title: Interlaboratory Validation for a Real-Time PCR Salmonella Detection Method Using the ABI 7500 FAST Real-Time PCR System.
abstract: Sixteen FERN (Food Emergency Response Network) member laboratories collaborated in this study to verify extension of the real-time PCR Salmonella detection method originally designed for the single-tube Cepheid SmartCycler II and validated against the Salmonella method of the U. S. Food and Drug Administration Bacteriological Analytical Manual to the Applied Biosystems (ABI) 7500 FAST Real-Time PCR system multiwell plate platform. Four foods were selected for this study: chili powder, soft cheese, fish, and tomatoes; these foods represent products that are commonly analyzed for the presence of Salmonella for regulatory purposes. Each food consisted of six uninoculated control samples, six samples inoculated with low Salmonella levels (target 1 to 5 CFU/25 g), and six samples inoculated with high levels (target 10 to 50 CFU/25 g). All samples were tested for Salmonella using the 24-h quantitative PCR (qPCR) method for detecting Salmonella, which utilizes modified buffered peptone water as the sole enrichment medium and an internal control for the qPCR. Each of these 18 samples was individually analyzed for Salmonella by the collaborating laboratories using both the ABI 7500 FAST system (alternative method) and the SmartCycler II system (reference method). Statistical analysis of the data revealed no significant difference (P ≥ 0.05) between these two qPCR platforms except for the chili powder samples. The differences noted with chili powder (P = 0.0455) were attributed to the enhanced sensitivity of the ABI 7500 FAST system compared with the SmartCycler II system. The detection limit of both qPCR methods was 0.02 to 0.15 CFU/g. These results provide a solid basis for extending the 24-h qPCR Salmonella method to the ABI 7500 FAST system for high-throughput detection of Salmonella in foods.
authors.affiliation: U.S. Food and Drug Administration, Office of Regulatory Affairs, Pacific Regional Laboratory Southwest, 19701 Fairchild, Irvine, California 92612, USA.
authors.forename: Chorng-Ming
authors.initials: CM
authors.lastname: Cheng
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5100 Paint Branch Parkway, College Park, Maryland 20740, USA.
authors.forename: Tara
authors.initials: T
authors.lastname: Doran
authors.affiliation: U.S. Food and Drug Administration, Office of Regulatory Affairs, Office of Regulatory Science, 12420 Parklawn Drive, Rockville, Maryland 20857, USA.
authors.forename: Wen
authors.initials: W
authors.lastname: Lin
authors.affiliation: U.S. Food and Drug Administration, Office of Regulatory Affairs, Pacific Regional Laboratory Southwest, 19701 Fairchild, Irvine, California 92612, USA. kai-shun.chen@fda.hhs.gov.
authors.forename: Kai-Shun
authors.initials: KS
authors.lastname: Chen
authors.affiliation: U.S. Food and Drug Administration, Office of Regulatory Affairs, Pacific Regional Laboratory Southwest, 19701 Fairchild, Irvine, California 92612, USA.
authors.forename: Donna
authors.initials: D
authors.lastname: Williams-Hill
authors.affiliation: U.S. Food and Drug Administration, Office of Regulatory Affairs, Office of Regulatory Science, 12420 Parklawn Drive, Rockville, Maryland 20857, USA.
authors.forename: Ruiqing
authors.initials: R
authors.lastname: Pamboukian
mesh_terms: D000818:Animals; D004269:DNA, Bacterial / Q000032:analysis*; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology / Q000379:methods*; D059022:Food Safety; D007753:Laboratories; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D015203:Reproducibility of Results; D012475:Salmonella / Q000235:genetics* / Q000302:isolation & purification; D019779:Salmonella enterica; D014481:United States
chemical_list: D004269:DNA, Bacterial