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False-positive results obtained with the Alexon ProSpecT Cryptosporidium enzyme immunoassay
K M Doing1, J L Hamm, J A Jellison
1Department of Microbiology, Biochemistry and Molecular Biology, University of Maine, Orono, Maine 04469, USA. doing@maine.maine.edu
Abstract:
Cryptosporidium is known to cause diarrhea in immunocompromised patients and is also associated with outbreaks of disease due to food-borne and waterborne parasites. Traditional procedures, involving iodine staining of wet mounts of stool sediments and trichrome staining, lack the sensitivity to detect Cryptosporidium. Special staining procedures, such as the modified acid-fast and safranin stains, are generally employed. Less labor-intensive antigen detection assays have simplified detection; however, careful attention to local epidemiology is important because false-positive tests occur. Here, we report two incidents involving 62 false-positive results obtained with the Alexon ProSpecT Cryptosporidium enzyme immunoassay, which were deemed false-positive based on negative results obtained from extensive microscopic examinations.
Insights
False-positive results from the Alexon ProSpecT Cryptosporidium enzyme immunoassay were identified in two incidents. Extensive microscopic examinations confirmed these results were false positives, highlighting the need for careful interpretation of diagnostic tests for Cryptosporidium.
Area of Science:
- Medical Parasitology
- Diagnostic Microbiology
- Clinical Immunology
Background:
- Cryptosporidium causes diarrhea, particularly in immunocompromised individuals.
- Food-borne and waterborne outbreaks are linked to this parasite.
- Traditional diagnostic methods like iodine and trichrome staining lack sensitivity for Cryptosporidium detection.
Purpose of the Study:
- To report incidents of false-positive results with the Alexon ProSpecT Cryptosporidium enzyme immunoassay.
- To emphasize the importance of corroborating immunoassay results with microscopic examination.
- To highlight potential diagnostic challenges in identifying Cryptosporidium infections.
Main Methods:
- Two incidents involving the Alexon ProSpecT Cryptosporidium enzyme immunoassay were investigated.
- Extensive microscopic examinations of stool sediments were performed.
- Results from the enzyme immunoassay were compared with microscopic findings.
Main Results:
- A total of 62 false-positive results were identified across two incidents.
- Microscopic examinations consistently yielded negative results, contradicting the immunoassay findings.
- The Alexon ProSpecT assay demonstrated a propensity for false-positive outcomes in these cases.
Conclusions:
- The Alexon ProSpecT Cryptosporidium enzyme immunoassay can produce false-positive results.
- Microscopic examination remains a critical method for confirming Cryptosporidium diagnoses.
- Clinical laboratories should exercise caution and consider confirmatory testing when interpreting immunoassay results for Cryptosporidium.