaccine ho g tim ng lot cho tr em di 1 tui gy min dch c bn. Tim nhc li sau 1 nm cng c min dch v sau 5 nm tim nhc li mt ln na. Vaccine phng bnh ho g l mt trong 6 loi vaccine bt buc trong chng trnh tim chng m rng, thng dng di dng 1 vaccine hn hp Bch hu-Un vn-Ho g (DTC: Diphterie-TetanieCough). Ngoi ra c th dng huyt thanh min dch hoc globulin min dch ngi phng bnh v cha bnh ho g tr cn b. 4.2. iu tr Phi pht hin sm cch ly v iu tr ngay bng khng sinh. Liu php khng sinh khng rt ngn c giai on kch pht nhng loi tr c vi khun gy bnh, gim ly lan, d phng bi nhim. Khng sinh chn lc l erythromycin.

118

TRC KHUN M XANH V BURKHOLDERIA PSEUDOMALLEIMc tiu hc tp 1.Trnh by c c im sinh vt hc ca trc khun m xanh v Burkholderia pseudomallei 2.Trnh by c kh nng gy bnh ca hai vi khun ny 3.Trnh by c phng php chn on sinh vt hc, phng php phng nga v iu tr Trc khun m xanh v Burkholderia pseudomallei thuc h Pseudomonadaceae , h ny bao gm nhng trc khun Gram (-), hiu kh, di ng bng mt hoc nhiu lng mt u (tr Burkholderia mallei khng di ng), chng chuyn ha nng lng bng hnh thc oxy ha carbohydrate, khng ln men cc loi ng. C enzyme oxydase v enzyme catalase. Chng phn b rng ri trong thin nhin, ch mt s loi c kh nng gy bnh ngi, ng vt hoc thc vt.

I. TRC KHUN M XANH (Pseudomonas aeruginosa)Pseudomonas aeruginosa thng tm thy trong t, trong nc hoc trn c th ngi v ng vt. Trc khun m xanh l tc nhn chnh ca nhim trng bnh vin v cc nhim trng c hi. 1. c im sinh vt hc 1.1. Hnh th Trc khun Gram m, kch thc thay i thng thng nh v mnh, 1,5 - 3 m, thng hp thnh i v chui ngn, rt di ng, c lng mt u, him khi to v v khng to nha bo. 1.2. Nui cy Vi khun hiu kh, mc d dng trn cc mi trng nui cy thng thng nh thch dinh dng, thch mu, canh thang. Nhit thch hp 30 - 37 0C, nhng c th pht trin c 410C. pH thch hp l 7,2-7,5. Khun lc thng ln, trong, b u hoc khng u, c th c nh kim loi, mu xm nht trn nn mi trng mu hi xanh, mi thm. Cng c th gp loi khun lc x x hoc nhy. Tnh cht c trng ca trc khun m xanh l sinh sc t v cht thm. Trn mi trng nui cy c pepton, vi khun c th tit ra cc loi sc t sau : -Pyocyanin: l loi sc t phenazin c mu xanh l, tan trong nc v chlorofoc, khuch tn ra mi trng nui cy lm cho mi trng v khun lc c mu xanh. Sc t ny sinh ra thun li trong mi trng tip xc nhiu vi khng kh. Ch c trc khun m xanh sinh sc t pyocyanin. -Pyoverdin: l loi sc t hunh quang, pht mu xanh khi chiu tia cc tm c bc sng 400 nm, tan trong nc nhng khng tan trong chlorofoc. Ngoi trc khun m xanh cn c mt s loi Pseudomonas khc to thnh sc t ny. -Pyorubrin: sc t mu hng nht, ch 1% s chng trc khun m xanh sinh ra sc t ny. -Pyomelanin: sc t mu nu en, ch 1-2% s chng trc khun m xanh sinh sc t ny. C khong 5-10% s chng trc khun m xanh khng sinh sc t. 1.3. Tnh cht sinh ho

