Abstract
When harmful bacteria are detected in the final product at a food manufacturing plant, it is necessary to identify and eliminate the source of contamination so that it does not occur again. In the current study, the source of contamination was tracked using core genome multilocus sequence typing (cgMLST) analysis in cases where Escherichia coli was detected in the final product at a food manufacturing plant. cgMLST analysis was performed on 40 strains of E. coli collected from the environment [floor (26 strains), drainage ditch (5 strains), container (4 strains), post-heating production line (1 strain)] and products [final product (3 strains) and intermediate product (1 strain)]. In total, 40 E. coli isolates were classified into 17 genogroups by cgMLST analysis. The 4 E. coli strains isolated from the intermediate and final products were classified into two genogroups (I and II). Certain isolates collected from the environment also belonged to those genogroups, it was possible to estimate the transmission of E. coli in the manufacturing plant. Thus, the dynamics of E. coli in the food manufacturing location were clarified by using cgMLST analysis. In conclusion, our results indicate that cgMLST analysis can be effectively used for hygiene management at food manufacturing locations.
Highlights
Escherichia coli is mainly found in the intestinal tracts of animals [1, 2]; as E. coli presumably adheres to food as a result of fecal contamination, such contamination is widely used as a hygiene index for water and food products [3,4,5]
At the food manufacturing plant examined in this study, E. coli was detected in the final products despite the use of heat treatment, suggesting the possibility of cross-contamination of the product from the line
This study evaluated the usefulness of core genome multilocus sequence typing (cgMLST) analysis, which can discriminate between strains at the clonal level, as a hygiene control method in food manufacturing zones
Summary
Escherichia coli is mainly found in the intestinal tracts of animals [1, 2]; as E. coli presumably adheres to food as a result of fecal contamination, such contamination is widely used as a hygiene index for water and food products [3,4,5]. In Japan, the standard criteria for various processed products include the absence of E. coli and coliform bacteria in the final products [6]. Products that do not meet the standard criteria cannot be shipped to the market; this adversely affects food companies, causing economic loss and hampering the reputation of the companies. To avoid this situation, most food companies routinely conduct microbiological tests, such as wiping inspections of the production lines and sampling inspections. If E. coli is detected in the final.
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