EVALUATION OF 9 IMMUNOASSAY KITS (ENZYME-IMMUNOASSAY AND DIRECT FLUORESCENCE) FOR DETECTION OF GIARDIA-LAMBLIA AND CRYPTOSPORIDIUM-PARVUM IN HUMAN FECAL SPECIMENS

It is well known that Giardia lamblia and Cryptosporidium parvum can c ause severe symptoms in humans, particularly those who are immunologic ally compromised. Immunoassay procedures offer both increased sensitiv ity and specificity compared to conventional staining methods. These r eagents are also helpful when screening large numbers of patients, par ticularly in an outbreak situation or when screening patients with min imal symptoms. The data obtained by using 9 diagnostic kits were compa red: direct fluorescent antibody assay (DFA) kits (TechLab Giardia/Cry pto IF kit, TechLab Crypto IF kit, and Meridian Merifluor Cryptosporid ium/Giardia) and enzyme immunoassay (EIA) kits (Alexon ProSpecT Giardi a EZ Microplate Assay, Alexon ProSpecT Cryptosporidium Microplate Assa y Cambridge Giardia lamblia Antigen Microwell ELISA, Meridian Premier Giardia lamblia, Meridian Premier Cryptosporidium, TechLab Giardia CEL ISA, Trend Giardia lamblia EIA). The test with the Meridian Merifluor Cryptosporidium/Giardia kit was used as the reference method. In vario us combinations, 60 specimens positive for Giardia 60 specimens positi ve for Cryptosporidium, 40 specimens positive for a Giardia-Cryptospor idium mix, and 50 negative fecal specimens were tested. Different spec ies (nine protozoa, three coccidia, one microsporidium, five nematodes , three cestodes, and one trematode) were included in the negative spe cimens. The sensitivity of ELA for Giardia ranged from 94% (Alexon) to 99% (Trend and Cambridge); the specificity was 100% with all EIA kits tested. The sensitivity of EIA for Cryptosporidium ranged from 98% (A lexon) to 99% (Meridian Premier); specificities were 100%. All DFA res ults were in agreement, with 100% sensitivity and specificity; however , the TechLab reagents resulted in fluorescence intensity that was gen erally one level below that seen with the reagents used in the referen ce method. In addition to sensitivity and specificity, factors such as cost, simplicity, ease of interpretation of results (color, intensity of fluorescence), equipment, available personnel, and number of tests ordered are also important considerations prior to kit selection.