119

Trc khun m xanh c oxydase dng tnh(+), lm lng gelatin, kh NO3 thnh N2. S dng carbohydrat theo li oxy ho c sinh axit nh glucose, mannitol, glycerol, arabinose...Lactose m tnh (-), Citrat simmon dng tnh(+), ADH dng tnh(+) ; Urease m tnh(-), indol m tnh(-), H2S m tnh(-). 1.4. Khng nguyn Vi khun c khng nguyn lng H khng bn vi nhit v khng nguyn O chu nhit. Da vo khng nguyn O, ti nay ngi ta chia trc khun m xanh lm 16 typ huyt thanh. Cng c th nh typ phage nhng thng nh typ bacterioxin (pyocin) trong cc v dch. Cng nh cc trc khun ng rut, khng nguyn O ca trc khun m xanh mang ni c t bn cht gluxit-lipit- protein. Nhng trong c ch sinh bnh quan trng hn l ngoi c t. Trong 3 loi ngoi c t do vi khun to thnh ngoi c t A c xem nh l nhn t ch yu v c lc, n khng bn vi nhit, git cht chut nht, chut ln v cn tr s tng hp protein tng t nh c t bch hu. 2. Kh nng gy bnh Trc khun m xanh l loi vi khun gy bnh c iu kin. V vy him gp nhim trng Pseudomonas aeruginosa ngi bnh thng tr nhim trng th pht nh vim tai ngoi mn. Nhim trng thng xy ra nhng ngi m c ch bo v b tn thng nh s dng corticoid hoc khng sinh di ngy, bng nng hoc tim tnh mch ma ty... V tr nhim trng thng thng l ng tiu v vt thng h (nht l vt bng). Ti ch xm nhp chng gy vim c m (m c mu xanh), c th suy gim sc khng chng c th xm nhp vo su hn trong c th v gy vim cc ph tng nh cc nhim trng nung m v nhng p xe nhng phn khc nhau c th ngi. Nhng trng hp vim mng trong tim, vim phi, vim mng no tuy him nhng cng xy ra hoc gy bnh ton thn (nh nhim khun huyt, nhim khun tr mi hoc non thng bnh rt trm trng). Nhim khun mu thng gy cht xy ra ngi suy nhc. Nhng nm gn y nhim trng trc khun m xanh tr nn quan trng do :iu tr v phng nga nhng nhim trng khc bng nhng khng sinh m n khng, s dng cc thuc corticoit, thuc chng chuyn ho v thuc gim min dch lm cho gim st sc khng ca c th, s dng cc dng c thm khm nh ng thng v cc dng c khc thm d cha c kh khun tt, s dng ngy cng rng ri mu v cc sn phm ca mu m ta khng th kh khun c trong khi cc cht ny c th b nhim Pseudomonas. Trc khun m xanh l mt tc nhn nhim trng bnh vin ng lu : nhim trng sau m v bng nng. Nhim trng trc khun m xanh trong nhng trng hp c th gy cht. T l t vong do nhim trng mu c th vt qu 80%. 3. Sinh l bnh hc Mt s tc gi chng minh rng trc khun m xanh gy bnh c l do: - Mt c t to thnh t mt hn hp cht c gm: dung huyt t, protease, lexitinase. - Khng nguyn nhy xung quanh vi khun gm mt ADN gn vi gluxit- lipit prtein ca khng nguyn O (ni c t) ca vi khun. Khng nguyn ng vai tr quan trng trong c lc ca vi khun (c th so snh vi vai tr ca ni c t). 4. Chn on Bnh phm l m ca cc vt thng b bi nhim, cht dch ph qun, nc tiu, dich mng phi... Trong chn on dch t hc: dch chuyn, dch ra vt thng, dng c ngoi khoa... l mu nghim. Mu nghim c cy ln mi trng thng thng nh thch dinh dng hoc mi trng c cht c ch nh mi trng Cetrimide. 37 0C trong kh trng thng.

120

Chn khun lc dt, ln, b khng u, b mt c nh kim loi, to sc t ha tan nhum xanh khun lc v nhum xanh mi trng xung quanh khun lc. Xc nh vi khun da vo trc khun Gram (-), khng sinh nha bo, oxidase (+), chuyn ho ng theo kiu oxy ho, c bit khun lc c mi thm v sinh sc t nhum mu mi trng xung quanh khun lc. i vi cc chng khng sinh sc t cn cy vo cc mi trng tng sinh sc t nh: King A (tng sinh pyocyanin) v King B (tng sinh pyoverdins). Ngi ta c th s dng nhng k thut khc nhau xc nh c ngun gc ca cc chng trc khun m xanh trong cc nhim trng bnh vin. 5. Phng nga v iu tr Nhim trng do Pseudomonas aeruginosa kh iu tr v khng vi nhiu khng sinh. Nhng chng thng gp cho thy vi khun thng khng vi 3 khng sinh hoc hn. Trong iu tr phi lm khng sinh . Hin nay thng s dng tobramycin, amikacin, carbenicillin, cefaperazon, ceftazidim. Gn y min dch liu php hot ng v th ng c s dng bnh nhn bng vi kt qu kh tt. Nhim trng ti ch c th ra vi 1% axt axetic hoc bi thuc m Colistin hoc Polymycin B.

