Antibiofilm Effect of Disinfectants against Biofilm-Producing Strains of Salmonella spp. Isolated from Foods of Animal Origin

Abstract

 Introduction: Salmonella spp. are zoonotic bacteria that can infect humans and animals as free-living, planktonic forms and can survive on plants and non-living environments in the form of a sessile community called a biofilm. Salmonella spp. have great importance within the concept of "One Health" as the most important public health problem. If bacteria from foods of animal origin form biofilms on inanimate surfaces, they can survive for a long time on machines and surfaces and be a constant source of food contamination in catering and the food industry.

 Aim: The aim of this paper was to compare the sensitivity to disinfectants (hydrogen peroxide, benzalkonium chloride, and sodium hypochlorite) against biofilm producers among bacteria belonging to the genus Salmonella, which are isolated from foods of animal origin. 

Materials and Methods: We have tested 70 Salmonella strains detected in animal-originated food, which were treated with disinfectants (0.5% sodium hypochlorite and benzalkonium chloride, 3% hydrogen peroxide) for 5 minutes after overnight incubation at 25 ℃ and 37 ℃. 

Results: Biofilm production was optimal at 25 ℃, with 15 (21%) isolates classified as non-producers and 55 (79%) isolates producing biofilm with an average biomass of 0.11. At 37 ℃, 26 isolates (37%) did not form a biofilm, while moderate and weak producers were almost evenly distributed. Room temperature was optimal for biofilm production (p < 0.001) compared to 37 ℃.  When it comes to biofilm treatment, NaOCl was the most effective, while hydrogen peroxide and benzalkonium chloride showed equal effects at both temperatures. 

Conclusion: Although quaternary ammonium disinfectants are most often used for cleaning and disinfecting surfaces, they showed the weakest effect on planktonic strains of Salmonella, as well as on biofilm-producing isolates.