52PhotoOpportunityII:Photos&QuestionstoTestYourBoardPreparationANSWERKEYJohn E. Bennett, M.D.

 

 

#1Bloodculturesofthispatientarelikelytogrowwhichofthefollowing: 

A. GramnegativecocciB. GrampositivecocciC. GramnegativebacilliD. Grampositivebacilli

Correctanswer:A

Answer:Thispatienthaspurpurafulminans,usuallyduetoNeissseriameningitidis;lessoftenotherorganisms.

#2Thispatientwithprofound,prolongedneutropeniahadtherapidonsetoffeverandthesepainfulskinlesions.Themostlikelytesttorevealtheetiologyis: 

A. BloodcultureB. PunchbiopsyC. SerumgalactomannanD. BloodPCR

Answer:B

Rationale:Thisisecthymagangrenosa,usuallyduetoamould,PseudomonasaeruginosaoroccasionallyanotherGramnegativebacillus.Bloodculturesarerarelypositivewithaspergillosisormucormycosisbutmaybepositivewithfusariosisorbacteria.Immediatepunchbiopsywithculture,GramstainandimpressionsmearusingCalcofluorstainforhyphaecanbedoneinhourswhilewaitingforbloodcultureresults.

#3Extensionofhispatient’ssphenoidsinusitisislikelytoresultinwhichphysicalfinding

A. MonocularblindnessB. Facialnumbness C. DysconjugategazeD. Bell’spalsy

Answer:C

Rationale:Thispatienthasextensionintothecavernoussinus,ascanbeseenfromthecarotidarteryintheupperportionofthesinus.Cranialnerves3,4,and6traversethecavernoussinusandleadtoearlyoculomotorpalsy.Theoptic,fifthandseventhnervesdonottraversethecavernoussinussomonocularblindess,facialnumbnessandBell’spalsyarenotseen.

#4Thisyounglady’shottubrashwasmostlikelyduetowhichofthefollowingorganisms:

A. AeromonasB. Pseudomonas C. StenotrophomonasD. Staphylococcusaureus

Answer:B

Rationale:Pseudomonascancauseafollicularrashinexposedskinafterhottubbathing,oftenlocalizedundertheswimtrunks.Staphylococcalfolliculitisismorepurulentandusuallyinareaswithhair,particularlywithshaving,notbathing.Theotherorganismsdonotcausefolliculitis.

   

#5Thissofttissuegasinapatientwithneutropeniaandadenocarcinomaofthecolonismostlikelyduetowhichorganism:

A. Clostridiumsepticum B. FusobacteriumnecrophorumC. BacteroidesfragilisD. Eikenellacorrodens

Answer:A

Rationale:Clostridiumsepticum.Gasformationisacommondevelopmentinclostridialmyonecrosisandisnotseenwiththeotherbacillilisted.C.septicumisnotableforcausingbacillemiaandmetastaticlesionsinimmunosuppressedpatients.

 

 

#6This31‐year‐oldwomanwithprolongedneutropeniadevelopedthesuddenonsetoffever,shock,andseverepainandrashinherleg,extendingover24hours.Softtissuefilmshowednogas.Themostlikelyorganismis:

A. Staphylococcusaureus B. ClostridumperfringensC. StreptococcuspyogenesD. Aspergillusfumigatus

Answer:C

Rationale:Streptococcuspyogenes.Necrotizingfasciitisshouldbesuspectedandurgentsurgicalconsultationobtained.Clostridialmyonecrosismaynotshowgasearlyinthecoursebutislesslikelyintheabsenceofaportalofentry.NeitherS.aureusorAspergilluswouldprogressthisrapidly.

   

 

#7Thislungbiopsyshowscellsthatstainpinkish‐redwithMayer’smucicarminestain.

Themostlikelyorganismsis:

A. BlastomycesdermatitidisB. HistoplasmacapsulatumC. ParacoccidioidesbrasiliensisD. Cryptococcusneoformans

Answer:D

Rationale:MucicarminestainishelpfulinconfirmingthatayeastintissueisaCryptococcus,thoughnotallcryptococcalcellsonapathologyslidewillstainclearlypositive.

 

 

#8This40‐year‐olddentistpresentedwithpainandswellinginhiselbowofthreedaysduration.Hehadfullrangeofmotionintheelbowdespitediscomfortonmotion.Hewasafebfrile.Thisismostlikely:

A. OlecranonbursitisB. Cellulitis C. SepticarthritisD. Tophaceousgout

Answer:A

Rationale:Olecranonbursitis,usuallyduetoStaphylococcusaureus,isdistinguishedfromsepticarthritisbynotrestrictingrangeofmotion.Localizationtotheolecranonbursaareaisunlikelyforcellulitisorgout.

   

#9Ifthispatient’sbloodculturewerepositive,whichofthefollowingwouldbemostlikely?

A. StreptococcusanginosusB. EnterococcusfaecalisC. StreptococcusagalactiaeD. Staphylococcusaureus

Correctanswer:C

Rationale:S.aglactiae(StreptococcusgroupB)ErysipiliscanbeduetoStreptococcusgroupsA,B,C,orGbutnotenterococciorS.anginosus.CellulitiswithbacteremiainthislocationwouldbeunlikelyduetoStaphaureus.

#10Thispreviouslyhealthy35yearoldMarylandwomanhadthesuddenonsetoffever,convulsionsandconfusionafterleavingherofficeinJuly.Themostlikelyorganismis:

A. WestNilevirusB. EasternequinevirusC. HerpessimplexvirusD. Varicellazostervirus

Answer:C

Rationale:Alesioninthemedialportionofthetemporallobeisseenshortlyafteronsetinnearlyallcasesofherpessimplexencephalitisandnotintheotherentities.

