Some virulence genes and biofilm formation capabilities of Listeria monocytogenes isolates from different sources

In this study, it was aimed to determine the biofilm-forming abilities of both clinical and food-borne isolates of Listeria monocytogenes, to investigate the presence of nine different virulence genes, and to consider the current threat status of this agent. A total of 28 isolates, 21 from food and seven from clinical origin, were used in the study. Two different methods, namely “tube adherence” and “microplate” were used to determine the biofilm formation abilities of isolates. For the determination of nine different virulence genes of Listeria monocytogenes (inlA, inlC, inlJ, hylA, luxS, flaA, prfA, inlB, actA), the method of polymerase chain reaction (PCR) was used. As a result, all isolates were found to be able to form a biofilm to varying degrees by both tube and microplate methods. These two methods were similar in terms of their results. All nine different virulence gene regions were detected at various rates in the isolates. Although the genes directly related to biofilm formation for the isolates weren't detected, to form biofilm was observed. The virulence genes detected in clinical origin isolates were proportionally higher than in food-borne isolates (except for flaA and prfA gene regions). It was concluded that bacteria of Listeria monocytogenes continue to form biofilm and carry virulence genes regardless they are from food or clinical origin. Also, food-borne contaminations continue to be a severe threat to human health. So, to prevent listeriosis, cases of both humans and animals should be taken required precautions and all cases should be considered carefully.