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Fluorescent antibody method for the detection of Salmonella: development, evaluation, and collaborative study
Journal - Association of Official Analytical Chemists
|July 1, 1975
Summary
A new fluorescent antibody (FA) method for Salmonella detection shows high accuracy, with the Selenite Cystine (SC) enrichment technique yielding the best results. Training is crucial for reliable Salmonella screening in food products.
Area of Science:
- Food Microbiology
- Immunology
- Analytical Chemistry
Background:
- Commercial polyvalent fluorescent antibody (FA) preparations require evaluation for specificity and cross-reactivity.
- A reliable FA method is needed for screening Salmonella in various food products.
- Existing AOAC (Association of Official Analytical Chemists) methods serve as a benchmark for validation.
Purpose of the Study:
- To develop and validate a fluorescent antibody (FA) method for Salmonella detection in food products.
- To compare the performance of the FA method against the official AOAC method.
- To determine the optimal enrichment and post-enrichment techniques for the FA assay.
Main Methods:
- Evaluation of commercial FA preparations for specificity and cross-reactivity.
- Screening of approximately 4000 product samples using the developed FA method.
- A two-phase collaborative study involving experienced and inexperienced analysts, testing inoculated and naturally contaminated food samples.
- Comparison of four enrichment/post-enrichment combinations (Selenite Cystine (SC) and Tetrathionate (TT) broths) with the FA method.
Main Results:
- The FA method demonstrated a low false-negative rate (4 out of 619 positive samples) and a 7% false-positive rate in initial screening.
- The SC-SC (Selenite Cystine enrichment followed by Selenite Cystine post-enrichment) combination showed the highest correlation with the AOAC method.
- Experienced analysts achieved excellent agreement with the AOAC method (no false-negatives, 2 false-positives), while inexperienced analysts showed higher error rates.
- Training in FA methodology was identified as essential for accurate results.
Conclusions:
- The developed FA method, particularly when using SC-SC enrichment, is a reliable and effective tool for Salmonella detection in food products.
- The SC-SC enrichment and post-enrichment strategy provides the best correlation with established AOAC culture methods.
- Adequate training in FA methodology is critical for analysts to achieve accurate and reproducible results, ensuring reliable Salmonella screening.