Lynne Shore Garcia

Diagnostic Medical Parasitology


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PA. 2006. Diagnosing infection levels of four human malaria parasite species by a polymerase chain reaction/ligase detection reaction fluorescent microsphere-based assay. Am J Trop Med Hyg 74:413–421. PMID 16525099

8 Parasite Recovery: Culture Methods, Animal Inoculation, and Xenodiagnosis
Culture methods Intestinal protozoa Pathogenic free-living amebae Blastocystis spp. (Blastocystis hominis) Pathogenic flagellates Flagellates of blood and tissue Toxoplasma gondii Plasmodium and Babesia spp. Cryptosporidium spp. Microsporidia Animal inoculation Leishmania spp. Trypanosoma spp. Toxoplasma gondii Xenodiagnosis

      Very few clinical laboratories offer specific culture techniques for parasites. The methods for in vitro culture are often complex, while quality control is difficult and not really feasible for the routine diagnostic laboratory. In certain institutions, some techniques may be available, particularly when consultative services are provided (reference laboratory situation) and for research purposes. However, most laboratories do not offer these techniques.

      Few parasites can be routinely cultured; however, methods are available for Entamoeba histolytica, Naegleria fowleri, Acanthamoeba spp., Trichomonas vaginalis, Dientamoeba fragilis, Toxoplasma gondii, Blastocystis spp., Trypanosoma cruzi, and the leishmanias. Often, when specimens are cultured for potential pathogens, nonpathogenic protozoa could also be recovered. These procedures are usually available only after consultation with the laboratory and on special request. For those who may be interested in trying these techniques, the several different media presented below are representative of those available. More extensive options can be found in the literature (113).

      Cultures of parasites grown in association with an unknown microbiota are referred to as xenic cultures. A good example of this type of culture would be stool specimens cultured for E. histolytica. If the parasites are grown with a single known bacterium, the culture is referred to as monoxenic. An example of this type of culture would be clinical specimens (corneal biopsy specimens) cultured with Escherichia coli as a means of recovering species of Acanthamoeba and Naegleria. If parasites are grown as pure culture without any bacterial associate, the culture is referred to as axenic. An example of this type of culture would be the use of media for the isolation of Leishmania spp. or Trypanosoma cruzi.