Association between antimicrobial resistance and biofilm forming ability of Salmonella enterica serotypes from commercial broiler farms in Brazil.

1. This study determined the antimicrobial resistance profile and the biofilm-forming ability of Salmonella enterica strains isolated from commercial broiler houses over a three-year period in southern Brazil.2. Of the 720 drag swabs analysed, 37 (5%) tested positive for non-typhoidal Salmonella spp. and S. Heidelberg was the most frequent serovar.3. Among the antimicrobial resistant strains (83.8%; 31/37), resistance was most common to tetracycline, ampicillin and nalidixic acid. Multidrug resistance was found in 65% (24/37) of the isolates, with a large proportion of multidrug resistant S. Heidelberg strains (81%; 13/16).4. In total, 65% (24/37) of the isolates showed the ability to produce biofilm and multiple antimicrobial resistance was negatively correlated with biofilm formation.5. Strains susceptible to all tested antimicrobials tended to form stronger biofilms than multidrug resistant ones. This suggested that Salmonella spp. with less antimicrobial resistance depend more on the protection provided by biofilm to survive in the farm environment.