II. BURKHOLDERIA PSEUDOMALLEI (Trc khun Whitmore)B. pseudomallei l tc nhn gy ra bnh Melioidosis, mt bnh thng gp vng ng - Nam chu . Bnh Melioidosis thng nng, t l t vong cao do chn on lm sng kh khn, bnh hay ti pht v do B. pseudomallei khng li nhiu khng sinh. 1. c im sinh vt hc 1.1. Hnh th Trc khun Gram m ngn, bt mu thuc nhum mnh hai u, ng ring l hoc chui ngn, i khi c hnh dng cu trc khun. Kch thc 0,8 x1,5 m. Vi khun di ng c mt chm lng mt u, khng sinh nha bo. 1.2. Tnh cht nui cy Vi khun mc c cc mi trng nui cy thng thng, kh phn lp nui cy ln u. Hiu kh, nhit thch hp 370C, nhng c th pht trin c t 5-420 C v mi trng c 3% NaCl. Trn mi trng lng, vi khun mc bng cch to vng, theo thi gian vng cng dy. Trn mi trng c, to khun lc kh, b my nhn nheo, b rng ca, mu trng c hoc mu kem. C th quan st thy nhiu dng khun lc c kch thc v hnh thi khc nhau trn cng mt mi trng. B. pseudomallei khng sinh sc t ho tan. Nui cy to ra mi thm (ging mi nho). 1.3. Tnh cht sinh ho Oxydase dng tnh(+), catalase dng tnh(+). S dng carbohydrat theo li oxy ho sinh axit nh: arabinose, dulcitol, glucose, lactose v mannitol, lm lng gelatin, ADH (arginin ihydrolase) dng tnh(+), citrat simmon dng tnh(+), indol m tnh(-), kh nitrat thnh N2 , di ng mnh. 1.4. Sc khng B. pseudomallei c mt trong t nhin, c bit c tm thy trong cc cnh ng la nc vng ng Nam . Chng sng hng tun n hng thng ni m nu gp iu kin thch hp nh khng c nh sng mt tri v lnh. 1.5. Min dch Do vi khun phn b rng ri trn ng rung, 30-50% nng dn kho mnh sng trong vng B. pseudomallei lu hnh c khng th chng vi khun ny. Khi b bnh, khng th tng cao v cn tn ti vi thng sau khi khi bnh. Tuy nhin, khng th ny khng c vai tr bo v, bnh nhn c th b ti nhim hoc ti pht mt cch d dng.

121

2. Kh nng gy bnh 2.1. ngi Vi khun gy bnh Mlioidosis thng gp Min in, Thi Lan, Vit Nam, Lo, Campuchia, Indonesia v chu c. Vi khun xm nhp vo c th ch yu qua vt thng, nhng ch sy st trn da. Ti ni xm nhp chng hnh thnh nhng mn m nh, c khi to thnh mt p xe rt ln. nhng ngi suy gim min dch, mc cc bnh mn tnh ko di vi khun thng vo mu v gy ra bnh cnh lm sng nng ca mt nhim khun huyt. T mu vi khun n cc ph tng gy nn p xe nh nhiu c quan nh phi, thn, gan, lch. Sau cc p xe nh to thnh cc p xe ln gy ra cc triu chng lm sng nhiu c quan khc nhau. Vi khun c th sng trong cc i thc bo, iu ny c th gii thch nhng trng hp bnh ti pht. Bnh c th din bin cp tnh, bn cp v mn tnh - Th cp tnh nhim khun huyt vi a chy v st c tnh, thng cht trong vi ngy. - Th ban cp dng thng hn vi p xe phi, thn, gan, c, cht sau vi tun l. - Th mn tnh c th khu tr (p xe xng hoc da) hoc nhim khun huyt kiu ln sng. 2.2. Kh nng gy bnh thc nghim Ngi ta c th gy bnh c cho phn ln cc ng vt nh th, chut lang, chut nht, nga bng nhiu ng khc nhau: qua da, tim tnh mch, tim phc mc hoc ng h hp. Bnh melioidose sc vt c th ly sang ngi. 3. Chn on vi sinh vt 3.1. Phn lp vi khun Bnh phm l m p xe, mn m, mu trong nhim khun huyt, m trong vim ph qun, dch mng phi, dch mng tim...Cy bnh phm vo mi trng nui cy thng thng nh thch thng, thch mu, canh thang hoc mi trng chn lc c cha gentamicin. Xc nh vi khun da vo hnh th, tnh cht bt mu, hnh thi khun lc v tnh cht sinh ha. 3.2. Chn on huyt thanh - Trong iu tra dch t hc: dng phn ng ngng kt hng cu th ng tm khng th ngng kt - Trong chn on bnh: dng phn ng ngng kt hng cu th ng v ELISA vi khng nguyn protein 4. Phng nga v iu tr 4.1. Phng bnh Hin nay cha c vaccine. Tng cng sc khng chung, gi gn v sinh, trnh cc tn thng da trong khi lm vic ni c vi khun. 4.2. iu tr Dng khng sinh nh tetracyclin, chloramphenicol, bactrim, ceftazidim. V vi khun ln trnh trong t bo nn cn lu chn la khng sinh khuch tn tt vo trong t bo v dng trong thi gian di phng nga ti pht. Vi khun khng gentamycin, ampicillin, polymycin. Dng bin php chc ht m p xe, tng cng sc khng, iu tr triu chng.

