Effect of low doses of biocides on the susceptibility of Listeria monocytogenes and Salmonella enterica to various antibiotics of clinical importance

The use of subinhibitory concentrations biocides in food processing environments requires special attention because it is related to potential increases antibiotic resistance. In this study, we determined the effect exposure low doses four (sodium hypochlorite, SHY; benzalkonium chloride, BZK; peracetic acid, PAA; trisodium phosphate, TSP) on resistance 10 antibiotics and hydrophobicity cellular surface a strain Listeria monocytogenes serotype 1/2 b (LM) Salmonella enterica Agona (SA), both meat origin. cultures were exposed at 37 °C tryptone soya broth increasing biocides, starting with half minimum inhibitory concentration (MIC/2) incrementing by 1.5 times until growth was no longer observed, calculating MIC before (control cultures) after exposure. After TSP, LM able grow presence biocide 2.53 higher than unexposed cultures. No adaptation observed for SHY, BZK or PAA. SE demonstrated (it tolerated 1.13 unadapted strain) PAA (2.53 times). presented increased (from susceptibility reduced susceptibility, from resistance, resistance) erythromycin (strains BZK, TSP), chloramphenicol (all compounds), tetracycline (BZK) fosfomycin compounds). Regarding SA, its gentamicin compounds) enrofloxacin (BZK, increased. cell (determined through microbial adhesion solvents -MATS- test) (LM TSP; SA BZK) decreased (SA PAA) contact biocides. These findings suggest that can contribute increase bacterial antibiotics, addition modifying surface, which capacity bacteria form biofilm.