P3-184 Evaluation of Several Elements in the Environmental Sampling of Listeria spp. from Stainless Steel Surface

Wednesday, July 12, 2017
Exhibit Hall (Tampa Convention Center)
Ishani Sheth , U.S. Food and Drug Administration , College Park , MD
Fengmin Li , U.S. Food and Drug Administration , College Park , MD
Hee jin Kwon , U.S. Food and Drug Administration , College Park , MD
Antonie De Jesus , U.S. Food and Drug Administration , College Park , MD
Thomas Hammack , U.S. Food and Drug Administration , College Park , MD
Karen Jinneman , Food and Drug Administration , Bothell , WA
Yi Chen , U.S. Food and Drug Administration , College Park , MD
Introduction: Listeria monocytogenes causes severe foodborne illness,listeriosis, which primarily affects pregnant women, newborns, elderly, and adults with weakened immune systems and has a case-fatality rate of around 20%. Currently, there are no validated devices and methods for environmental testing of this pathogen by FDA.

Purpose: This project was focused on the evaluation of several elements in the environmental sampling for Listeria spp.: sampling device, storage time after sampling, volume of enrichment broth.

Methods: Listeria monocytogenes was cultured overnight in Brain Heart Infusion (BHI) broth, diluted to proper concentrations, and then dried at room temperature overnight on stainless steel surface. The evaluation followed AOAC microbial method validation guidelines, comparing fractional positive results generated by each variable. The method described in FDA’s Bacteriological Analytical Manual (BAM) was followed in the whole process. Different materials of swabs (cotton, polyester, and polyurethane) and sponges (cellulose and polyurethane) used for collecting L. monocytogenes were compared. After sampling, three storage conditions of the samples were compared: 2 hours at room temperature, 24 h at 4°C, 48 h at 4°C. Two different enrichment volumes were evaluated: 90 ml and 225 ml.

Results: All experiments generated fractional positive results required by the AOAC guidelines. The 3 storage conditions after sampling (2 hours at room temperature, 24 h and 48 hours at 4°C) generated statistically equivalent results. The two enrichment volumes (90ml and 225ml), also, generated statistically equivalent results. Different materials of swabs and sponges generated statistically equivalent results as well. Statistical analyses were performed by probability of detection (POD) analysis according to AOAC guidelines, as well as Fisher’s Exact method.

Significance: This study contributed information that can be used to develop and optimize a complete procedure for environmental sampling of Listeria spp.