Medical Microbiology

— DifferentiationofE.histolyticaandE.dispar.AnewtypeofPCRisnow

usedinspecializedlaboratoriesthatfacilitatesdirectdetectionofthese

amebicspeciesinstoolspecimensaswellasadifferentialdiagnosis.

— Detectionofcoproantigen.E.histolyticaantigencanbedetectedinstool

specimensusinganELISAbasedonmonoclonalantibodieswithhighlev-

elsofsensitivityandspecificity.

— Serologicalantibodyassay.Antibodiescanbedetectedserologicallyin

95 – 100 %ofpatientswithamebicliverabscess.Thisisalsofrequently

thecaseininvasiveintestinalamebosiscausedbyE.histolytica.Onthe

otherhand,antibodiesareproducedfarlessofteninE.disparinfections.

WhenstagesoftheE.histolytica/E.disparcomplexaredetectedinstool,

thepresenceorabsenceofserumantibodiescanbeusedindifferential

diagnosisofinvasivevs.noninvasiveintestinalamebosis.

&Extraintestinalamebosis.Thistypeofamebosisisdiagnosedwiththe

helpofclinicalmethods(ultrasound,computertomography,etc.)andsero-

logicalantibodydetection(seeabove).

Therapy.Nitromidazolederivativesareeffectiveagainstsymptomaticintes-

tinalandextraintestinalformsofamebosis.Ontheotherhand,amebicides

withonlyluminalactivityareeffectiveagainstasymptomaticintestinalame-

bosis(e.g.,diloxanidefuroate)(Table9. 5 ).Anewdrugagainstintestinalame-

bicinfectionsisnitazoxandide.Besideschemotherapy,othermeasuresmay

alsoberequired,e.g.,surgeryandsymptomatictreatmentforliverabscesses.

Prevention. Travelerstoendemicareasshoulddecontaminate drinking

waterbyboilingorfilteringit(e.g.,withKatadynfilters),noteatsalads,

eatonlyfruittheyhavepeeledthemselvesandexercisecautionwhenit

comestochangingtheirdiet.Chemoprophylacticdugsarenotavailable.

506 9 Protozoa

Table9. 5 ChemotherapyinAmebosis(examples)

Groupofamoebicides* Activesubstance Indication

Luminalamebicides Diloxanidefuroate

Paromomycin

Nitazoxanide

Asymptomaticcystexcreters,

follow-uptreatmentofinvasive

intestinalform

Systemicamebicides Nitroimidazoles:

Metronidazole

Ornidazole

Tinidazole

Invasiveintestinalandextrain-

testinalforms

*Applicationperos

9

Kayser, Medical Microbiology © 2005 Thieme