Listeria monocytogenes in vegetables minimally processed

The demand of vegetables minimally processed (ready-to-use) has increased partly due to the frequent use of the food services, where the salads are always included in the daily menus. The use of new technologies for processing and packaging has made possible to obtain a product ready to serve. Nevertheless the associated risk of the presence of emergent pathogens, such as Listeria monocytogenes seems to be involved. The aim of this work was to assess the microbiological quality of this kind of food. 120 samples of vegetables minimally processed ready-to-use were analyzed for their content of aerobic mesophilic bacteria, total and fecal coliforms and E. coli, and the presence of Shigella spp. Vibrio cholerae and Listeria monocytogenes. The TECRA UNIQUE LISTERIA, the BCM Listeria monocytogenes and the API LISTERIA systems, and the methods of molecular detection AccuProbe and GENE-TRAK were used for isolation and identification. E. coli was detected in approximately 30.3% of the vegetables used in this study. The genus Listeria was evidenced in 25% of the samples; 30% corresponded to L. monocytogenes. Shigella spp and Vibrio cholerae were not isolated. The findings of this study suggest the need of the microbiological control of the vegetables minimally processed ready-to-use to assure their quality and safety.