122

VIBRIOMc tiu hc tp 1.Trnh by c cc c im sinh vt hc. 2.Trnh by c kh nng gy bnh ca vi khun t v V.parahaemolyticus. 3.Trnh by c phng php chn on vi sinh vt. Ging Vibrio thuc vo h Vibrionaceae. Chng l nhng vi khun hnh que hi cong nh du phy, Gram m, khng sinh nha bo, di ng nh mt lng mt u, oxydaza dng tnh ... Ging Vibrio c chia thnh : - Vibrio cholerae O1: thuc nhm huyt thanh O1 c kh nng sinh c t rut v gy ra bnh dch t. Vibrio cholerae O1 bao gm tp sinh hc c in v tp sinh hc El Tor. Cc sinh tp ny ngng kt vi khng huyt thanh nhm 01. Trong nhm ny c 3 tp huyt thanh l Ogawa, Inaba v Hikojima. - Vibrio cholerae khng phi O1/ khng phi O139: bao gm cc nhm huyt thanh t O2 - O138 khng c kh nng gy dch t. C tnh cht sinh ha tng t nh V.cholerae O1 nhng khng ngng kt vi khng huyt thanh O1. Cc nhim trng do nhm ny thng lin quan n mi sinh, chng gy ra vim rut cp nhng c ch gy bnh vn cha c gii thch. - Vibrio cholerae O139: l tc nhn gy ra bnh dch t c pht hin ln u tin vo nm 1992 ti n v Bangladesh. c lc ca n l c t rut v khng nguyn pili ng iu ha c t (Toxin coregulated pili - TCP). - Cc Vibrio khc : V. mimicus; V. parahaemolyticus; V.hollisae. V. fluvialis; V.furnissii; V.vulnificus; V.alginolyticus; V.damsela; V.cincinnatiensis; V.metschnikovii.

I. VI KHUN T (Vibrio cholerae)1. c im sinh vt hc 1.1. Hnh th Vi khun t hnh que ngn, hi cong hnh cung hoc hnh du phy, Gram m, rt di ng nh mt lng u, khng c v, khng sinh nha bo. 1.2. Tnh cht nui cy Vi khun t rt hiu kh, mc c trn cc mi trng dinh dng thng, pH kim. Thng dng nc pepton pH 8,5 , mi trng thch TCBS (thiosulfate - Citrate - Bile salt) pH 8,6 , TTGA (Taurocholate - Tellurite - Gelatin Agar) pH 8,5 nui cy phn lp vi khun t. 1.3. Tnh cht sinh vt ha hc Vi khun t c oxidase, ln men khng sinh hi glucose, saccharose, D-mannitol, maltose, khng ln men arabinose. Phn ng indol dng tnh, phn ng Voges-Proskauer m tnh i vi sinh tp c in v dng tnh i vi sinh tp El Tor. 1.4. Cu trc khng nguyn - Khng nguyn thn O: bn cht l lipopolysaccharide. N quyt nh tnh sinh min dch ca vaccine t c in (vaccine t cht). Ngi ta phn bit thnh nhiu nhm huyt thanh O. V.cholerae sinh tp c in v sinh tp El Tor thuc nhm huyt thanh O1. Trong nhm O1 c 3 tp huyt thanh : Ogawa, Inaba v Hikojima.

