micro lec 17 - yersinia

8/2/2019 Micro Lec 17 - Yersinia

1/24

FACULTAS MEDICINAE ET CHIRURGIAE

PRAYER BEFOREPRAYER BEFORE

CLASSCLASS

Oh Lord Our God,Oh Lord Our God,May the inpouring of the Holy SpiritMay the inpouring of the Holy Spirit

Purify our hearts andPurify our hearts and

make them fruitful by themake them fruitful by the

sprinkling with the dew of His grace.sprinkling with the dew of His grace.

We ask this throughWe ask this through

Our Lord Jesus Christ, Your Son,Our Lord Jesus Christ, Your Son,

Who lives and reigns with YouWho lives and reigns with Youand the Holy Spirit,and the Holy Spirit,

One God forever and ever.One God forever and ever.

Amen.Amen.


2/24

YERSINIA and

PASTEURELLA


3/24

Generalities

short, pleomorphic, gram (-) rods

exhibit bipolar staining (hairpin-like)

microaerophilic or facultative anaerobe

catalase (+), oxidase (-)

most have animals as natural host


4/24

3 Pathogenic species ofYersinia

Y pestis

Y pseudotuberculosis

Y enterocolitica


5/24

Yersinia pestis & Plaque

Plaque: an infection of wild rodents,

sometimes transmitted to man

responsible for pandemics of

black death

organism transmissible by aerosol


6/24

Morphology & Identification

gram (-) rod, exhibits bipolar staining

non motile, facultative anaerobe

optimum growth: media with blood or

tissue fluids at 30C

virulent strains: gray & viscous colonies


7/24

Antigenic Structure

all have lipopolysaccharides with endotoxicactivity

The 3 pathogenic species have antigens &toxins, that act as virulence factors

V & W antigens: produced by virulent strains plasminogenactivatingprotease, which has

coagulase & fibrinolytic activity involvedin dissemination from flea bite injection site

capsule: antiphagocytic activity phospholipase D: survival in the flea midgut Yersiniabactin: iron-scavenging siderophore


8/24

Pathology & Pathogenesis

Flea feeds on a rodent with Y pestis

organism multiply in the gut of flea

blocks its proventriculus no food

passes through flea becomeshungry flea bites ferociously

organism is regurgitated into the bite

wound (contd next slide)


9/24

Contd..

Organism phagocytosed by PMN &

macrophages killed by PMN but

multiply in the macrophages

organism reach lymphaticslymphadenopathy & hemorrhagic

inflammationnecrosis

dissemination to all organs

meningitispneumonia, pleuropericarditis


10/24

NB.

Primary pneumonic plague results from

inhalation of infective droplets with

hemorrhagic consolidation, sepsis & death


11/24

Clinical Findings

Incubation period: 2-7 days

S/S: high fever, painful lymphadenopathy,

(groin or axillae), vomiting & diarrhea

may develop with early sepsis Later: DIC hypotension, altered mental

status, renal & cardiac failure

Terminal: pneumonia & meningitis

NB. Plague should be suspected in febrile patients exposed to

rodents in known endemic areas


12/24

Laboratory Tests

specimens: blood, aspirates from LN, sputum,CSF

smears: Gram staining; for bipolar appearance,

use the ffg: Wrights, Giemsa, Waysons culture: BAP, CAP, McConkey, BHI broth biochemical reactions: catalase (+), indole-

oxidase-urease (-), nonmotile

serology: antibody titer (1:16 or greater) presumptive evidence ofY pestis infection

NB. Definite Identification of culture best by IF or by lysis byspecific Y pestis bacteriophage


13/24

Treatment

DOC: streptomycin

gentamycin

doxycycline

NB. untreated plaque has a mortality rate of about

50%; pneumonic plaque, nearly 100%


14/24

Epidemiology & Control

plaque is an infection of wild rodents,

that occurs in many parts of the world

humans can be infected by flea bites, or

by contact

commonest vector: rat flea

control of plaque: destruction of plaque-

infected animals & isolation of allpatients with suspected plaque


15/24

Y enterocolitica &Y pseudotuberculosis

gram (-) bacilli, nonlactose fermenter urease (+), oxidase (-) found in the GIT of a variety of animals,

(in which they may cause disease) transmissible to humans, producing a variety

of clinical syndrome transmission to humans: probably by

contaminated food, drink or fomites human infection: probably by ingestion of

materials contaminated with animals feces


16/24

Pathogenesis & ClinicalFindings incubation period: 4 7 days

organism multiply in the gut mucosa

(esp. ileum) inflammation & ulceration

fecalysis: WBC

S/S: fever, abdominal pain, diarrhea(watery to bloody)

diarrhea: may be due to an enterotoxin orinvasion of mucosa (contd next slide)


17/24

immunologic reaction:

arthralgia, arthritis & erythema nodosum

(those with histocompatibility antigen HLA-B27)

most cases: self-limited

rarely: pneumonia, meningitis, sepsis

Pathogenesis & Clinical Findings(contd)


18/24

Laboratory Tests

specimens: stool, blood, material from

surgical exploration

culture: cold enrichment of stool :(buffered saline, pH 7.6, 4C, 2-4 wk)

then, cultured on McConkey

serology: Agglutinating antibodies,

(however, cross reactions between otherorganism may confuse results)

NB. stained smears are not contributory


19/24

Treatment

aminoglycosides chloramphenicol tetracycline

TM-SMX piperacillin 3rd gen cephalosporins

fluoroquinolones

NB. typically resistant to ampicillin & 1st gen cephalosporins


20/24

Prevention & Control

most human infections: contact with

animals, their feces, or contaminated

materials

meat & dairy products, contaminatedfood & drink

NB. no specific preventive measures


21/24

Pasteurella

primarily animal pathogens

nonmotile, gram(-) coccobacilli, with

bipolar appearance

aerobic or facultative anaerobe

oxidase-catalase (+)


22/24

P multocida

distribution: worldwide perhaps the most common organism in

human wounds inflicted by bites fromcats & dogs

P bettyae: infections of human genital tract& of newborns

P pneumotropica: normal inhabitant of RT& gut of mice

P ureae: mixed flora in human chronicrespiratory disease or other suppurativeinfections


23/24

Clinical Findings

most common presentation: history ofanimal bite, followed within hours by anacute onset of redness, swelling & pain

regional lymphadenopathy is variable,fever often low grade sometimes: presentation is bacteremia or

chronic respiratory infection (withoutevident animal connection)

P multocida: penicillin G (DOC),tetracycline, fluoroquinolones


24/24

Oh god, Who teachesOh god, Who teachesthe hearts of the faithfulthe hearts of the faithful

by the light of the Holy Spirit:by the light of the Holy Spirit:

Grant, by the same Spirit,Grant, by the same Spirit,

That we may relish what is right,That we may relish what is right,

And ever rejoice in His consolation.And ever rejoice in His consolation.

We ask this throughWe ask this through

Our Lord Jesus Christ, Your Son,Our Lord Jesus Christ, Your Son,Who lives and reigns with YouWho lives and reigns with You

and the Holy Spirit,and the Holy Spirit,

One God forever and ever.One God forever and ever.

AmenAmen

FACULTAS MEDICINAE ET CHIRURGIAEFACULTAS MEDICINAE ET CHIRURGIAE

PRAYER AFTERPRAYER AFTER

CLASSCLASS

micro lec 17 - yersinia

Documents