Medical Microbiology

330 4 BacteriaasHumanPathogens

inpatientserumusingaquantitativelysis-agglutinationtest.Viableculture

strainsoftheregionallyendemicserovarsprovidethetestantigens.The

reactionisreadoffunderthemicroscope.

Therapy.TheagentofchoiceispenicillinG.

Epidemiologyandprevention.Leptospirosesaretypicalzoonoticinfections.

Theyarereportedfromeverycontinentinbothhumansandanimals.The

mostimportantsourcesofinfectionarerodentsanddomesticanimals,

mainlypigs.The animalsexcretethepathogenwithurine.Leptospirae

showlittleresistancetodryingoutsothatinfectionsonlyoccurbecause

ofcontactwithamoistmilieucontaminatedwithurine.Thepersonsmost

atriskarefarmers,butchers,sewagetreatmentworkers,andzoostaff.

Preventionoftheseinfectionsinvolvesmainlyavoidingcontactwithmate-

rialcontainingthepathogens,controlofMuridaerodentsandsuccessful

treatmentofdomesticlivestock.Itisnotnecessarytoisolateinfectedpersons

ortheircontacts.Thereisnocommerciallyavailablevaccine.

Rickettsia,Coxiella,Orientia,andEhrlichia

(Typhus,SpottedFever,QFever,Ehrlichioses)

&ThegeneraoftheRickettsiaceaeandCoxelliaceaecontainshort,coccoid,

smallrodsthatcanonlyreproduceinhostcells.WiththeexceptionofCoxiella

(aerogenictransmission),theyaretransmittedtohumansviathevectorslice,

ticks,fleas,ormites.R.prowazekiiandR.typhicausetyphus,adiseasechar-

acterizedbyhighfeverandaspottyexanthem.Severalrickettsiaespecies

causespottedfever,amildertyphuslikedisease.Orientiatsutsugamushiis

transmittedbymitelarvaetocausetsutsugamushifever.Thisdiseaseoccurs

onlyinAsia.CoxiellaburnetiiisresponsibleforQfever,aninfectioncharac-

terizedbyapneumoniawithanatypicalclinicalcourse.

SeveralspeciesofEhrlichiaceaecauseehrlichiosisinanimalsandhumans.

Themethodofchoiceforlaboratorydiagnosisofthevariousrickettsiosesand

ehrlichiosesisantibodyassaybyanyofseveralmethods,inmostcasesin-

directimmunofluorescence.Tetracyclinesrepresenttheantibioticofchoice

foralloftheseinfections.TyphusandspottedfevernolongeroccurinEurope.

Qfeverinfectionsarereportedfromallovertheworld.Sourcesofinfection

includediseasedsheep,goats,andcattle.Theprognosisfortherarechronic

formofQfever(syn.Qfeverendocarditis)ispoor.Ehrlichiosisinfectsmainly

animals,butinrarecaseshumansaswell. &

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Kayser, Medical Microbiology © 2005 Thieme