Short communicationFailure of foodborne pathogens to develop resistance to sanitizers following repeated exposure to common sanitizers

The increased focus on food safety hygiene in the home and the food industry has resulted in an increasing use of chemical sanitizers. Whether the increased use of sanitizers will result in emergence of sanitizer-resistant foodborne pathogens has been speculated. Sanitizers that may be used in the home for sanitizing of surfaces or in hand sanitizers were evaluated and included sodium hypochlorite, chlorhexidine digluconate, and benzalkonium chloride. The adaptation of surface-associated and planktonic Escherichia coli O157:H7, Salmonella enterica subsp. enterica serovar Enteritidis, Staphylococcus aureus, Listeria monocytogenes and Pseudomonas aeruginosa to those sanitizers was investigated. In the suspension test, all sanitizers effectively reduced microbial number >5 log units after an exposure of 5 min. In the surface test, generally <3 log unit reduction was achieved when sanitizers were tested at 256 ppm. Repeated exposure of surface-associated bacteria resulted in a significant decrease in log number of cells after the first and second exposure to the sanitizer. Serial subculture of S. Enteritidis in sublethal concentrations of chlorexidine digluconate resulted in a stable decreased susceptibility to the agent, but not resistance. Results of this study suggest that foodborne bacterial pathogens remain susceptible to the sanitizers tested under conditions evaluated in this study.