title: Prevalence of Listeria monocytogenes in Retail Lightly Pickled Vegetables and Its Successful Control at Processing Plants.
abstract: Incidences of food poisoning traced to nonanimal food products have been increasingly reported. One of these was a recent large outbreak of Shiga toxin-producing Escherichia coli (STEC) O157 infection from the consumption of lightly pickled vegetables, indicating the necessity of imposing hygienic controls during manufacturing. However, little is known about the bacterial contamination levels in these minimally processed vegetables. Here we examined the prevalence of STEC, Salmonella spp., and Listeria monocytogenes in 100 lightly pickled vegetable products manufactured at 55 processing factories. Simultaneously, we also performed quantitative measurements of representative indicator bacteria (total viable counts, coliform counts, and β-glucuronidase-producing E. coli counts). STEC and Salmonella spp. were not detected in any of the samples; L. monocytogenes was detected in 12 samples manufactured at five of the factories. Microbiological surveillance at two factories (two surveys at factory A and three surveys at factory B) between June 2014 and January 2015 determined that the areas predominantly contaminated with L. monocytogenes included the refrigerators and packaging rooms. Genotyping provided further evidence that the contaminants found in these areas were linked to those found in the final products. Taken together, we demonstrated the prevalence of L. monocytogenes in lightly pickled vegetables sold at the retail level. Microbiological surveillance at the manufacturing factories further clarified the sources of the contamination in the retail products. These data indicate the necessity of implementing adequate monitoring programs to minimize health risks attributable to the consumption of these minimally processed vegetables.
authors.affiliation: Division of Bacteriology, Osaka Prefectural Institute of Public Health, Nakamichi 1-3-69, Higashinari-Ku, Osaka 537-0025, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Taguchi
authors.affiliation: Division of Bacteriology, Osaka Prefectural Institute of Public Health, Nakamichi 1-3-69, Higashinari-Ku, Osaka 537-0025, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Kanki
authors.affiliation: Izumisano Public Health Center, Kamikawaraya 583-1, Izumisano, Osaka 598-0001, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Izumisano Public Health Center, Kamikawaraya 583-1, Izumisano, Osaka 598-0001, Japan.
authors.forename: Hideichi
authors.initials: H
authors.lastname: Inamura
authors.affiliation: Kishiwada Public Health Center, Nodamachi 3-13-1, Kishiwada, Osaka 596-0076, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Koganei
authors.affiliation: Food Safety Promotion Office, Environment Health Division, Department of Health Care and Welfare, Shiga Prefecture, Gotenham 13-45, Otsu, Shiga 520-0834, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sano
authors.affiliation: Department of Microbiology, Osaka City Institute of Public Health and Environmental Sciences, Tojo-cho 8-34, Tennoji-ku, Osaka 543-0026, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Division of Biomedical Food Research, National Institute of Health Sciences, Kamiyoga 1-18-1, Setagaya-ku, Tokyo 158-8501, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Asakura
mesh_terms: D015169:Colony Count, Microbial; D005506:Food Contamination; D005516:Food Microbiology; D005838:Genotype; D006801:Humans; D008089:Listeria monocytogenes; D015995:Prevalence; D014675:Vegetables / Q000382:microbiology*
keywords: Lightly pickled vegetable; Listeria monocytogenes; Persistent strain