#11Findinganacidfastbacillusinanasalsmearismostconsistentwith. 

A. rhinoscleromaB. rhinosporidiosisC. LeishmaniasisD. lepromatousleprosy

Answer:D

Rationale:Patientswithlepromatousleprosyoftenhaveacidfastbacilliintheirnasalsmear.Inendemiccountriesnasalmucosaalongwithskinsnipsfromselectedsitesaresampledtoclassifyleprosyaslepromatousandtodeterminethebacillaryload.Leishmania,rhinoscleromaandrhinosporidiosisarenotacidfast.

#12Thisindolentskinlesiononthehandandforearmismostconsistentwithinfectionwithwhichofthesemycobacteria:

A. M.chelonaeB. MmarinumC. M.abscessusD. Mulcerans

Answer:B

Rationale:M.marinumistheonlyMycobaacterialspecieswithlymphaticspread.

#13This25‐year‐oldU.S.collegestudentfromIndiapresentedwithprogressivethoracicbackpainofthreeweeksduration.Themostlikelyportalofentryis

A. lungB. gastrointestinaltractC. skinD. paranasalsinus

Answer:A

Rationale:Vertebralosteomyelitisinthispatientismorelikelytuberculosis(lung)thanbrucellosisoractinomycosis(GItract).Nosourceofstaphylococcalsepsis,suchasinjectiondruguse,wasincludedinthequestion.

#14Patient’swiththisconditionaremostpronetowhichoftheseseriouscomplications

A. hemoptysisB. brainabscessC. spreadtocontiguousboneD. spreadwithinthelung

Answer:A

Rationale:Massivehemoptysisisaninfrequentbutpotentiallylethalcomplicationoffungusballofthelung.Spreadofthefungus,usuallyAsperglllus,beyondthecavityisextremelyrare.

#15Thisotherwisehealthypatientwithachroniclegulcerismostlikelytohave:

A. Commonvariableimmunoglobulindeficiency

B. Lupuserythematosus

C. HepatitisC

D. Ulcerativecolitis

Answer:D

Rationale:Thisisatypicallesionofpyodermagangrenosa.Themostcommonunderlyingdiseaseisulcerativecolitisandmayprecedetheonsetofboweldisease.

 

#16

A27‐year‐oldAfrican‐AmericanfemaleofficeworkerfromWashington,D.C..presentedwith3weeksofincreasinglyseveremidabdominalcrampingnonradiatingpain,associatedwithnauseaandoccasionalemesisthepasttwodays.Nofeverhadbeennoted.Shehadbeendiagnosed2monthsearlierwithHIV,withaviralloadof861,000andaCD4of8.Shewasbegunontrimethoprim‐sulfamethoxazoleprophyhlaxis,andemtricitabine/tenofovir,darunavirandritonavirforherHIV,allofwhichshestatedweretakenregularly.Onexamshewasafebrile,hadanobese,distendedabdomenwithslighttenderness,noreboundandgoodbowelsounds.Laboratoryworkwasunremarkableexceptthatherviralloadhadfallento54,000andherCD4hadrisento72.TheCTisshown.Surgicalconsulationfeltlaparotomywasunnecessaryandpercutaneousneedleaspirationwasdeclinedbyradiology.BasedontheCTscanandclinicalpresentation,whichofthefollowingempiricinterventionswouldbethebestoptioninthispatientgiventheinabilitytoobtainatissuesample?

A. Empiricaltherapyformycobacteriumaviumcomplex(MAC)B. EmpiricaltherapyfortuberculosisC. EmpiricaltherapyforhistoplasmosisD. StopalltheantiretroviralsE. Changedarunavirtolopinavir

Answer:A

Rationale:

TheclinicalpresentationismostconsistentwithimmunereconstitutionsyndromefromMycobacteriumaviummesentericlymphadenitis.SomecliniciansmightopttowaittoseeifthisresolveswithouttherapyforMAC,butsinceshehasneverbeentreatedforMAC,thebestoptionforthoselistedwouldbeA.TheCTshowsnecroticnodessurroundingthemesentericartery.Neithertuberculosisnorhistoplasmosispresentwithsuchflagrantmesentericlymphadenitis,thoughabiopsyisindicatedtoconfirmthediagnosis.Stoppingantiretroviraltherapyforimmunereconstitutionsyndrome(IRIS)isnotrecommended.ThereisnoreasontochangedarunavirtolopinavirOfcourse,avarietyofculturesandserologiesshouldbeperformedtoattempttoidentifythecausativeorganism,butinthiscasenonearelikelytobepositive.  

   

#17A19‐year‐oldcollegestudentpresentedtothestudenthealthservicewithasorethroatandfeverofthreedays’duration.Hehadnotpreviouslysoughtmedicalcarebecauseitwas“deadweek,"studyingforfinalexaminations.Today,therashshowninthephotoappeared.Itwasnonpruritic.Exceptforatemperatureof101°F,sometonsillarexudatesbilaterallyandtherash,hisexaminationwasnormal.Arapidstreptestwasnegativesoathroatculturewasobtainedandtreatmentwithheld.Thenextdaytheculturewasreportedashavingnobeta‐hemolyticstreptococci.Themostlikelybacterialcausewouldbewhichofthefollowing:

A. GramnegativecoccusB. GrampositivebacillusC. GramnegativebacillusD. Weaklyacidfastbacillus

Answer:B

Rationale:Arcanobacteriumhaemolyticumcausesascarletfever‐likepictureinyoungpersonsbutwithoutpoststreptococcalsequelae.Illnessistypicallymildsothatefficacyofmacrolidetherapy,whichshouldbeeffective,isdifficulttodocument.Growthofthisdiphtheroid‐likeorganismisalittleslowerthanStreptococcuspyogenes,oftennotbeingrecognizeduntil48to72hoursafterinoculation.ThenegativethroatcultureforStreptococcuspyogenesofthispatientwithpharyngitisisagainstthediagnosisofscarletfever.Therashisalsoatypical,withno“strawberrytongue”and“circumoralpallor”suggestiveofscarletfever.

