Routine culture of Giardia lamblia trophozoites from human duodenal aspirates.
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ABSTRACT: Formerly, thestudyofvarious species oftheparasite genus Giaidia was limited owing todifficulty inobtaining cultured stocks forstudy. Thissituation haschanged over thepast20years,anda numberofmethodsfortheexcysta- tionandculturing ofGiardia spp. havebeendescribed. In this paper we describe a refinement ofsome ofthese methods foruse intheisolation andpropagationofGiari-dia trophozoites forexperimental purposes. Giardia mniishasbeenextensively studied byusingthe mouse model,butan equivalent modelforthestudyof Giar-dia diuodenalis hasnotyetbeengenerally accepted. For this reason,we tested gerbils (Men-ionies mmnguicildatis) as an animal modelfortheexcystmentofGiardia fromhumans, wildmeadowvoles(Microtus pennsylv'anicils), domestic dogs(Canis familiaris), andbeavers (Castor- catndenisis) by using themethods ofBelosevic etal.(4). We were ableto culture trophozoites obtained fromgerbils infected with human,dog,andbeaverGiairdia isolates, butnot vole Giairdia isolates, byusing DiamondTYI-S-33 medium.The Giardia isolates extracted fromvoles were assumed tobeG. maniis, andtheGiardia isolates extracted fromhumans, dogs, andbeavers were assumed tobeG. diuodenalis, using theterminology ofFilice (9). MATERIALS AND METHODS Sources ofGiardia spp.Cysts were obtained frombeaver, dog,andhumanfeces. Thebeaver feces were obtained from a smallpond3km northoftheKananaskis FieldStation in southwestern Alberta, Canada.Infested dogfeceswere obtained fromtheCalgary AnimalShelter, Calgary, Alberta, andhumanstools containing Giairdia cystswere obtained fromtheAlberta Provincial Health Laboratory andFoothills General Hospital inCalgary, Alberta, orfromtheUniversity ofAlberta Hospital, Edmonton. Allfecal specimens obtained inCalgary were shipped directly toour laboratory over ice within 6hofexcretion andwere processed immediately. G. manistrophozoites were obtained bystripping theentire small intestines ofnaturally infected meadow volesthatwere trapped live inthevicinity oftheKananaskis FieldStation. Cystconcentration. Beaverfecesconsisted mostly oflarge particulate matterthatwas easily separated fromthefiner sediment andcystsbystraining andrinsing withphosphate-