123

- Khng nguyn lng H: Khng c gi tr trong thc tin. - Khng nguyn c t rut bn cht l protein, c t rut ca V.cholerae 01 kch thch c th sinh khng c t. 1.5. Sc khng Vi khun t cht nhit 100oC hoc 80oC/5 pht v b tiu dit bi cc ha cht nh cloramin, cresyl, vi cc ... Kh hanh v nh nng mt tri cng lm vi khun d cht. Trong nc , nc bin, nc ao h vi khun sng c vi ngy. 2. Kh nng gy bnh 2.1. Sinh bnh hc Cc vi khun t xm nhp c th bng ng tiu ha, chng phi vt qua hng ro dch v ca d dy c pH axt xung rut non l ni c pH thch hp cho s pht trin ca vi khun. axt bnh thng ca dch v l mt cn tr rt ln i vi qu trnh sinh bnh ca vi khun t. Vo n rut non, V.cholerae bm dnh vo t bo nim mc rut nh c cc yu t bm dnh nh khng nguyn TCP, khng nguyn ngng kt hng cu nhy cm vi mannoza..., vi khun nhn ln v tit ra c t rut. Cc vi khun khng xm nhp vo trong cc t bo nim mc rut. c t rut ca vi khun t l mt protein gm 2 tiu phn A (Active) v B (Binding) c chc nng ring bit. Tiu phn A c hai tiu n v A1 v A2, tiu phn B c 5 tiu n v B1, B2, B3, B4 v B5. Tiu phn B c chc nng gn c t rut vo th th ganglioside GM1 trn mng ca t bo nim mc rut, cn tiu phn A m ch yu l A 1 xm nhp vo bn trong t bo hot ha enzymee adenylate cyclase, lm tng nng AMP vng ni bo lm cho t bo nim mc rut gim hp thu Na+, tng tit nc v Cl-, gy ra a chy cp tnh. Nu khng c iu tr tch cc bnh nhn s cht v kit nc v mt cc cht in gii. c t t cn gy nn c ch min dch t bo bng cch tc ng trc tip ln macrophage v t bo lympho T. Trong qu trnh sinh bnh t, c t t v vi khun t khng gy nn thng tn nim mc rut. V vy c ch hp th li mui, nc v glucose vn nguyn vn. y l c s sinh l cho vic b dch bng ng ung dung dch c in gii v glucose (ORESOL) c tc dng tt (glucose y nhm to iu kin hp th li Na cao hn, ch khng phi l cung cp nng lng). 2.2. Kh nng gy bnh Trong iu kin t nhin bnh thng, V.cholerae ch gy bnh t cho ngi. Bnh t l mt bnh nhim trng nhim c cp tnh, ly rt mnh gy thnh dch ln. Thi gian bnh t 2 n 5 ngy. Du hiu c trng ca thi k ton pht ca bnh l tiu chy v nn, phn lng v trng nh nc vo go. Bnh nhn mt nc, mt mui rt nhanh, c th mt 1 lt nc trong 1 gi do ch vi gi l xut hin hi chng mt nc cp tnh lm cho ton thn st i rt nhanh v rt nng. Nu khng c iu tr, t l cht rt cao (50 n 60%). Lm sng bnh t c nhiu biu hin rt khc nhau t th nh d b qua cho n th nng vi hi chng t in hnh. 2.3. Min dch p ng min dch dch th trong bnh t lm xut hin IgG trong mu v IgA tit nim mc rut. Cc khng th ny chng li vch t bo vi khun, ngn cn vi khun bm dnh vo nim mc v chng li c t t, ngn cn c t t (tiu phn B) gn vo mng t bo nim mc rut. 2.4. Dch t hc Bnh t ly truyn qua ng tiu ha qua thc n, nc b nhim khun. Ngun truyn nhim l ngi bnh v ngi lnh mang vi khun t.

