Survey for Listeria monocytogenes on ready-to-eat foods from retail establishments in the United States (2010-2013): assessing potential changes of pathogen prevalence and levels in a decade

Authors: Luchansky, John; CHEN, YUHUAN - Food And Drug Administration(FDA); Porto-Fett, Anna; POUILLOT, REGIS - Food And Drug Administration(FDA); Shoyer, Brad; JOHNSON-DERYCKE, RACHEL - Food Safety Inspection Service (FSIS); EBLEN, DENISE - Food Safety Inspection Service (FSIS); SHAW, WILLIAM - Food Safety Inspection Service (FSIS); VAN DOREN, JANE - Food And Drug Administration(FDA); CATLIN, MICHELLE - Food Safety Inspection Service (FSIS); LEE, JEEHYUN - Drexel University; TIKEKAR, ROHAN - Drexel University; GALLAGHER, DANIEL - Virginia Polytechnic Institution & State University; Lindsay, James; ADAMS, ANDREA - Drexel University; AGNELLA, SALLY - Drexel University; AKINGBADE, DARE - Food Safety Inspection Service (FSIS); AYALA, AIMEE - Delaware Valley College; BAKER, ELIZABETH - Drexel University; BARLOW, KRISTI - Food Safety Inspection Service (FSIS); BAUER, NATHAN - Food Safety Inspection Service (FSIS); BENJAMIN, LISA - University Of California; BERRY, KATRINA - Drexel University; Call, Jeffrey; CAMPANO, STEPHEN - Hawkins, Inc; COOK, VICTOR - Food Safety Inspection Service (FSIS); GALLAGHER, DAN - Virginia Tech; GATHERCOLE, LAURA - Food And Drug Administration(FDA); GHAZZI, DEENA - Ursinus College; Govoni, Jessica; HAY, GREGORY - Food And Drug Administration(FDA); HARVEY, CAITLIN - Drexel University; HOELZER, KARIN - Food And Drug Administration(FDA); KANJANAKORN, ALISA - Drexel University; KAUSE, JANELL - Food Safety Inspection Service (FSIS); KHOKHAR, SHEERI - Drexel University; KING, JOHN - Drexel University; KLEIN, VALENTINA - Delaware Valley College; LOPEZ, JOANNA - Food And Drug Administration(FDA); MARTINO, KARINA - Drexel University; MBANDI, EVELYNE - Food Safety Inspection Service (FSIS); MURPHY, MELISSA - Drexel University; NASELLA, JAMES - Drexel University; NGUYEN, TRANG - Drexel University; ORYANG, DAVID - Food And Drug Administration(FDA); Osorio, Manuela; PAPADAKIS, LORI - Food And Drug Administration(FDA); RAJAKUMAR, ALICE - Drexel University; REED, CHINA - Drexel University; SAME, MARY - Food And Drug Administration(FDA); SHANE, LAURA - Delaware Valley College; SPURLINO, CHRISTOPHER - Drexel University; STARKS, HOLLAND - Drexel University; Torrence, Mary; WILLIAMS, LAURIE - Food And Drug Administration(FDA); WADSWORTH, SARAH - Drexel University; WYSZKOWSKI, KIMBERLY - Delaware Valley College; YOO, KELSEY - Virginia Tech; DENNIS, SHERRI - Food And Drug Administration(FDA)

