Detection of salmonella by flow-through immunocapture real-time PCR in selected foods within 8 hours

J Food Prot. 2007 Apr;70(4):1002-6. doi: 10.4315/0362-028x-70.4.1002.

Abstract

This study investigated flow-through immunocapture (FTI), using the Pathatrix device, followed by plating on xylose lysine desoxycholate (XLD) agar (FTI-XLD) or analysis by real-time PCR (FTI-PCR) for the detection of Salmonella on smooth tomato surfaces and in potato salad and ground beef within 8 h. Food samples were inoculated with an appropriate dilution of a five-serovar Salmonella cocktail and enriched for 5 h. Following enrichment, samples were analyzed by the FTI-XLD and FTI-PCR methods. Food samples were also analyzed by a modified U.S. Food and Drug Administration Bacteriological Analytical Manual (BAM) Salmonella culture method for comparison. Salmonella inoculated at 10(0) CFU per tomato or 10(0) CFU/25 g was detected by the FTI-XLD method in 6, 8, and 4 of 10 samples for tomatoes, potato salad, and ground beef, respectively. Salmonella inoculated at 10(0) CFU per tomato or 10(0) CFU/25 g was detected by the FTI-PCR method in 8, 9, and 9 of 10 samples for tomatoes, potato salad, and ground beef, respectively. The FTI-PCR method achieved significantly higher (P < 0.05) detection of Salmonella on tomatoes, whereas the FTI-XLD method achieved significantly lower (P < 0.05) detection of Salmonella in ground beef when compared with the modified BAM Salmonella culture method; however, all other comparisons to the modified BAM method were not significantly different. The FTI-XLD method demonstrated the ability to isolate presumptive Salmonella colonies up to 48 hfaster than did the modified BAM Salmonella culture method.

MeSH terms

  • Bacteriological Techniques / methods*
  • Colony Count, Microbial
  • DNA, Bacterial / analysis*
  • Food Contamination / analysis*
  • Food Microbiology
  • Meat Products / microbiology
  • Polymerase Chain Reaction / methods*
  • Reproducibility of Results
  • Salmonella / isolation & purification*
  • Sensitivity and Specificity
  • Solanum lycopersicum / microbiology
  • Solanum tuberosum / microbiology
  • Time Factors

Substances

  • DNA, Bacterial