RapidChek SELECT Salmonella. Performance Tested Method 080601.

RapidChek SELECT Salmonella was previously validated in the Performance Tested Methods program for the detection of Salmonella spp. in raw ground chicken, chicken carcass rinse, sliced cooked turkey, and liquid eggs. The present matrix extension study conducted under the AOAC Research Institute Emergency Response Validation program compared the RapidChek SELECT Salmonella method to the U.S. Food and Drug Administration's Bacteriological Analytical Manual (FDA-BAM) method for the detection of Salmonella Typhimurium in peanut butter. Overall, 27 samples were found positive by the RapidChek SELECT Salmonella method and 27 were found to be positive by the reference method. All RapidChek SELECT Salmonella presumptive positives were confirmed positive by the cultural reference method; additionally, all presumptive negative results were confirmed negative by the cultural reference method. Accordingly 0% false-negative rate and 0% false-positive rate were found. No significant difference between the RapidCheck SELECT Salmonella and FDA-BAM reference method was found; calculated Chi-square was 0. Results indicate that a low level of Salmonella in peanut butter can be successfully recovered and detected in the minimum 24 h enrichment protocol.

Bacteriophage-based enrichment coupled to immunochromatographic strip-based detection for the determination of Salmonella in meat and poultry.

Immunochemical-based methods for the detection of Salmonella in food can be complicated by the presence of closely related, immunocrossreactive non-Salmonella species in the sample that may cause false-positive results. To circumvent this problem, specific bacteriophages against immunocrossreactive, non-Salmonella bacteria were used in the sample enrichment step to suppress their growth and improve the performance of an immunochromatographic strip-based detection method for Salmonella. Cross-reactive bacteria were isolated from various food sources and were characterized with a panel of Salmonella somatic O antigen-specific monoclonal antibodies. These cross-reactive bacteria were primarily Citrobacter spp. and Escherichia coli with serology shared with Salmonella serogroups B, D, and F. These bacteria were used as hosts for the isolation of specific lytic bacteriophages. When formulated with the primary enrichment, the bacteriophage cocktail significantly reduced false positives with a broadly reactive immunochromatographic test strip. This was demonstrated in both artificially and naturally contaminated meat. False positives in naturally contaminated beef samples were reduced from 32 of 115 samples tested to zero. In raw meat and poultry with a relatively high bioburden (>10(5) CFU/g), the use of the bacteriophage-based enrichment procedure gave improved recovery of Salmonella compared with the conventional culture-based reference method. This was observed when coupled to either test strip-based or selective agar-based detection. The use of specific bacteriophages for the control of immunocrossreactive and competitive microflora during the food sample enrichment step provides a new approach for enhancing the performance of both immunological- and cultural-based detection methods.