Medical Microbiology

322 4 BacteriaasHumanPathogens

oftheVenerealDiseaseResearchLaboratory(USA)andisknownasthe

VDRLflocculationreaction.

&Antitreponemaantibodies.ProbablydirectedatT.pallidum.

— Treponemapallidumparticleagglutination(TP-PA).Thistestformathas

widelyreplacedtheTreponemapallidumhemagglutinationassay(TPHA).

Theantigens(ultrasonically-treatedsuspensionofTreponemapallidum,

Nicholsstrain,culturedinrabbittesticles)arecoupledtoparticlesor

erythrocytes.

— Immunofluorescencetest(FTA-ABS).Inthisfluorescencetreponemal

antibodyabsorptiontesttheantigenconsistsofkilledNicholsstrain

treponemesmountedonslidesandcoatedwithpatientserum.Bound

antibodiesare detectedbymeans offluorescein-markedantihuman

IgGantibodies.SelectiveantitreponemeIgMantibodiescanbeassayed

(= 1 9S-FTA-ABS)usingantihumanIgMantibodies(lcapturetest).

— Treponemapallidumimmobilizationtest(TPItest).Livingtreponemes

(Nicholsstrain)areimmobilizedbyantibodiesinthepatientserum.This

testisnolongerusedinroutinediagnostics.Itisconsideredthegold

standardforevaluationofantitreponemeantibodytests.

Theantibodytestsareusedasfollows:

— Screening:TP-PAorTPHA(qualitative).

— Primarydiagnostics:TP-PAorTPHA,VDRL,FTA-ABS(allqualitative).

— Specialdiagnostics:VDRL(quantitative); 1 9S-FTA-ABS.

TherapeuticsuccesscanbedeterminedbythequantitativeVDRLtest.Arapid

dropinreaginsindicatesanefficacioustherapy.The 1 9S-FTA-ABScanbeused

tofindanswerstospecializedquestions.Example:doesapositiveresultin

primarydiagnostictestingindicateaserologicalscarorafreshinfection?

Treponemapallidum

Fig.4. 23 Seroustransudate

frommoistmucocutaneous

primarychancre.Directim-

munofluorescence.

4

Kayser, Medical Microbiology © 2005 Thieme