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2017
Publication Date: 4/24/2017
Citation: Luchansky, J.B., Chen, Y., Porto Fett, A.C., Pouillot, R., Shoyer, B.A., Johnson-Derycke, R., Eblen, D.R., Shaw, W.K., Van Doren, J.M., Catlin, M., Lee, J., Tikekar, R., Gallagher, D., Lindsay, J.A., Adams, A., Agnella, S., Akingbade, D., Ayala, A., Baker, E.G., Barlow, K., Bauer, N., Benjamin, L.A., Berry, K., Call, J.E., Campano, S.G., Cook, V., Gallagher, D., Gathercole, L., Ghazzi, D., Govoni, J.A., Hay, G., Harvey, C., Hoelzer, K., Kanjanakorn, A., Kause, J., Khokhar, S., King, J., Klein, V., Lopez, J., Martino, K., Mbandi, E., Murphy, M., Nasella, J., Nguyen, T., Oryang, D., Osoria, M., Papadakis, L., Rajakumar, A., Reed, C., Same, M., Shane, L., Spurlino, C.A., Starks, H.E., Torrence, M.E., Williams, L., Wadsworth, S., Wyszkowski, K., Yoo, K., Dennis, S. 2017. Survey for Listeria monocytogenes on ready-to-eat foods from retail establishments in the United States (2010-2013): assessing potential changes of pathogen prevalence and levels in a decade. Journal of Food Protection. 80:903-921.

Interpretive Summary: Listeria monocytogenes is a food borne pathogen of particular concern to public health because it can be found in or on a variety of both raw and ready-to-eat (RTE) foods. This bacterium is also believed to have a comparatively low infectious dose (e.g., ca. 100 cells) and a very high mortality rate (e.g., 30%), especially for segments of the population that are at elevated risk. Given the widespread occurrence and persistence of this pathogen in our food supply, our group and other researchers have conducted surveys to determine the presence/absence and levels of this pathogen in RTE retail foods. Of note are multi-institutional, large-scale surveys published in the late 1990's and early 2000's that established the prevalence of this pathogen at about 1.8% from among some 70,000 food samples tested. In the present study, over a 100-week period between 2010 and 2013 we sampled some 27,000 RTE foods comprising 18 different food types to determine the true prevalence of the pathogen. In general, the estimated prevalence in food categories such as seafood, diary, produce, meat, eggs, and combination foods (e.g., deli-style salads and sandwiches) purchased from local stores and nations chain stores ranged from 0 to ca. 1%. Our results confirmed that the estimated prevalence of the pathogen was appreciably lower in the early 2010's compared to studies of similar scope and magnitude nearly a decade earlier. The lower prevalence we observed may be due to regulatory and industry efforts over the last 10 years to better manage this pathogen in RTE foods.

Technical Abstract: A multi-year Interagency Listeria monocytogenes Market Basket Survey (Lm MBS) was undertaken for selected categories of refrigerated ready-to eat (RTE) foods purchased at retail in four FoodNet sites in the U.S. Eighteen product types were sampled, including RTE seafood, produce, dairy, meat, eggs, and combination foods. Samples were collected on a weekly basis in large supermarkets and independent grocery stores in California, Maryland, Connecticut, and Georgia for 100 weeks between December 2010 and March 2013. Of the total 27,389 samples, 116 samples tested positive by a PCR assay for L. monocytogenes, and the pathogen was isolated and confirmed from 102 samples. Among the 18 food types, the proportion of positives (i.e., without considering clustering effects) based on recovery of a viable isolate of L. monocytogenes ranged from zero [95%CI: 0.00, 0.18] for soft ripened and semi-soft cheese to 1.07% [95% CI: 0.63, 1.68] for cut vegetables-raw. Across all food types, L. monocytogenes contamination was significantly associated with the state (p<0.05), but not with the manufacturing location (prepackaged vs. deli-packaged in store), the type of store (chain vs. independent), or the season. Pathogen levels in food samples testing positive ranged from ca. <0.03 MPN/g to 4.0 log CFU/g. For smoked seafood, seafood salads, soft ripened and semi-soft cheeses, and deli-type salads without meat, the positive rate is significantly lower (p<0.001) in this survey than that reported a decade ago in comparable surveys in the U.S. Findings from this study show a significant decrease in L. monocytogenes contamination in tested RTE foods over a decade. This trend occurred during a timeframe wherein new regulations and regulatory guidance, as well as improved industry practices related to sanitation and product formulation, were implemented.