Prevalence of Listeria monocytogenes in sprouts and vegetable mixtures and salads sold in retail shops in Lublin, eastern Poland - preliminary study.

Introduction: In 2022-2023, examinations were carried out for the presence of a pathogenic bacterium Listeria monocytogenes in ready-to-eat (RTE) vegetable products (sprouts and vegetable mixtures and salads) sold for immediate consumption in retail shops located in Lublin, eastern Poland. The identification of Listeria strains were performed according to the Polish Standard and accomplished with the Microgen Listeria-ID System.

Results: A high prevalence of L. monocytogenes infections was found in the unprocessed sprouts of plants belonging to the cabbage (Brassicaceae) family - kale (30.8%), broccoli (18.8%) and radish (7.1%). The mean prevalence of infections in this family (18.6%) was significantly higher compared to the sprouts of plants belonging to other families, none of which were infected (P<0.05). In the minimally processed RTE mixtures and salads, L. monocytogenes was detected in 6.1% of samples. The presence of following non-pathogenic species of the Listeria genus was also found In the examined RTE products: L. innocua, L. grayi, and L. seeligeri, which occurred both in sprouts and vegetable mixtures and salads in the prevalence of 13.8% and 10.2%, respectively.

Conclusions: The obtained results demonstrate a high prevalence of L. monocytogenes in sprouts, especially those of the cabbage family, which was markedly greater compared to vegetable mixtures. The results suggest a need for continuation of research on the occurrence of L. monocytogenes in the sprouts of plants belonging to the cabbage family. If the results of this study are subsequently confirmed, the application of suitable prevention measures are to be highly recommended.