124

K t nm 1817 cho n nay trn th gii xy ra 7 i dch t. Su i dch t u do V.cholerae sinh type c in gy nn. i dch t ln th 7 do V.cholerae sinh tp El Tor gy nn, bt u t nm 1961 ko di cho n ngy nay. V.cholerae El Tor khng vi tc nhn ha hc, tn ti lu hn ngi v sng trong thin nhin lu hn V.cholerae sinh tp c in. Ngoi ra i vi vng bnh t El Tor lu hnh th nhng trng hp nng thng t hn v nhng trng hp nh khng triu chng li nhiu hn. Bt u t nm 1992 dch t xy ra Madras v nhiu ni khc thuc n v Bangladesh do Vibrio cholerae O139 gy nn vi c ch bnh sinh hon ton ging nh Vibrio cholerae O1. Sau dch t do chng O139 ly lan ra cc nc khc. 3. Chn on vi sinh vt 3.1. Chn on trc tip Bnh t l mt bnh cp tnh nn cy phn phn lp vi khun t l phng php chn on tt nht. 3.1.1. Bnh phm Ly phn sm ngay trong thi k u ca bnh trc khi iu tr khng sinh. Bnh phm phn cn a ngay v phng xt nghim trong vng 2 gi. Nu gi bnh phm i xa phi cho vo mi trng bo qun v vn chuyn Cary Blair, v a v phng xt nghim cng sm cng tt. 3.1.2. Xt nghim knh hin vi Soi ti c th thy vi khun t di ng rt nhanh. Nhum Gram thy nhiu phy khun Gram m. Xt nghim bnh phm knh hin vi c tc dng chn on s b. 3.1.3. Nui cy Bnh phm c cy vo cc mi trng chn lc v mi trng phong ph phn lp vi khun. Xc nh tnh cht sinh vt ha hc. Lm phn ng ngng kt trn phin knh vi khng huyt thanh a gi O1 v vi khng huyt thanh n gi c hiu tp Inaba hoc Ogawa xc nh chn on. 3.1.4. Phng php chn on nhanh xc nh nhanh vi khun t c th dng cc k thut nh bt ng vi khun, khng th hunh quang trc tip. 3.2. Chn on gin tip Phng php chn on huyt thanh khng gip ch cho chn on bnh. N c th c dng trong iu tra dch t hc. 4. Phng bnh v cha bnh 4.1. Phng bnh 4.1.1. Phng bnh chung - Gim st dch t hc, ch ng pht hin ngun bnh sm, kp thi cch ly, bao vy v x l. - Lm sch mi trng sng bng cc bin php nh x l rc v nc thi theo ng yu cu v sinh; kim tra v sinh thc phm; thc hin n chn ung si v sch ... 4.1.2. Phng bnh c hiu - Vaccine cht, dng ng tim trong da, c hiu lc thp v thi gian bo v ngn. Hin nay nhiu nc khng s dng loi vaccine c in ny. - Vaccine sng gim c lc: to ra cc chng t bin khng c lm vaccine ung. Hin nay ang th nghim.

125

- Vaccine cht, ung: Loi vaccine ny c th dng ton t bo bt hot n thun hoc dng kt hp vi tiu n v B ca c t t c tinh ch. Vit Nam dng loi vaccine t ng ung n lin cha cc t bo Vibrio cholerae O1 c in v El Tor c bt hot bng nhit v formalin. Hin nay ang th nghim loi vaccine t bt hot (Vaccine biv-WC) gm c Vibrio cholerae O1 v Vibrio cholerae O139. 4.2. Cha bnh Phi b nc v in gii sm, nhanh v cho bnh nhn. Dng khng sinh Tetracycline, Doxycycline ...

II. VIBRIO PARAHAEMOLYTICUSV.parahaemolyticus c phn lp ln u Nht Bn nm 1950 t phn bnh nhn tiu chy do n c bin. 1. c im sinh vt hc V.parahaemolyticus c hnh hi cong v ngn. Gram m v di ng. L vi khun a mn (halophile) tn ti trong nc bin v cc ng vt bin nh c, tm, s, c ... Vi khun mc tt mi trng kim v mn. Nhit thch hp cho s nhn ln l 37 o C. V.parahaemolyticus c oxidase dng tnh, ln men D-mannitol, maltose, L.arabinose, khng ln men saccharose. V.parahaemolyticus b cht 65 o C sau 10 pht, chng khng pht trin c nhit di 15 o C. Vi khun c 3 loi khng nguyn : + Khng nguyn thn 0 : chu nhit, c chia thnh 12 type. + Khng nguyn lng H. + Khng nguyn v K : khng chu nhit, c chia thnh 59 type. 2. Kh nng gy bnh V.parahaemolyticus l mt trong nhng nguyn nhn gy nhim trng nhim c thc n. Ngi mc bnh ch yu l do n phi thc n hi sn cha c nu chn hoc b nhim khun trong qu trnh ch bin v bo qun. Thi gian bnh bnh ngn t 2 - 6 gi. Bnh biu hin cc triu chng nn v tiu chy kiu t nh hoc tiu chy kiu l trc khun. Bnh do vi khun ny gy ra gp nhiu nht Nht Bn, ngoi ra cn gp nhiu nc khc. Vit Nam gp nhiu ln ti vng b bin Bc B. 3. Chn on vi sinh vt - Phn lp vi khun t bnh phm l phn, cht nn ca bnh nhn. - Phn lp vi khun t cc hi sn trong trng hp iu tra thc phm nhim khun. 4. Phng bnh v cha bnh - Cha c vaccine phng bnh. - Phng bnh chung bng cch nu k thc n hi sn, khng n sng hi sn. - iu tr bng cc khng sinh nhy cm nh tetracycline, chloramphenicol ...

