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Detection of verotoxin in stool specimens
A C Maniar1, T Williams, C M Anand
1Cadham Provincial Laboratory, Winnipeg, Manitoba, Canada.
Journal of Clinical Microbiology
|January 1, 1990
Summary
Counter-current immunoelectrophoresis (CIE) detected verotoxin (VT) in 85.6% of positive fecal specimens. A faster Vero cell suspension culture method also proved reliable for verotoxin detection.
Area of Science:
- Microbiology
- Immunology
- Diagnostic Testing
Background:
- Verotoxin (VT) producing bacteria, particularly E. coli O157:H7, are significant causes of diarrheal illness and hemolytic uremic syndrome.
- Accurate and rapid detection of verotoxin is crucial for patient management and public health surveillance.
Purpose of the Study:
- To evaluate the diagnostic performance of counter-current immunoelectrophoresis (CIE) for verotoxin detection in fecal specimens.
- To compare the efficiency of Vero cell suspension cultures with traditional Vero cell monolayers for verotoxin detection.
Main Methods:
- Counter-current immunoelectrophoresis (CIE) was performed on 132 fecal specimens confirmed to contain verotoxin.
- Additional E. coli O157 specimens negative by Vero cell monolayer assay were tested by CIE.
- 302 verotoxin-positive filtrates were re-assayed using Vero cell suspension cultures in microdilution plates.
Main Results:
- CIE identified verotoxin in 85.6% of initially positive specimens and 8.5% of E. coli O157 specimens.
- CIE demonstrated a specificity of 93.7% and a sensitivity of 85.6%, with potential false positives attributed to anti-O157 antibodies.
- Vero cell suspension cultures detected cytotoxic effects in 93% of specimens within 24 hours and the remainder within 48 hours, offering faster results than monolayers.
Conclusions:
- Counter-current immunoelectrophoresis (CIE) is a moderately sensitive and specific method for verotoxin detection, though limitations exist.
- Vero cell suspension culture offers a reliable and significantly faster alternative to Vero cell monolayers for verotoxin detection, improving diagnostic turnaround time.