Evaluation of Methods for Identifying Poultry Wing Rinses With Salmonella Concentrations Greater Than or Equal to 10 CFU/mL

Abstract

In the United States, the Proposed Regulatory Framework to Reduce Salmonella Illnesses Attributable to Poultry published by the Food Safety and Inspection Service (FSIS) has highlighted the need for simple, rapid methods that identify poultry wing rinse samples harboring Salmonella concentrations ≥10 CFU/mL. One of eight cold-stressed and nutrient-starved Salmonella strains was inoculated into post-chill two-joint poultry wing rinses (48 turkey and 72 chicken) at levels from 0.22 to 3.79 log CFU/mL, and then measured by 3-tube Most Probable Number (MPN), BioMerieux GENE-UP QUANT, Hygiena BAX SalQuant, and novel threshold methods. The MPN lower limit of quantification (LLQ) for Salmonella was −0.96 log CFU/mL. MPN overestimated the inoculated Salmonella level by 0.05 ± 0.35 log CFU/mL. The GENE-UP QUANT Salmonella method (LLQ = 1.00 log CFU/mL) underestimated the inoculated Salmonella level by 0.05 ± 0.51 log CFU/mL. The BAX SalQuant method (LLQ = 0.00 log CFU/mL) underestimated the inoculated Salmonella level by 1.21 ± 0.78 log CFU/mL. Threshold test methods with Poisson probabilities of 0.95 (PiLOT-95), 0.86 (PiLOT-86), 0.63 (PiLOT-63), and 0.50 (PiLOT-50) were developed to identify poultry wing rinses harboring Salmonella levels ≥10 CFU. MPN was 93.1%, accurate for determining if Salmonella levels in poultry wing rinses were ≥10 CFU/mL, but MPN costs and time requirements can be prohibitive for most laboratories. GENE-UP quantification was 86.1% accurate, but the GENE-UP method requires equipment and technical expertise that some food safety laboratories may not possess. BAX quantification had the lowest accuracy; 58.4%. PiLOT threshold test accuracies ranged from 83.2% for PiLOT-50 to 93.1% for PiLOT-86. The PiLOT threshold tests are simple and can be adapted to identify many environmental or food samples containing Salmonella exceeding any user-defined concentration threshold.