Introduction: Cattle have been identified as a major reservoir of pathogenic serotypes of Escherichia coli (specifically O157) and foods of bovine origin, including beef and dairy products, as well as plant products have been implicated in numerous outbreaks of infection worldwide. Reliable enrichment and detection systems are necessary to monitor foodstuffs (including rinse waters) for these pathogens to ensure that safe food is being supplied to the consumer.
Purpose: The aim of the study is to evaluate the performance of the RapidChek® E. coli O157 test system against the ISO reference method (NF EN ISO 16654:2001) for the detection of E. coli O157 in meat products, dairy products, and plant products.
Methods: A method comparison study was conducted to determine accuracy, specificity, sensitivity and relative detection level. One hundred ninety-eight (198) samples were analyzed by both methods. Selectivity was evaluated by testing fifty (50) target microorganisms and thirty (30) non-target microorganisms.
Results: The test system demonstrated 85% relative accuracy. The relative sensitivity of the method was 85% and 92% for 8 and 24 hours respectively. The relative specificity was 85% and 74% for 8 and 24 hours, respectively. The relative level of detection of the test method varies from 0.6 to 1.0 CFU/25 g while the limit of detection of the reference method varies from 0.5 to 0.9 CFU/25g. The selectivity of the method was satisfactory.
Significance: The target pathogen can be detected at very low levels of contamination in as few as 8 hours with the test system. Results obtained after 24 hours of incubation of the test system enrichment broth show superior results as compared to the reference method. Confirmation of a positive result can be accomplished in as little as 2 days with the test method versus 3 to 4 days with the reference method.