#18

ThistwochestCTstakenaweekapart,werefromapatientwithallogeneicbonemarrowtransplantation,acutegraftversushostdiseaseandfevernotrespondingtoantimicrobialagents.  

 

 

 

 

 

 

 

 

 

A. DirtinthepottedplantinhisroomB. HisoralfloraC. HospitalfoodD. Intravenouscatheter

Answer:A

Rationale:

Aseverelyimmunosuppressedpatientwhodevelopslocalizedpulmonaryinfiltratewithadensecenterandnoairbronchogramshouldbesuspectedtohaveaspergillosisor,lesscommonly,mucormycosis.Ahazyborder,calleda“halosign”isparticularlysuggestive.Cavitationofthelesion,oftenasthepatient’simmunosuppressionlessens,isalsotypical.Thesemoldliveindecayingvegetationandsoil,enteringthebodybyinhalationintothelungorparanasalsinu,oroccasionallycauseskinlesionsatthesiteofminortrauma.

#19Thesepainfulrecurrentlipandmouthlesionsarefromawomanwithpriorpainfullabialulcers,arthritisofthekneeanddecreasedvisioninoneeye.Themostlikelydiagnosisis:

A. Reiter’ssyndromeB. AntiiphospholipidsyndromeC. Systemiclupuserythematosus(SLE)D. Behcet’s

Answer:D

Rationale:Recurrentpainfululcersinthemouth,lipsorgenitaliashouldsuggestBehcet’ssyndrome,aclinicalentitythatcanincludeskinlesions,iritisoruveitis,andpathergy,whichisaninflammatoryresponsetomildskintrauma.Reiter’ssyndromeoracutereactivearthritis,isacombinationofrecurrentepisodesofarthritis,conjunctivitisandurethritis.Othermanifestationsincludekeratodermablennorrhagica,whicharehardnodulesonthesolesorpalms,uveitisandpainlessulcersonthetipofthepenis.Antiphospholipidsyndromeischaracterizedbyvenousthrombosesinunusualsitesbutnomucosallesions.SLEmaycausearthralgiasbutnotrecurrentoralulcers.

#20

This35‐year‐oldPeruvianwomanwithchronicmyelogenousleukemiainblastcrisiswasadmittedforallogeneichematopoieticstemcelltransplantationfromhersister.Onadmission,thisextensivepainfulrashwasfoundontheglutealareaofbothbuttocks.Shecomplainedthattheareahadbeenpainfulforseveraldays.Shewasafebrilebutweakandmarkedlygranulocytopenicfrompriorchemotherapy.Themostlikelydiagnosisiswhichofthefollowing:

A. HerpeszosterB. HerpessimplexC. EcthymagangrenosaD. AspergillosisE. Sweet’ssyndrome

Answer:B

Rationale:ThislesionisduetoHerpessimplexvirus.Herpessimplex,unlikeherpeszoster,canspreadbylocalinoculationandpresent,asinthiscase,onbothsidesofthemidline.Skinthatismoist,suchasintertriginousareas,areparticularlysusceptibletoinoculation.Thispatientwasfebrile,sweating,andlyinglongperiodsonherback.Intheprocesssheinoculatedherpessimplexfromaninapparentlesion,probablygenital,intotheskinofherback.Thislesiondoesnotresembleecthymagangrenosa,aninfectionusuallyduetohematogenousdisseminationtooneorseveralsitesofPseudomonasaeruginosa,Aspergillusoranagentofmucormycosis.Theselesionsareinitiallyred,thenpurpleandfinallynecroticinthecenterfrominvasionofdermalbloodvessels.Ecthymagangrenosacanbehematogenousorlocallyinoculatedingranulocytopenicpatients.Withhematogenouslesionsthepatientsarecriticallyill.Withlocalinoculation,thepatientisoftennotseptic.Sweetssyndromewouldnotlikelybethisextensive,wouldnotlikelybutonthebuttock,andwouldnotcharacteristicallyoccurinaneutropenicpatient.Sweet’ssyndromeischaracterizedbyabruptonset,characteristicpathology,andmaybeassociatedwithfeverandleukocystosis.Thelesionstendtobesmallerandpainful.   

   

#21Thisisthepruriticrashonthearmofan18‐year‐oldcounciloratasummercampinnorthernMichigan.Heandanotherfellowcampcouncillordevelopedthisrashafterswimminginthelakeatthecampafewdayspreviously.Theyoungcamperswhoalsowentswimmingwithhimdidnotdeveloptherash.Thiswastheirfirstyearatcampbutthetwocouncilorshadbothattendedcamplastyear.Whichofthefollowingorganismsisthemostlikelycauseofthisrash?

A. LeptospiraspeciesB. PseudomonasspeciesC. BorreliaspeciesD. Schistosomespecies

Answer:D

Rationale:Thisisswimmer’sitch,duetoswimminginwatercontaminatedwithavianschistosomes.Thecercariaburrowintotheskinanddie.Personspreviouslyexposedhaveanintenseallergicreactiontothetinyschistosomes.Inthecasecitedabove,thecouncilorsfromtheprioryearweresensitizedfromswimmingincontaminatedwaterthepriorsummer.Humansarenotthepreferredhostfortheseparasites,andthusthecercariacannotmigratetotheliverorgenitourinarytractaswithSchistosomamansoni,hematobium,japonicumetc.SwimmersitchcanbeseeninmanyareasoftheUS.Nospecifictreatmentisindicated.Antihistaminesandtopicalsteroidsareuseful.Symptomsabateafter1‐2weeks.Superinfectionsoftheabradedskinwithbacteriacanoccur.

