Microbiology and Food Safety

Abstract

Many different screening devices and sampling methods have been used to detect the presence of naturally occurring Salmonella on commercially processed broiler carcasses . The objective of this study was to compare 2 commercial screening systems (BAX and Roka) to a standard cultural procedure used by industry and government laboratories . On each of 5 replicate sampling days (5 flocks), 8 broiler carcasses were collected after chilling from a commercial broiler plant . Each carcass was rinsed with 400 mL of 1% buffered peptone water (BPW) for 60 s using an automated shaking machine . A 30-mL aliquot was removed and incubated at 35°C for 24 h . After incubation, pre-determined aliquots of the 30 mL BPW were inoculated into the BAX and Roka instruments (according to the manufacturer’s protocol); 0 .1 mL and 0 .5 mL aliquots (respectively) were also inoculated into tetrathionate (TT (Hajna)) and Rappaport-Vassiliadis (RV) broths which were incubated at 42°C for 24 h . Following incubation, aliquots from the 2 broths were streaked for isolation onto xylose-lysinetergitol 4 and brilliant green sulfa agar plates and incubated at 35°C for 24 h . One typical Salmonella-like colony from each of the 4 plates was selected and screened biochemically and confirmed as Salmonella by serological methods. The BAX, which is a PCR amplification system, and the Roka, which uses the Atlas System to target the ribosomal RNA, both detected the same positive samples as the conventional methodology . Four of 40 samples were positive for Salmonella with no false positives or false negatives detected from either automated system . Both rapid methods tested in this study were equally as effective as the more laborious and time-consuming conventional cultural procedure .