Medical Microbiology

320 4 BacteriaasHumanPathogens

Treponema(Syphilis,Yaws,Pinta)

&Treponemapallidum,subsp.pallidumisthecausativepathogenofsyphilis.

Treponemesfeature 10 – 20 primaryspiralwindingsandcanbeviewedusing

darkfieldmicroscopy.Theycannotbegrownonartificialnutrientculture

mediums.Syphilisaffectsonlyhumans.Thepathogensaretransmittedby

directcontact,inmostcasesduringsexualintercourse.Theyinvadethesub-

cutaneousandsubserousconnectivetissuesthroughmicrotraumatainskin

ormucosa.Thediseaseprogressesinstagesdesignatedasprimary,second-

ary,andtertiarysyphilisorstagesI,II,andIII.StageIischaracterizedbythe

painlessprimaryaffectandlocallymphadenitis.Disseminationleadstostage

II,characterizedbypolylymphadenopathyaswellasgeneralizedexanthem

andenanthem.StageIIIissubdividedintoneurosyphilis,cardiovascularsy-

philis,andgummatoussyphilis.InstagesIandIIthelesionpathogenscanbe

viewedunderadarkfieldmicroscope.AntibodyassaysincludetheVDRLfloc-

culationreaction,TP-PAparticleagglutination,andtheindirectimmuno-

fluorescencetestFTA-ABS.ThetherapeuticofchoiceispenicillinG.Thisdis-

easeisknowninallpartsoftheworld.Preventivemeasuresconcentrateon

protectionfromexposure.OtherTreponema-causeddiseasesthatdonotoc-

curinEuropeincludenonvenerealsyphilis,causedbyT.pallidum,subsp.en-

demicum,yaws,causedbyT.pallidum,subsp.pertenue,andpinta,causedby

Treponemacarateum. &

ThegenusTreponemabelongstothefamilyofSpirochaetaceaeandincludes

severalsignificanthumanpathogenspeciesandsubspecies.T.pallidum,

subsp.pallidumisthesyphilispathogen.T.pallidum,subsp.endemicumis

thepathogenthatcausesasyphilislikediseasethatistransmittedbydirect,

butnotsexualcontact.T.pallidum,subsp.pertenueisthepathogenthat

causesyaws,andT.carateumcausespinta,twononvenerealinfections

thatoccurinthetropicsandsubtropics.

Treponemapallidum,subsp.pallidum(Syphilis)

Morphologyandculture.Theseorganismsareslenderbacteria,0.2lmwide

and 5 – 15 lmlong;theyfeature 10 – 20 primarywindingsandmovebyrotat-

ingaroundtheirlengthwiseaxis.Theirsmallwidthmakesitdifficulttoren-

derthemvisiblebystaining.Theycanbeobservedinvivousingdarkfield

microscopy.In-vitroculturinghasnotyetbeenachieved.

Pathogenesisandclinicalpicture.Syphilisaffectsonlyhumans.Thedisease

is normally transmitted by sexualintercourse. Infection comes about

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Kayser, Medical Microbiology © 2005 Thieme