#22A38‐year‐oldmanwhorefusedtherapyforhisfaradvancedHIVwasadmittedforinanition,weakness,profoundweightlossandchronicdiarrhea.Hisintestinalbiopsyshowswhichofthefollowingorganisms:

A. CyclosporacayetanensisB. MicrosporidiumafricanusC. EnterocytozoonbieneusiD. CryptosporidiumparvumE. Rhodococcusequi

Answer:C

Rationale:ThetinyorganismswithinthecytoplasmareinthewronglocationandofthewrongsizeforCyclosporaorCryptosporidiumbutaretheagentsofmicrosporidiosis,aninfectioncausedbyspeciesofEnterocytozoonandEncephalitozoon.Thereare1200speciesofmicrosporidia,allobligateintracellularparasitesofvertebratesandinvertebrates.ButnoneofthegenusMicrosporidiumareknowntoinfecthumans,despitethename,microsporidiosis.PatientswithAIDSareuniquelysusceptibletomicrosporidioisiswithE.bieneusibeingthemostcommonagentandpresentingasdiarrheaandweightloss.ThereisnoknowneffectivetherapyofE.bieneusiinfection,otherthanrestoringimmunefunctionwithhighlyactiveantiretroviraltherapy.

#23This22‐year‐oldfemalefromAtlantapresentedbecauseoffeverandpainherrightlowerlegoftwodaysduration.Therightachillestendonareawassopainfulshecouldnotbearweightontherightleg.Shehadbeenpreviouslyhealthy,workingasanursesaid,wassingle,andrecentlyhadacquiredanewsexualpartner.Shehadhadlowgradeabdominalpainandloosestoolsaweekpriortoonset,whichsheattributedtoeatingfoodatachurchpicnic.Onexam,shehadatemperatureof102°Fandared,tenderareaovertherightachillestendonarea,withmarkedpainonankleflexion.Therewasared,slightlytenderlesionovertheleftpretibialarea.Amongthefollowingpossibilities,whichisthemostlikelycauseofherillness?

A. AcutereactivearthritisB. NeisseriainfectionC. ChlamydiainfectionD. YersiniainfectionE. Psoriasis

Answer:B

Rationale:Thepatientislikelytohavedisseminatedgonococcalinfectioncausinghertendonitis.Gonorrheaistheonlyoptionlistedhereassociatedwithtendonitis,althoughtheotherscouldbeassociatedwitharthritis.Patientsusuallydonothaveapparentgenitourinarymanifestations,anddevelopsomecombinationofskinlesions,polyrthralgias,andpolyarthritisthatisasymmetricandinvolvessmallorlargejoints.Theclassicpatientisawomanwhoispregnantormenstruating.Reiter’ssyndrome,nowmorecommonlycalledacutereactivearthritis,wouldbelesslikelyassociatedwithtendonitis.YersiniaandChlamydiadonotcausetendonitis.

#24An18‐year‐oldmalehadtheacuteonsetofsorethroat,followedintwodaysbyhighfever.Onpresentationintheemergencyroomhewasacutelyill,withatemperatureof105°F.Chestx‐ray,followedbytheCTshownhere,showedanoduleintheleftlowerlungfield.SwellingandtendernessintherightanteriorcervicaltriangleledtotheCTwithIVcontrastshownhere.Bloodcultureswerelikelytorevealwhichofthefollowing:

A. AerobicGrampositiverodB. AerobicGramnegativerodC. AnaerobicGrampositiverodD. AnaerobicGramnegativerodE. Endemicmycosis

Answer:D

Rationale:ThispatienthasLemierre’sdisease,asshownbytheclotpartiallyobstructingtheinternaljugularveinandlungnoduleofthesepticembolus.Lemierre’sbeginswithasorethroatwithhighfever.Infectionextendsfromthetonsillarareatotheinternaljugularvein,causingsepticphlebitis,bacteremiaandsepticembolitothelung,sometimesfollowedbyempyema.TheorganismisalmostalwaysaFusobacteriumspecies,allanaerobicGramnegativerods,usuallyFusobacteriumnecrophorum.MostFusobacteriumisolatesaresusceptibletobeta‐lactams,metronidazoleandclindamycin.Notallpatientshaveswellingintheanteriorcervicaltriangle,asdidthispatient,andissomethepharyngitishasbeguntorespondtoantimicrobialtherapywhilethesepticphlebitisisprogressing.Peritonsillarabscessesmaybeseenonimagingofsomepatients.

#25This55‐year‐oldwomanfromHonoluluhadbeenreceivingprednisoneindosesof20‐60mgforuveitiswhenshedevelopedaseriesofindolentredlesionsonherrightarm,leftarmandrightshin.Theywerenotpainful,occasionallydrainedadropofserosanguineousfluidandenlargedoverthecourseofseveralweeks.Shewasafebrileandhadanormalphysicalexamexceptforuveitisandthelesions.HerchestCTscanisnormal.Therewasnoresponsetotwoweeksofcephalexin.Whichoneofthefollowingdiagnoseswouldbethemostlikely?

A. SporotrichosisB. ErythemanodosumC. LeprosyD. NontuberculousMycobacteriumE. Nocardiosis

Answer:D

Rationale:Sincetheselesionsaredisseminated(rightandleftarms,rightshin)thisisadifferentsyndromethansomeonewhodevelopssporotrichoidlesionsononearmorleg.Mycobacteriumchelonaecancauselesionsonmultipleskinsiteswiththeabsenceofdeeplesionsorsystemicsymptoms.Theportalofentryisusuallyunknown.

