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P3-171 Relative Effectiveness of Lactose Broth and Selected Buffered Preenrichment Media for the Detection of Salmonella in Artificially Contaminated Casein-based Powdered Infant Formula

Wednesday, July 12, 2017
Exhibit Hall (Tampa Convention Center)
Andrew Jacobson , U.S. Food and Drug Administration , College Park , MD
Hua Wang , U.S. Food and Drug Administration , College Park , MD
James Smiley , U.S. Food and Drug Administration , College Park , MD
Melanie Butler , U.S. Food and Drug Administration , College Park , MD
Thomas Hammack , U.S. Food and Drug Administration , College Park , MD
Introduction: Lactose Broth (LB) is the default preenrichment medium for the BAM Salmonella culture method, however, buffered media have been demonstrated to be more effective than LB for detection of Salmonella in high microbial load foods (p < 0.05).  The relative effectiveness of LB and buffered preenrichments for the detection of Salmonella in low moisture/low microbial foods is unknown.

Purpose: Compare LB and buffered preenrichments for detection of Salmonella in casein based powdered infant formula (PIF).

Methods: Artificially contaminated test portions of casein based PIF were analyzed using LB, Universal Preenrichment Broth (UPB), Buffered Peptone Water (BPW), and modified Buffered Peptone Water (mBPW) in each experimental trial.  Pairwise comparisons of results from the analysis of contaminated PIF, analyzed using the 4 different preenrichment media, were evaluated using chi-square 2-tailed F-test statistical analysis (p < 0.05).

Results: Ten test portions were identified as positive for S. Enteritidis with LB; a value higher than those of 2, 1, and 0 for UPB, BPW, and mBPW, respectively (p < 0.05).  LB was also statistically more effective than UPB and mBPW for the detection of S. Anatum in casein based PIF (p < 0.05), however, there was no statistical difference (p > 0.05) in the recovery of S. Anatum from PIF, between LB and BPW, although LB was arithmetically superior to BPW.  The number of S. Anatum –positive test portions for LB, UPB, BPW, and mBPW were 20, 13, 15, and 13, respectively.

Significance: LB was more effective than UPB, BPW, and mBPW for the detection of Salmonella in casein based PIF (p < 0.05). 

Back to: Poster Session 3 – Low-water Activity Foods, Packaging, Produce, Microbial Food Spoilage, Antimicrobials, Laboratory and Detection Methods, Water
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