Fiber optic and light scattering sensors: Complimentary approaches to rapid detection of Salmonella enterica in food samples

Salmonella-related foodborne infections present a major public health problem worldwide despite more stringent regulations. Salmonella enterica serovars Enteritidis and Typhimurium are the two most frequent causes of poultry related outbreaks; therefore, their rapid and accurate detection would improve Salmonella control at the farm, processing plant, and at retail. In this study, we investigated if a fiber optic immunosensor and light scattering sensor, BARDOT (bacterial rapid detection using optical scattering technology) could facilitate the detection of these two serovars in naturally contaminated poultry (n = 50). The fiber optic sensor with a detection limit of 10(3) CPU/ml identified S. enterica in selective enrichment broth in less than 12 h. The colonies (1.0 +/- 0.2 mm) produced by plating the enriched samples on selective XLT4 agar for 13-15 h were scanned using BARDOT and S. enterica was identified after matching individual colony scatter patterns to the scatter image library with a sample-to-answer time of about 24 h. Both sensors identified 4 positive samples (8%), which corresponded to the results of the USDA-FSIS protocol, PCR, and lateral flow immunoassays. The colony scatter patterns identified all natural isolates as S. Enteritidis, which was further verified by serovar-specific PCR. The sensors used individually or in combination demonstrate potential for accurate and rapid detection of S. enterica in poultry. (C) 2015 Elsevier Ltd. All rights reserved.