Sporotrichosiscancausehematogenouslesionsfromapulmonaryportalinimmunosuppressedpatientsbutskinlesionsarerarelytheonlysign.Erythemanodosumoversomanysitesisuncommon.Leprosylesionsarenotthislocalizedorpapulonodular

#26This67‐year‐oldmanwasbroughttothehospitalbythepoliceinWashingtonDCinbecausehewassleepingonagrateinbittercoldweatherand,whenaskedtomovealongbythepolice,beganmutteringincoherently.Intheemergencyroomhewascombativeandhadtoberestrained.Hewasadmittedforobservationandhadnumerousskinlesionssuchastheoneshown.

Whichofthelistedtestsismostlikelytobeinformative?

A. WetmountofskinscrapingB. FungalcultureofskinscrapingC. AcidfastsmearofskinscrapingD. SerumVDRLE. HIVELISA

Correctanswer:A

Rationale:Thecrusted,extensiveskinlesionsaretypicalofNorwegianscabies,aconditionusuallyfoundinimmunosuppressedpatients,raisingthepossibilitythatthismanhasAIDS.Thediagnosisisbestmadebywetmountscraping.TheSarcoptesscabieiandtheirfecesareabundantinthelesions.AlthoughthismanmayhaveHIVinfection,thiswouldnotexplainthelesions.Skinlesionsofsecondarysyphilis.MycobacteriummarinumandMycobacteriumchelonaeareneverhyperkeratotic,likethelesionsshown.

 

#27

A51‐year‐oldPanamanianwomen,livingintheUnitedStatesfor30years,returnedtoUnitedStatesfromvisitingfamilyinaresidentialareanearPanamaCityfortwoweeks.Ontheseconddayhome,shehadtheonsetoffever,headache,muscleache,andretrobulbarpain.ShehadsomenauseabutnoGidiarrheaorconstipation.Thesymptomspersisted,butshedidnotseekmedicalattentionuntilthethirddayofillness,whenapetecchial,nonpruritisrashappearedonherarmsandupperchest.ThehomeshestayedatinPanamawasinthecity,hadnopets.Childrenandadultsinthefamilywerehealthy.Examinationwasnegativeexceptforfeverof102F,rashandtwotenderoccipitallymphnodes.Nonuchalrigidity.LabsrevealedaWBC0f1.6withanormaldifferentialandnoatypicallymphs,platelets168,000,NormalbloodchemistriesandchestxrayThemostlikelysourceofinfectionis:

A. FoodB. MosquitoC. FleasD. AnotherhumanE. Animalurine

Correctanswer:B

Rationale:Thisisthetypicalrashofdengue,whichappearsafterseveraldaysoffever,myalgiaandheadache.Thrombocytopeniaisoftenpresentinthesickerpatientsandcanbeofdiagnosticaid,butwasnotpresentinthislady.Leukopeniaiscommonandwaspresenthere.Dengueismoreofanurbandiseasethanmalaria,duetotheabilityoftheAedesaegyptimosquitotobreedinsmallurbanpoolsofwater,asinoldautotires,nearhumanhabitationandtobiteinthedaytime,particularlyintheearlymorningandlateafternoon.Theincubationperiodisusually4‐7daysbutcanbeupto14days.Thispatientwasnotexposedtoanimalurineandtherashandleukopeniaisagainstthediagnosisofleptospirosis.RatfleascanspreadmurinetyphusbutthatinfectionislesscommoninPanamaandtherashisusuallymoresubtle.Therashoftyphoidfromcontaminatedfood,calledrosespots,ismuchlessextensivethanthediffuserashshownhere.

#28A23‐year‐oldnurse,8weekspregnant,soughtadvicefromherobstetrician.Forthepasttwoweeksshehasbeentakingcareofahospitalizedchildwithsicklecelldiseaseandaplasticcrisis.Forthepastfivedaysshehashadlowgradefever,headache,themildlypruriticrashshownhereandachingjointswithstiffnessinherhandsandfeet.Shehadalltheusualchildhoodvaccinations,wastakingnomedications,livedalonewithherhusband,andhadnopets.Theobjectofconcernforherunborninfantwouldbewhichofthefollowing:

A. DeafnessB. HydropsfetalisC. ThrombocytopeniaD. CongenitalheartdiseaseE. Mentalretardation

Answer:B

Rationale:Patientswithchronichemolyticdiseases,suchassicklecelldisease,aresusceptibletochronicParvovirusB19infections(alsocalledErythrovirusB19)andcanshedvirusintheirsecretions,presentingriskofinfectiontotheircontacts.Althoughmanyadultshaveserologicevidenceofinfection,previouslyuninfectedpregnantwomenmaytransmitthevirustothefetus.Arrestoferythrocyteproductionleadstosevereanemiaandcongestiveheartfailureinthefetus.Intrauterinetransfusionmaysalvagethepregnancybutfetallossisaseriousrisk.Theotherfetalabnormalitiesarecharacteristicofcongenitalrubella(deafnessandcongenitalheartdisease),toxoplasmosis(hydrocephalus,retinitis,disseminateddisease)orcytomegalovirusinfection(disseminateddisease)

#29Thissofttissuefilmofaperson'slowerextremityismostconsistentwithwhichofthefollowing?

A. StaphylococcalpyomyositisB. StreptococcuspyogenesnecrotizingfasciitisC. ClostridialmyonecrosisD. Pyomyositis

Answer:C

Rationale:Gasinmultiplefascialplanesishighlysuggestiveofclostridialmyonecrosisandwouldnotbeexpectedintheotherentitieslisted.Notethatpyomyositisisaprimarymuscleinfection,usuallycausedbyStaphylococcusaureus,andmorecommoninthetropics.However,thiscanoccurafterpenetratinginjury,orvascularinsufficiencybutwouldnotbeassociatedwithsofttissuegas.

