Evaluation of nine immunoassay kits (enzyme immunoassay and direct fluorescence) for detection of Giardia lamblia and Cryptosporidium parvum in human fecal specimens

Abstract

It is well known that Giardia lamblia and Cryptosporidium parvum can cause severe symptoms in humans, particularly those who are immunologically compromised. Immunoassay procedures offer both increased sensitivity and specificity compared to conventional staining methods. These reagents are also helpful when screening large numbers of patients, particularly in an outbreak situation or when screening patients with minimal symptoms. The data obtained by using 9 diagnostic kits were compared: direct fluorescent-antibody assay (DFA) kits (TechLab Giardia/Crypto IF kit, TechLab Crypto IF kit, and Meridian Merifluor Cryptosporidium/Giardia) and enzyme immunoassay (EIA) kits (Alexon ProSpecT Giardia EZ Microplate Assay, Alexon ProSpecT Cryptosporidium Microplate Assay, Cambridge Giardia lamblia Antigen Microwell ELISA, Meridian Premier Giardia lamblia, Meridian Premier Cryptosporidium, TechLab Giardia CELISA, Trend Giardia lamblia EIA). The test with the Meridian Merifluor Cryptosporidium/Giardia kit was used as the reference method. In various combinations, 60 specimens positive for Giardia, 60 specimens positive for Cryptosporidium, 40 specimens positive for a Giardia-Cryptosporidium mix, and 50 negative fecal specimens were tested. Different species (nine protozoa, three coccidia, one microsporidium, five nematodes, three cestodes, and one trematode) were included in the negative specimens. The sensitivity of EIA 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% (Alexon) to 99% (Meridian Premier); specificities were 100%. All DFA results were in agreement, with 100% sensitivity and specificity; however, the TechLab reagents resulted in fluorescence intensity that was generally one level below that seen with the reagents used in the reference 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.

Diagnosis and Treatment of Acute or Persistent Diarrhea

“…Fluorescence-labeled antibodies against specific parasites have improved the sensitivity and specificity of epifluorescence microscopy analyses to 98%-100%. 12 Many laboratories have replaced diagnostic methods, based on microscopy of fecal samples, with more sensitive and specific (and less observer-dependent) enzyme-linked immunoabsorbent assay (ELISA) methods; ELISA is used to detect protozoa such as Giardia and Cryptosporidium in fecal samples. PCR analysis can detect most protozoan infections and is more sensitive than antibody detection methods, [13][14][15] although these assays are still not performed routinely in the clinic.…”

HIV/AIDS cholangiopathy: Clinical spectrum, cholangiographic features and outcome in 30 patients

“…[2][3][4][5][6][7]23,24 We also did not employ advanced methods of detection such as immunoassay tests or immunohistochemistry. 25,26 A significant strength is the fairly large number of patients with HIV cholangiopathy and follow-up from a single center in whom treatment with sphincterotomy and or HAART resulted in reversal of cholangiopathy in a third of patients.…”

Comparison of Direct Immunofluorescence, Immunoassays, and Fecal Flotation for Detection of Cryptosporidium spp. and Giardia spp. in Naturally Exposed Cats in 4 Northern California Animal Shelters

“…16,17 have raised awareness of the human health risks and motivated the development of new diagnostic tests for people. Although extensively validated in people, [18][19][20][21] few studies document the performance characteristics (eg, sensitivity, specificity, ease of use) of these tests in cats. 22 A recent study 22 examined several commercially available immunoassays for the diagnosis of Cryptosporidium spp.…”