Genetic relatedness among Listeria monocytogenes isolated in foods and food production chain in southern Rio Grande do Sul, Brazil

Listeria monocytogenes is a foodborne bacterial pathogen of great concern to food industry. This is mainly due to its capacity to grow at low temperatures, its wide distribution in the environment and ability to adhere to various surfaces that come into contact with food. The aim of this study was to investigate the clonal relationship among L. monocytogenes isolates. Our purpose was to better understand the diversity of this pathogen in foods and food production chains in southern Rio Grande do Sul (Brazil). Forty four L. monocytogenes strains were characterized by serotyping and PFGE. Six different serotypes were found in the food and food environment (1/2a, 1/2b, 1/2c, 3a, 4b, 4e) and combination of macrorestriction patterns using AscI and ApaI, yielded 29 different pulsotypes. Strains with identical restriction patterns were isolated from foods of different sources and environments at different times. The presence of persistent strains of L. monocytogenes emphasizes the importance of cross-contamination in these food processing environments. It is likely that this occurs mainly due to ineffective cleaning and sanitization procedures, which allow for the survival and adaptation of these strains in the food processing environment, thereby causing persistence and contamination of final products.