#30

Thisskilesionistypicalofwhichentity:

A. PurpurafulminansB. ImpetigoC. PyodermagangrenosumD. Ecthymagangrenosum

Answer:D

Rationale:Thesharplydelimintedborder,centralnecrosisandpaleouterborderistypicalofecthymagangrenosum.

 

#31This21‐year‐oldAfricanAmericanmalecollegestudentinTucson,Arizonawasseenbecauseoflowgradefever,malaiseandscalplesionsprogressingoverthepast3weeks.HehadvisitedNogales,Mexicowithsomeofhisfraternitybrotherssixmonthsearlierandhadsexwithaprostitute.Aboutamonthago,hewasdrunkataparty,fellintoapondandrequiredresuscitation.Askinbiopsyisshownbelow.

Themostlikelyetiologicagentisfoundinwhichofthefollowinglocations:

A. PondscumB. DirtC. GenitallesionsD. BatdroppingsE. Pigeondroppings

Answer:B

Rationale:

Thespheruleindicatesthediagnosisofcoccidioidomycosis.AfricanAmericansareamuchhigherriskofdisseminationthanCaucasians.Sitesofdisseminationprominentlyincludebone,joint,softtissue,meningesandskin,thoughotherorgansmaybeaffected.Thesourceofinfectionisinhalationfromthesoil.CoccidioidessporesareextremelyresistanttodesiccationandheatofsummerintheSouthwestUnitedStates.Arizonahasthehighestattackrateofcoccidioidomycosis,withCaliforniacominginsecond.Tucsonisinahighlyendemicarea.

#32

This40‐year‐oldcrabfishermanworkingintheChesapeakeBaywaterscameinwithlowgradefeverandapainfulrashonhishandofthreedays'duration.Hecuthishandseveraldaysagoonacrabspine.Theprobableorganismiswhichofthefollowing:

A. CurvedgramnegativerodB. Seagull‐shapedgramnegativerodC. GrampositivecoccusD. Grampositivebacillus

Answer:D

Rationale:Erysipelothrixrhusiopathiaecauses“erysipeloid”lesionsfollowingscratchesinbrackishwater.Bacteremiaisuncommon,butwhenitoccurs,isusuallyaccompaniedbyendocarditis.Erysipelothrixrhusiopathiaeisapleomorphic,gram‐positivebacilluscapableofcausingself‐limitedsofttissueinfectionorserioussystemicinfection.E.rhusiopathiaeiswidespreadinnature,occurringindomesticandmarineanimalsincludingcattle,chickens,crabs,andfish.Crabpickersareclassic,butswinefarmersmaybemorecommon.Infectioninhumansisusuallyduetooccupationalexposure.Thus,slaughterhouseworkers,butchers,fishermen,farmers,andveterinariansareatrisk.Thetypicalmanifestationsarelocalizedordiffuseskinlesions,orbacteremiawithorwithoutendocarditis

 

#33This69‐year‐oldmalealcoholicwentintoshockaftereatingrawoysters.Hemostlikelywasinfectedwithwhichorganismfromamongthefollowing:

A. StreptococcusB. StaphylococcusC. VibrioD. Clostridium

Answer:C

Rationale:Vibriospecies,usuallyvulnificus,cancausetheserapidlyspreadinghemorrhagiclesionsafteringestionofcontaminatedpoorlycookedshellfish.

 

#34

ThisHaitianfarmerwasvisitinghisfamilyintheUnitedStateswhenhesoughthelpforthispainlessfirmfootswellingoftenyearsduration.Oneslideshowsthefootandtheotherabiopsyofthelesion.

Themostlikelyorganismiswhichofthefollowing:

A. PseudomonasaeruginosaB. BurkholderiapseudomalleiC. StaphylococcusaureusD. MadurellamycetomatisE. Aspergillusfumigatus

Answer:D

Rationale:Chronicsubcutaneousfirmlyinduratedswellingsoveranextremityshouldsuggestthepossibilityofmycetoma,particularlyiftherearedrainingsinuses.Infectionfollowsintroductionofdirtorvegetationintotheskinbyminortraumaandprogressesovermanyyears.Underlyingbonemaybeinvaded,allowingconfusionwithchronicosteomyelitis,thoughthefirmswellingisunlikeosteomyelitis.Thereisnofever,leukocytosisorevenmuchpainwithmyetoma.Thisinfectioniscausedbyavarietyoffungiorhigherbacteria,allofwhichformvisiblecolonies,calledgrains,inthedrainingsinuses.Drainageispurulentbutbacterialsuperinfectionisrare.

#35

Thisparasite,shownasanegg,wasacquiredfromwhichsource?

A. FreshhumanstoolB. IngestingcontaminatedearthC. EatingpoorlycookedporkD. Eatingpoorlycookedbeef

Answer:B

Rationale:Ascarislumbricoideseggsneedtomatureintheearthbeforetheyareinfectious.Infectionstypicallyareacquiredwhentheeggisshedintotheenvironmentinhumanstool,andanotherhumanaccidentallyingeststhematureeggfromdirtorrawproduce,whichthenmatureintolarvaewhichpenetratethegutwall,circulatetothelung,ascendthetracheobroncialtree,isswallowedandmaturesintheGItractasworms.Humanmaybesymptomaticduringmigrationthroughthelungs(eosinophilicpneumonia),butthewormsintheGItractusuallyproducefewsymptomsinadults,althoughoccasionalcasesofmildabdominaldiscomfortorappendicitisoccur.Intestinalblockadeoccursprimarilyinchildren.Iftheascarisingestedisfromadogorcat,theorganismpenetratestheintestineafteringestion,andentersthebloodstream,butcannotcompleteitslifecycleintheorganwhereitlodgesandproducesviscerallarvamigransduetoinflammationinthetargetorgan.

