Detection of Salmonella cells within 24 to 26 hours in poultry samples with the polymerase chain reaction BAX system

Abstract

BAX, a commercial polymerase chain reaction-based system, was evaluated to determine the efficacy of the system with different concentrations of Salmonella cells in mixed cultures and compared to conventional methods for detection of inoculated Salmonella cells from poultry samples. When present in enrichment broths at levels of 10(5), 10(4), and 10(3) CFU/ml, Salmonella cells were detected in 100, 93, and 41% of samples, respectively. Salmonella cells were detected in 23 of 150 (15%) processed chicken rinse samples with the BAX system compared to 18 of 150 (12%) samples with conventional methods. Salmonella cells were detected in 28 of 50 (56%) ground turkey samples with the BAX system compared to 25 of 50 (50%) samples with conventional methods. Overall there was a 97% method agreement. One false-negative and two false-positive results were obtained with the BAX. Band sizes and intensity of the polymerase chain reaction product were shown to be correlated with estimated numbers of Salmonella CFU present in the enriched and inoculated samples. The assay was able to detect 10(4) Salmonella CFU/ml of enrichment medium, which allows consistent detection of Salmonella cells within 24 to 26 h. The high degree of sensitivity and specificity of the BAX system make it a reliable alternative to conventional bacterial cultural methods.