- Six broad groups were tested - seafood, produce, dairy, meat, eggs, and combination foods)
- Samples were collected weekly at large national chain supermarkets and independent grocery stores between December 2010 and March 2013.
- 27,389 total samples were taken with
- 116 samples tested positive by the BAX PCR system for L. monocytogenes, and the pathogen was isolated and confirmed for 102 samples (0.3%)
- 571 samples that tested positive for Listeria-like organisms
A few takeaways
- Screening samples used a 25 gram sample. If a larger sample size was used, would the percent positive be higher?
- Sampling ended over 4 years ago. If sampling and testing were conduced today, would we expect lower numbers?
- Cut raw vegetables were the highest at 1%., but the scariest is the pre-made salads - seafood salad and deli-type salads (and pre-made sandwiches) since those would be consumed without any preparation and the numbers/gram were generally lower.
- While the percentage of cheese samples that were positive are low, there where some high numbers on those that tested positive.
Journal of Food Protection
http://jfoodprotection.org/doi/abs/10.4315/0362-028X.JFP-16-420?code=fopr-site
Survey for Listeria monocytogenes in and on Ready-to-Eat Foods from Retail Establishments in the United States (2010 through 2013): Assessing Potential Changes of Pathogen Prevalence and Levels in a Decade
John B. Luchansky,1 Yuhuan Chen,2* Anna C. S. Porto-Fett,1 Régis Pouillot,2 Bradley A. Shoyer,1 Rachel Johnson-DeRycke,3† Denise R. Eblen,3† Karin Hoelzer,2‡ William K. Shaw Jr.,3 Jane M. van Doren,2 Michelle Catlin,3 Jeehyun Lee,4§ Rohan Tikekar,4§ Daniel Gallagher,5 James A. Lindsay,1 The Listeria Market Basket Survey Multi-Institutional Team,‖ and Sherri Dennis2
ABSTRACT
A multiyear interagency Listeria monocytogenes Market Basket Survey was undertaken for selected refrigerated ready-to-eat foods purchased at retail in four FoodNet sites in the United States. Food samples from 16 food categories in six broad groups (seafood, produce, dairy, meat, eggs, and combination foods) were collected weekly at large national chain supermarkets and independent grocery stores in California, Maryland, Connecticut, and Georgia for 100 weeks between December 2010 and March 2013. Of the 27,389 total samples, 116 samples tested positive by the BAX PCR system for L. monocytogenes, and the pathogen was isolated and confirmed for 102 samples. Among the 16 food categories, the proportion of positive samples (i.e., without considering clustering effects) based on recovery of a viable isolate of L. monocytogenes ranged from 0.00% (95% confidence interval: 0.00, 0.18) for the category of soft-ripened and semisoft cheese to 1.07% (0.63, 1.68) for raw cut vegetables. Among the 571 samples that tested positive for Listeria-like organisms, the proportion of positive samples ranged from 0.79% (0.45, 1.28) for soft-ripened and semisoft cheese to 4.76% (2.80, 7.51) for fresh crab meat or sushi. Across all 16 categories, L. monocytogenes contamination was significantly associated with the four states (P < 0.05) but not with the packaging location (prepackaged by the manufacturer versus made and/or packaged in the store), the type of store (national chain versus independent), or the season. Among the 102 samples positive for L. monocytogenes, levels ranged from <0.036 most probable number per g to 6.1 log CFU/g. For delicatessen (deli) meats, smoked seafood, seafood salads, soft-ripened and semisoft cheeses, and deli-type salads without meat, the percentage of positive samples was significantly lower (P < 0.001) in this survey than that reported a decade ago based on comparable surveys in the United States. Use of mixed logistic regression models to address clustering effects with regard to the stores revealed that L. monocytogenes prevalence ranged from 0.11% (0.03, 0.34) for sprouts (prepackaged) to 1.01% (0.58, 1.74) for raw cut vegetables (prepackaged).
http://jfoodprotection.org/doi/abs/10.4315/0362-028X.JFP-16-420?code=fopr-site
Survey for Listeria monocytogenes in and on Ready-to-Eat Foods from Retail Establishments in the United States (2010 through 2013): Assessing Potential Changes of Pathogen Prevalence and Levels in a Decade
John B. Luchansky,1 Yuhuan Chen,2* Anna C. S. Porto-Fett,1 Régis Pouillot,2 Bradley A. Shoyer,1 Rachel Johnson-DeRycke,3† Denise R. Eblen,3† Karin Hoelzer,2‡ William K. Shaw Jr.,3 Jane M. van Doren,2 Michelle Catlin,3 Jeehyun Lee,4§ Rohan Tikekar,4§ Daniel Gallagher,5 James A. Lindsay,1 The Listeria Market Basket Survey Multi-Institutional Team,‖ and Sherri Dennis2
ABSTRACT
A multiyear interagency Listeria monocytogenes Market Basket Survey was undertaken for selected refrigerated ready-to-eat foods purchased at retail in four FoodNet sites in the United States. Food samples from 16 food categories in six broad groups (seafood, produce, dairy, meat, eggs, and combination foods) were collected weekly at large national chain supermarkets and independent grocery stores in California, Maryland, Connecticut, and Georgia for 100 weeks between December 2010 and March 2013. Of the 27,389 total samples, 116 samples tested positive by the BAX PCR system for L. monocytogenes, and the pathogen was isolated and confirmed for 102 samples. Among the 16 food categories, the proportion of positive samples (i.e., without considering clustering effects) based on recovery of a viable isolate of L. monocytogenes ranged from 0.00% (95% confidence interval: 0.00, 0.18) for the category of soft-ripened and semisoft cheese to 1.07% (0.63, 1.68) for raw cut vegetables. Among the 571 samples that tested positive for Listeria-like organisms, the proportion of positive samples ranged from 0.79% (0.45, 1.28) for soft-ripened and semisoft cheese to 4.76% (2.80, 7.51) for fresh crab meat or sushi. Across all 16 categories, L. monocytogenes contamination was significantly associated with the four states (P < 0.05) but not with the packaging location (prepackaged by the manufacturer versus made and/or packaged in the store), the type of store (national chain versus independent), or the season. Among the 102 samples positive for L. monocytogenes, levels ranged from <0.036 most probable number per g to 6.1 log CFU/g. For delicatessen (deli) meats, smoked seafood, seafood salads, soft-ripened and semisoft cheeses, and deli-type salads without meat, the percentage of positive samples was significantly lower (P < 0.001) in this survey than that reported a decade ago based on comparable surveys in the United States. Use of mixed logistic regression models to address clustering effects with regard to the stores revealed that L. monocytogenes prevalence ranged from 0.11% (0.03, 0.34) for sprouts (prepackaged) to 1.01% (0.58, 1.74) for raw cut vegetables (prepackaged).
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