 

#36Whatisthemostlikelysourceoftheorganismseeninthisintestinalbiopsy?

A. WaterB. HamburgerC. RaspberriesD. HumanhandsE. Unrefrigeratedprocessedmeat

Answer:A

Rationale:CryptosporidiosisismostlycommonlyacquiredintheUnitedStatesthroughrecreationalwater(waterparks,communityswimmingpools)ordrinkingwater.Theparasites,usuallyCryptosporidiumparvumorCryptosporidiumhominis,undergotheirlifecycleinthesuperficialcytoplasmofintestinalepithelialcells.Thephotomicrographshowsseveraloocysts.Onceexcretedinthefeces,onlyafewoocystsaresufficienttoinfectanotherhuman.Thelowinoculumandprolongedviabilityallowswatertobetheusualvehicleoftransmission,notpersontopersonspread.Inhalationinfectionisunknownandfoodtransmissionappearstobeuncommon.Thisparasitecanbetransmittedindaycarefromchildrens’fecestodaycareproviderhandsandsubsequentingestion.

 

#37ThisMRIcamefroma66‐year‐oldmaletakinghydroxycholoroquineandsteroidsforrheumatoidarthritisfor5yearsandwhohadathreemonthhistoryprogressiverightsidedweaknessandaonemonthhistoryofprogressiveaphasis.Hewasafebrile.

Themostlikelycauseamongthefollowingis:

A. HerpesvirusB. EnterovirusC. PolyomavirusD. LymphomaE. Toxoplasmosis

Correctanswer:C

Rationale:Progressivemultifocalleukoencephalopathyisaslowlyprogressingdiseaseofimmunosuppressedpatients,resemblingmultiplesclerosisonbrainMRIbecausethemajorityofthelesionsareinthewhitematteranddon’tenhanceonMRIorCTwithcontrast.LesionsonMRIarewhite(dense)onT2imaging.JC,apolyomavirusthatcausesPML,canbedetectedintheCSFofmanyPMLpatientsbyPCR.PMLhasalsobeenreportedinpatientstreatedwithHIVandefalizumab,belatacept,fludarabine,infliximab,rituximab,mycophenolate,andglucocorticoids.Manysuchpatientshadanunderlyinghematologicmalignancyorcollagenvasculardisease.Thecurrentpatientwasonlongtermcorticosteroids.Herpessimplexandenterovirusescancausesacuteencephalitisormeningitisbutnotwiththisinsidiousprogressionandafebrilecourse.ToxoplasmalesionsareenhancingonMRI,notconfinedtowhitematter,favorthebasalgangliaandarenotsoindolentasinthiscase.

#38This16‐year‐oldNavajochildwasbroughttotheFourCornersHospitalinArizonabecauseofhighfeverandthelesionsshown.Helooksquiteill.Hismotherthoughthemighthavebeenbittenbyaratwhilehewassleeping,becauseheawokecryingofpainintheabdominallesionandhadseemedtobeplayingnormallythedaybefore.Shehadseenadeadratinthegarageafewdaysprior.Onexam,hehadatempof40Candthelesionsseen.Boththelesionandtheaxillaryareawasverytender.Gramstainoftheskinlesionfoundnoorganisms.Themostlikelypathogeniswhichofthefollowing:

A. StreptobaccilusmoniliformisB. SpirillumminusC. YersiniapestisD. EikenellacorrodensE. Pasteurellamultocida

Answer:C

Rationale:Highfever,alocallesionandatenderswollenlymphnode(bubo)withprostrationsuggestsplague,tularemiaorastaphylococcalabscess,thelattertwonotbeingonthelistabove.Staphylococcalfuruncleswouldhavebeenatthesiteofminortraumaandmoreindolent.EikenellaandPasteurellamultocidatypicallydonotgiveabubo,thoughtheymaycausesepsisfromadogorcatbite.SpirillumminusisararediseasefromratbitesinJapan.ThisisnotseenintheUS.Streptobaccilusalsocausesratbitefever,withoutabubobutoftenwithrashandarthritis.Plagueisimportanttodiagnosebecausethebestdrugisgentamicin,notsomethingtypicallyusedforskinandlymphaticinfection.Thischildpresumablywasbittenontheabdomenbyafleafromarat,developedtheabdominallesion,andthenthebubo.

 

#39 

 

Theprobablesourceofthisinfectioniswhichofthefollowing?

A. FemaleanophelesmosquitoB. MaleanophelesmosquitoC. AdeertickD. Adogtick

Answer:C

Rationale:TheorganismsareBabesiamicroti,ahemoprotozoonofrodents,acquiredbyhumansfrombitesofdeerticks.BabesiahaveadifferentdevelopmentalformthanPlasmodiumfalciparum,resemblinga“maltesecross”whicharefourdotsinacluster.(Seearrowinphoto).Infectionisoftenmildbutasplenicpatientsmayhavesevereandevenfatalinfections.Thisdistinctionbasedonmorphologycanbedifficult,butthis“maltesecross”istypicalenoughtobetestable.

 

#40

A36‐year‐oldfemalewhowas2yearspostcadavericrenaltransplantationforrenalfailureduetochronicglomerulonephritispresentedwithfeveroffivedaysduration.Shehadsomenauseabutnourinary,respiratoryorabdominalsymptoms.Shehadpresentedtoanoutsidehospitalthreedayspreviouslywhereachestxray,urinalysisandbloodculturehadbeennegative.Shewasgivenlevaquinbutremainedfebrilewithmalaise.

