Sensitivity, specificity, and predictive values of three Salmonella rapid detection kits using fresh and frozen poultry environmental samples versus those of standard plating

To reduce human exposure to Salmonella spp. in poultry products, broiler ch icken flocks have been tested by culture methods. Since the standard techni ques may take 3 to 5 days, rapid detection methods have been developed. In this study we tested the performance of three rapid tests originally develo ped for food samples by using environmental samples obtained from poultry h ouses. These rapid tests were Reveal, an enzyme-linked immunosorbent assay from Neogen Corp.; BIND, a bacterial ice nucleation detection method from I detek Corp.; and a filter monitor method from Future Medical Technologies, Inc. For the standard culture, brilliant green with novabiocin and xylose-l ysine-tergitol-4 agar were used for presumptive identification, and identit ies were confirmed by using poly-O antisera. Environmental samples were col lected from farms belonging to an integrated poultry company prior to chick placement and 1 week before slaughter. Sensitivities, specificities, and p redictive values with 95% confidence intervals were calculated. Statistical differences were determined by using McNemar's chi square test. The sensit ivities of the different tests were not stable, varying widely between samp le times, and were affected by freezing of the samples. All of the rapid te sts had low sensitivities, which led to many false-negative results. All te sts were able to detect Salmonella spp. at a concentration of 10 CFU/ml in at least one of four trials. The BIND and Reveal tests were simple to use w ith multiple samples and reduced laboratory time by up to 1 day. Based on o ur results, we do not recommend that any of these rapid tests, in their pre sent state of development, be utilized with environmental samples collected with drag swabs.