Purpose: To evaluate the Roka Salmonella Detection Assay system for the detection of Salmonella enterica spp. in food and environmental surfaces in an AOAC Research Institute Performance Tested Method SM study utilizing Roka’s high throughput, fully automated instrument – AtlasTM System.
Methods: The method included a single 12 or 16 hours enrichment for perishables or 24 hours enrichment for non-perishables and environmental surfaces. After sample transfer to the instrument collection tube, lysis of bacteria, template specific sample extraction, amplification and probe detection were all performed on the instrument. A total of 12 foods, including two 375-g composites, and 3 environmental surfaces were compared to a cultural reference method in an internal study; 4 foods and 1 environmental surface in an external study. Selectivity was evaluated by testing 100 target microorganisms and 30 non-target microorganisms.
Results: The test method provided a positive result for 100% of 100 target microorganisms, and a negative result for 30 non-target microorganisms. No significant differences were observed between the test method and the cultural reference method for raw ground beef, raw ground chicken, deli-cooked turkey, raw cod, dried milk, string cheese, milk chocolate, cocoa powder, cookie dough, nacho cheese seasoning, sealed concrete and plastic. Dried egg in the internal study and peanut butter in the external study had a higher number of confirmed test portions for Salmonellacompared to the cultural reference method; stainless steel had a lower number in the external study only. The test method provided the final result in 18-30 hours utilizing a fully automated instrument compared to at least 3 days for cultural methods.
Significance: Salmonella enterica spp. can be detected at low levels of contamination in as few as 12 hours of enrichment.