Biofilm-producing ability and tolerance to industrial sanitizers in Salmonella spp. isolated from Brazilian poultry processing plants

• All Salmonella strains tested were positive for genes csgD and adrA.
• Biofilms were produced in polystyrene plates, on PU and PP slides.
• Viable cells of biofilms were recovered after the treatment with sanitizers.
• Viable cells were recovered only from polyurethane slides.
• Salmonella spp. biofilm inactivation was better with chlorinated alkaline.

The aims of this study were to analyze the biofilm-producing ability of 98 strains isolated from different surface materials in poultry cutting rooms; to assess the presence of the most important to Salmonella biofilm formation genes adrA and csgD in these strains; and to evaluate the tolerance biofilms formed in polypropylene and polyurethane slides to sanitizers commonly used in the industry. Viable cells were removed from the slides soon after treatment with sanitizers, and then submitted to reincubation for a new count. Only one strain was a strong biofilm-producer in polystyrene; 70% of strains were weak, and 29% were moderate producers. Both genes were found in all strains. There were differences in adhesion to polypropylene and polyurethane, and scanning electron microscopy showed that polyurethane surface was more irregular. No viable cells were recovered in polypropylene slides treated with sanitizers; in polyurethane, reduction in viable cell counts soon after sanitizer treatment was enough to consider that sanitizers were efficient. On the other hand, treatment with peracetic acid was not considered efficient. Results of this study should be considered a food safety warning, due to the importance of the biofilm-producing ability both in vitro and in real poultry processing plants.