126

CAMPYLOBACTER V HELICOBACTERMc tiu hc tp 1. Trnh by c mt s tnh cht vi khun hc ca Campylobacter v Helicobacter. 2. Nu c kh nng gy bnh ca cc vi khun ny. 3. Trnh by c mt s phng php chn on vi khun hc i vi Campylobacter v Helicobacter.

I. CAMPYLOBACTER JEJUNIGing Campylobacter thuc h Spirillaceae, gm c cc loi khc nhau c th gy bnh cho ngi. 1. c im sinh vt hc Campylobacter jejuni l nhng vi khun b, mnh, Gram m, hnh du phy nhn hai u, rt di ng nh c 1 lng 1 u, khng sinh nha bo. Nui cy C.jejuni trn mi trng nhn to thng kh khn v vi khun i hi iu kin vi hiu kh (micro-aerophile). Mc c 37 o C nhng mc tt hn 42 o C, khng mc 25 o C. Thng dng cc mi trng chn lc nh thch mu Columbia, thch mu tryptose phn lp vi khun. C.jejuni mc chm sau 2 - 3 ngy. Vi khun c Oxydase v Catalase, phn hy nitrat, khng oxy ha hoc khng ln men cc loi ng. C.jejuni c khng nguyn O chu nhit c chia thnh 23 typ huyt thanh v c khng nguyn H khng chu nhit. 2. Kh nng gy bnh C.jejuni l mt tc nhn gy vim rut cp tnh thng gp ngi. Chng xm nhp vo ngi do n ung cc thc n v nc b nhim khun, do tip xc vi ng vt, ch yu l vi gia cm, gia sc. Thi gian bnh 2-10 ngy. Th lm sng thng gp l bnh cnh ca mt vim rut cp tnh vi du hiu au bng, tiu chy d di, phn nc c khi c mu v m. C trng hp xy ra nhim khun huyt. Tiu chy do C.jejuni ko di 5-10 ngy. a s trng hp khi khng cn iu tr bng khng sinh. C ch gy bnh cha r. C.jejuni c c t rut, nhng c kin cho rng vi khun ny c kh nng xm nhp ging nh Shigella. C.jejuni nhn ln ch yu hi trng v hng trng. Bnh vim rut do C.jejuni xy ra nhiu ni trn th gii, gy tiu chy cp ngi, c bit tr em v khch du lch t cc nc pht trin n cc nc nhit i. 3. Chn on vi sinh vt Chn on vim rut cp do C.jejuni phi da ch yu vo phn lp vi khun t phn ca bnh nhn. Cy phn vo cc mi trng chn lc, nhit 42oC t 2 - 3 ngy trong kh trng c 5% oxy, 10% cacbonic v 85% nit. 4. Phng bnh v iu tr Cha c vaccin. Cn ch v sinh mi trng, v sinh n ung. Khng sinh ch nn dng trong nhng trng hp nhim khun huyt hoc tiu chy ko di.

II. HELICOBACTER PYLORIT nm 1900 n nm 1980, thnh thong ngi ta ghi nhn c s hin din ca mt vi khun hnh xon nim mc d dy. Nhng nhng pht hin khng c quan tm ng mc, bi v cho n cui th k 20 ny, hu nh ngi ta vn quan nim rng d dy l mi trng khng c vi khun do pH acid ca n. Mi n nm 1979, Warren a ra gi thuyt chnh vi khun l cn nguyn gy ra vim, lot d dy - t trng. Nm 1981, Marshall bt u tm ra phng php phn lp vi khun ny, n nm 1982 ng nui cy thnh cng v thy vi khun ny ging nh Campylobacter jejuni , nm 1983 ng chnh thc

