INVESTIGATION OF BIOFILM FORMATION AND ITS ASSOCIATION WITH BIOFILM ASSOCIATED FACTORS OF FOOD-RELATED METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS STRAINS

Microbial biofilm formed on food contact surfaces can lead to significant hygiene and food safety issues. Both methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA and MRSA) have the ability to form biofilms on various food industry surfaces (Mirani et al., 2013). The aim of this study, was to investigated the relationship between biofilm associated factors and the ability of food-derived MRSA strains to form biofilm. Twentytwo MRSA strains and 3 reference strains (S.aureus ATCC 35556, S. aureus ATCC 12600 and S. epidermidis ATCC 12228) were tested for the detection of some genetic markers associated to the biofilm production, by PCR (Shopsin et al., 2003; Graber et al., 2009); furthermore, the strains were tested for the biofilm production on polystyrene and stainless steel using a previously described method (Di Ciccio et al., 2015). Majority of MRSA isolates (90%) showed similar distribution of adhesion genes (icaA, icaD, cna, fnbA and fnbB), toxin genes (hla and hlb), and staphylococcal regulators (sarA). Majority of biofilm producers isolates (66.7%) were found to carry agr type III whereas most of (87.5%) of the biofilm negative isolates were found to carry agr type I. All MRSA strains were found icaA, icaD, hla positive and fnbB negative. Biofilm formation was observed in the 27.2% of the isolates, of which two strains formed strong biofilms, two moderate biofilms and two formed weak biofilms. The biofilm formation by MRSA strains occurred preferentially on polystyrene (27.2%) compared to stainless steel (9%). In conclusion, this study underline the ability of some genotypes of food related MRSA strains to form biofilm on surfaces largely used in the food industry and the need of carefully control their spread for preventing food safety concern.