GENOSEROTYPING OF LISTERIA MONOCYTOGENES STRAINS ORIGINATING FROM MEAT PRODUCTS AND MEAT PROCESSING ENVIRONMENTS

Abstract

Background. Listeria monocytogenes is a foodborne human pathogen and a causative factor of listeriosis, which is an illness with a high mortality rate. Serotyping is a method for differentiating L. monocytogenes isolates based on unique combinations of somatic (O) and flagellar (H) antigens on the surface of their cells. Standard serotyping involves agglutination methods, which require using antisera. However, there are also genoserotyping methods which allow to categorise L. monocytogenes isolates into particular groups of serotypes (referred to as serogroups) based on genetic analyses. Differentiating L. monocytogenes isolates is an important issue in terms of food safety, surveillance and traceability of contamination sources. In this work, we present results of the genoserotyping of 153 L. monocytogenes isolates originating from meat products and meat processing environments at Polish processing plants. Two protocols were used for genoserotyping analyses: the first one allows to differentiate between four most common serotypes (1/2a, 1/2b, 1/2c and 4b) and the second one allows to distinguish hipervirulent serovar 4h from other serotypes. Results and conclusion. Results achieved using both methods were consistent and all isolates were categorised into corresponding serogroups within the two methodologies. Most of the isolates (73.9 %) were characterised as members of the IIa serogroup (representing the 1/2a, 3a serovars). The IVb (4b, 4d, 4e) serogroup was the second most common (and comprised 18.3 % of isolates), followed by IIb (1/2b, 3b, 7) and IIc (1/2c, 3c), however, the last two groups were equally numerous (and each of them comprised 3.9 % of all isolates). None of the collected isolates belonged to the serogroup representing the 4a, 4c, 4ab and 4h serotypes.