Evaluation of three commercial assays for the detection of Giardia and Cryptosporidium organisms in stool specimens

Abstract number: 1733_23

Dauby N., Moens C., Mohamed S., Van den Wijngaert S., Vandenberg O., Dediste A.

Objectives:Giardia is known as the most common pathogenic intestinal protozoa in Belgium, yet Cryptosporidium remains frequently under diagnosed. We compared three commercial assays for the detection of Giardia and Cryptosporidium.

Methods: Stool specimens were collected from 101 children attending a day care centre located in Brussels. Most of those children presented abdominal complaints and/or diarrhoea since two weeks. Therefore, we wanted to investigate this outbreak in order to exclude a parasitic etiology. Stool specimens were examined according to our specific Triple-Feces-Test (TFT) protocol which consists in 3 samples collected on 3 consecutive days (2 with SAF preservative and one fresh specimen) examined with and without concentration techniques and a permanent staining. In addition, a Rhodamine-auramine O staining for Cryptosporidium is performed on the fresh specimen, with confirmation with Kinyoun carbolfuchsin acid-fast staining. Results obtained with our protocol were compared with those from Prospect Crypto/Giardia® (ELISA), ImmunoCard STAT® (IC) and Merifluor® direct fluorescent-antibody (DFA) commercial tests, each of them performed on the unpreserved stool specimen.

Results: Among the 101 children included in the study, 5 and 17 were infected with G. lamblia and Cryptosporidium respectively. The sensitivity of the TFT-protocol was 100% for Giardia which was similar to the sensitivity of the IC and ELISA tests. The specificity of all tested methods was never lower than 97%. The sensitivity of the IC and the ELISA for the detection of Cryptosporidium were 100% and 95.3% respectively compared to 52.9% for the microscopic examination. When we used DFA as screening methods for the diagnosis of Giardia or Cryptosporidium, we found a sensitivity of 80% and 82% respectively. Specificity of the DFA was 100% and 97.6% for Giardia and Cryptosporidium respectively.

Conclusion: Microscopy with the TFT protocol is very sensitive for detection of Giardia but less sensitive for detection of Cryptosporidium than the three commercial kits tested. Regarding to our results, we should consider including ELISA or IC tests in our TFT-protocol for a more reliable detection of Crytosporidium.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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