127

cng b vi khun ny trn tp ch Lancet (Paris) vi tn l Campylobacter pyloridis, v sau c gi l Campylobacter pylori. Nm 1989, Goodwin nghin cu v cu trc t bo vi khun ny v thy chng khc hn cc Campylobacter khc nn ngh xp cc Campylobacter ny thnh mt ging mi, ging Helicobacter v t Campylobacter pylori c gi l Helicobacter pylori. 1. c im sinh vt hc L nhng vi khun nh, lc mi phn lp t mu sinh thit nim mc d dy th c hnh cong, hoc hnh ch S, ng thnh m. Nu cy chuyn nhiu ln th c hnh que. Vi khun Gram m, rt di ng nh c 2-6 lng mt u. Vi khun khng sinh nha bo. Vi khun i hi iu kin vi hiu kh. Yu cu dinh dng cao, mi trng nui cy cn c mu ng vt hoc huyt thanh. Vi khun mc chm, trn mi trng thch mu Colombia hoc thch mu tryptose sau 3 ngy 37 oC, c th thy khun lc nh, khng mu, c nh nhn. Vi khun khng ln men cc loi ng, c oxydase v catalase, urease dng tnh mnh. Urease dng tnh mnh l tnh cht dng phn bit H. pylori vi cc vi khun c hnh cong khc nh Campylobacter... 2. Min dch 2.1. p ng min dch ti ch Ti ni H. pylori xm nhp, xut hin hin tng tp trung mt s lng ln cc bch cu trung tnh v cc t bo lympho. Cc t bo lympho v bch cu gii phng ra cc interleukin v cc gc t do oxy ho, nhng phn ng vim ti ch ny khng c kh nng loi b H. pylori. 2.2. p ng min dch dch th Khi nghin cu tm khng th trong mu nhng bnh nhn lot d dy - t trng c mt H. pylori, ngi ta pht hin thy c s gia tng khng th IgG, IgA v c bit l IgM. Cc khng th ny gim mt cch c ngha sau khi tit tr ht H. pylori. Vn ny c ng dng trong chn on huyt thanh hc v gim st kt qu iu tr. 3. Kh nng gy bnh ngi 3.1. Kh nng gy bnh T khi Marshall phn lp thnh cng vi khun ny, nhiu cng trnh nghin cu v vai tr gy bnh ca H. pylori c thc hin. Ngi ta cng tin hnh nghin cu trn ngi tnh nguyn, y l nhng ngi khng c hi chng vim, lot d dy; h c ung H. pylori. Sau mt thi gian, h b vim d dy; sau ngi ta li dng cc bin php tiu dit H. pylori th nhng ngi ny li ht vim d dy. Gn y, nhiu tc gi nhn xt rng, hu nh cc trng hp vim lot d dy - t trng u lin quan n nhim trng H. pylori; c bit trong th vim teo, mt th rt d dn n ung th d dy m li thy lun lun c mt vi khun ny. 3.2. C ch gy bnh H. pylori rt di ng, xm nhp qua lp cht nhy v xm ln biu m d dy, c bit l khong gian bo. Vi khun sn sinh urease rt mnh, enzyme ny c hot tnh phn gii ur thnh amoniac. Ur l sn phm chuyn ho ca cc m t bo, chng vo mu mt phn v c o thi ra ngoi qua thn. Mt lng ur t mu qua lp nim mc d dy vo dch d dy. Amoniac c phn ng kim lm tng tm thi pH ti ch n khong 6,5 v gip cho vi khun sng st c trong mi trng rt axit ca d dy. Ngoi ra amoniac cn gy c trc tip i vi t bo nim mc d dy. H.pylori cn lm gim cht nhy bo v thnh d dy cho nn axit dch v tc ng trc tip ln thnh d dy. S phi hp nhiu yu t trn gy vim, let d dy. Trn nhng bnh nhn b vim let d dy - t trng c th phn lp c H.pylori t 80%-90% trng hp. 3.3. Dch t hc

128

Tnh trng kinh t ca x hi c nh hng ln n hin tng nhim H. pylori. Ngay M, t l nhim H. pylori ngi da en cng cao hn ngi da trng, bi v lin quan n i sng tinh thn, vt cht v v sinh mi trng. Ngun truyn nhim l ngi, c th gp kh nhng khng ng k. ng ly ch yu l ngi truyn sang ngi. Phng thc ly truyn l ng phn - ming v ng ming - ming, trong ng phn - ming ng vai tr ch yu. 4. Chn on vi sinh vt 4.1. Chn on trc tip Phn lp vi khun t bnh phm, bnh phm thng thng nht l mu sinh thit nim mc d dy khi ni soi, hoc c th l dch d dy. Nui cy ln cc mi trng thch hp nh thch mu Colombia, 37oC iu kin vi hiu kh, sau 3 ngy thy khun lc nghi ng th trch bit ri nhum Gram (cn thay th Safranin bng Fuchsin mu c r hn do vi khun nh), th nghim cc tnh cht sinh vt ha hc xc nh vi khun. 4.2. Chn on nhanh bng test ureaza Cho mu sinh thit vo mi t