title: Various Ready-to-Eat Products from Retail Stores Linked to Occurrence of Diverse Listeria monocytogenes and Listeria spp. Isolates.
abstract: Listeriosis outbreaks have been associated with a variety of foods. This study investigated the prevalence and diversity of Listeria monocytogenes and Listeria spp. in ready-to-eat (RTE) products and evaluated the performance of a rapid detection method, the 3M molecular detection assay for L. monocytogenes (MDA-LM), for detection of L. monocytogenes. Assay results were compared with those obtained using the U.S. Food and Drug Administration standard culture method described in the Bacteriological Analytical Manual. Products (n = 200) were purchased from retail stores: 122 aquatic products, 22 products of animal origin, 18 vegetarian products, 15 deli meat products, 13 salad and vegetable products, 4 desserts, 2 egg-based products, and 4 other products. L. monocytogenes prevalence was comparable with both methods. Overall, 15 (7.5%) of 200 samples were positive for L. monocytogenes: 3% of aquatic products, 1.5% of products of animal origin, 1% of vegetarian products, and 2% of deli meat products. Compared with the standard culture method, the sensitivity, specificity, and the accuracy of the MDA-LM were 86.7% (95% confidence interval, 58.4 to 97.7%), 98.4% (95% confidence interval, 95.0 to 99.6%), and 97.5%, respectively. Using the culture-based method, 18 (9%) of 200 samples were positive for Listeria species other than L. monocytogenes. Listeria isolates from these samples were classified into nine allelic types (ATs). The majority of isolates were classified as ATs 58 and 74, which were identified as L. monocytogenes lineages I and IV, respectively. Listeria innocua and Listeria welshimeri also were represented by isolates of multiple ATs. The MDA-LM is a rapid and reliable technique for detecting L. monocytogenes in various RTE foods. Further study is needed to develop effective control strategies to reduce L. monocytogenes contamination in RTE foods.
authors.affiliation: Department of Food Technology, Prince of Songkla University, Hat Yai, Thailand 90112. kitiya.v@psu.ac.th.
authors.forename: Kitiya
authors.initials: K
authors.lastname: Vongkamjan
authors.affiliation: 3M Food Safety, 3M Thailand Ltd., Asoke-Montri Road, Wattana, Bangkok, Thailand 10110.
authors.forename: Janejira
authors.initials: J
authors.lastname: Fuangpaiboon
authors.affiliation: 3M Asia Pacific Pte Ltd., 1 Yishun Avenue 7, Singapore 768923.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Turner
authors.affiliation: Department of Microbiology, Prince of Songkla University, Hat Yai, Thailand 90112.
authors.forename: Varaporn
authors.initials: V
authors.lastname: Vuddhakul
mesh_terms: D000818:Animals; D044822:Biodiversity; D002417:Cattle; D057140:Fast Foods / Q000191:economics / Q000382:microbiology*; D005506:Food Contamination / Q000032:analysis / Q000191:economics / Q000706:statistics & numerical data; D008087:Listeria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D008089:Listeria monocytogenes / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D008461:Meat Products / Q000382:microbiology; D015995:Prevalence; D014481:United States; D014675:Vegetables / Q000382:microbiology