The Biofilm formation ability ofListeria monocytogenesisolated from meat, poultry, fish and processing plant environments is related to serotype and pathogenic profile of the strains

In the present study, the relationships between serotype, pathogenic profile andin vitrobiofilm formation of 106Listeria monocytogenesstrains, having no epidemiological correlation and isolated from different environmental and food sources, were analyzed. The quantitative assessment of thein vitrobiofilm formation was carried out by using a microtiter plate assay with spectrophotometric reading (OD620). The isolates were also submitted to serogrouping using the target geneslmo0737,lmo1118,ORF2819,ORF2110,prs, and to the evaluation of the presence of the following virulence genes:prfA,hlyA,rrn,inlA,inlB,iap,plcA,plcB,actAandmpl, by multiplex PCRs. The 62% of the strains showed weak or moderatein vitroability in biofilm formation, in particular serotypes 1/2b and 4b, frequently associated with sporadic or epidemic listeriosis cases. The 25% of these isolates showed polymorphism for theactAgene, producing a fragment of 268-bp instead of the expected 385-bp. The deletion of nucleotides in this gene seems to be related to enhanced virulence properties among these strains. Strains belonging to serotypes associated with human infections and characterized by pathogenic potential are capable to persist within the processing plants forming biofilm.