Currentmedicationsincludedmycophenylate,sirolimusandprednisone.Shehadahistoryofhiveswithcephalexin,vancomycinanderythromycin.

Examinationfoundafeverof39.2C.grade1systolicejectionmurmurovertheleftsternalborder,andanontendertransplantedkidneyintherightlowerquadrant.Renalultrasoundofthetransplantedkidneywasnormal.Urineculturegrew10^4‐10^5E.faecalis,susceptibletoampicillin.Urinalysisfound10WBC/ul,nitrateandproteinnegative.WBCwas10,200.AbdominalCTwithcontrastshowedalobeofthekidneywhichdidnotperfusewellwithcontrastandwasswollen.Ampicillin2gmIVq6hwasbegunbutthepatientremainedfebrilethenext24hours.

Whichofthefollowingisthemostappropriatemanagement:

A. CT‐guidedbiopsyoftheaffectedkidneyB. AddgentamicinC. ChangeampicillintodaptomycinD. Checkurinefor“decoy”cellsofBKvirusE. Continueampicillinatsamedose

Answer:E

Rationale:Thefindingsareconsistentwith“lobarnephronia”oracutefocalbacterialnephritis.Thisformofacutepyelonephritisischaracterizedbyedemaandinflammationofoneoroccasionally2kidneylobes.Ifnottreatedadequately,theaffectedlobecanliquefyandformarenalcorticalabscess.Responsetotherapyisusuallysomewhatslowerthanpyelonephritisandrelapseisprobablymorecommoniflessthanthreeweeksoftreatmentaregiven.Responseofenterococcalpyelonephritistolevaquinissuboptimal,butmayreduceabnormalitiesoftheurinalysisandurineculture.BKviruriacausesrenalfailurebutnotfeverinrenalallograftrecipients.Daptomycinwouldnotbeindicatedforanampicillin‐susceptibleE.faecalis.Unlikeenterococcalendocarditis,additionofanaminoglycosideisnotnecessaryintreatingenterococcalurinarytractinfection.

#41A35‐year‐oldEgyptianmale,studyinginBoston,wasseenbecauseofmicroscopichematuriapickeduponaroutinephysicalexamination.Heunderwentcytoscopy.Abiopsyisshownofhisbladderwall,wherearoughened,dullsurfacewasfoundinseveralareasofthebladder.Helikelyacquiredthisinfectionfromwhichofthefollowingsources?

A. WadingintheNileriverB. EatingpoorlycookedlambC. DrinkingwellwaterD. InsectbiteE. Eatinghumanstool

Answer:A

Rationale:TheeggsofSchistosomahaematobiumarerecognizablebythespikeatthetip,notonthesidelikeSchistosomamansoni.Theeggsoriginateintheadultschistosomelivinginaveinofthevesicleorpelvicplexusandmigrateintothewallofthebladder,causinghematuria,andarethenexcretedintotheurine.Excretedeggshatchintomiracidiawhichtheninfectsnailswhichreleasemotilecercaria.Infectionisacquiredwhenwadinginwaterinwhichinfectedsnailshaveproducedcercariathatswimuntiltheycaninvadeintactskinofthehost.PartsoftheNileRiverhavebeennotableforthepopulationofinfectedsnailsandpersonswithschistosomiasis,bothmansoniandhaematobium

#42

Whichofthefollowingorganismsisthemostlikelycauseofthispenilelesionof7monthsduration:

A. HumanpapillomavirusB. HaemophilusducreyiC. TreponemapallidumD. KlebsiellagranulomatisE. Chlamydiatrachomatis

Answer:D

Rationale:Thischroniculceratedpenilelesionresemblesgranulomainguinale,aninfectioncausedbyabacteriumthanhasnotbeencultured,namedCalymmatobacteriumgranulomatis.SequencingoftheorganismhasfoundacloserelationshiptoKlebsiella,hencearenamingasKlebsiellagranulomatis.Granulomainguinaleistheclassiccauseofchronicgenitalulcersthatbecomeincreasinglydisfiguring.Syphilitisulcersgenerallyhealwithin3‐12weeks.Chancroidcanalsobechronicbuttheselesionsshouldbepainful..Diagnosisisbydemonstratingtheorganismsinmacrophages,calledDonovanbodies,usingWright‐Giemsastain.Trimethoprim‐sulfamethoxazoleordoxycyclinearetreatmentsofchoice.

#43ThisbrainsectionwastakenfromautopsyofanHIV‐infectedpatient.Theoriginofthisinfectionwasprobablyexposureto:

A. CatstoolB. HumanstoolC. MosquitoesD. TicksE. Lice

Answer:A

Rationale:ThestructureisacystofToxoplasmagondii,aninfectionacquiredfromingestionofoocystsincatstoolorcystsininadequatelycookedmeatfromsheeporcows.Humansdonotexcreteoocystsintheirstool.Insectsarenotvectorsoftoxoplasma.

#44This44‐year‐oldmanwithAIDShasanorganisminhisskinwhichcanspreadtowhichofthefollowingsites:

A. ConjunctivaB. BuccalmucosaC. Brain D. BloodstreamE. Draininglymphnodes

Answer:A

Rationale:Thepapulewithashinycenteristypicalofmolluscumcontagiosum,aninoculationviraldiseaseseeninimmunosuppressedand,lessoften,inotherwisehealthypatients.Molluscumcanspreadtootherareasofthepatient’sskinorconjunctivabyinoculation.Spreadtobuccalmucosawouldberare.Lymphaticspreadorhematogenousdisseminationtobrainorbloodstreamdoesnotoccur.