Resistance and cross-resistance to oxidising agents of bacterial isolates from endoscope washer disinfectors.

Bacteria isolated from washer disinfectors using chlorine dioxide as a high-level disinfectant were exposed to peracetic acid, chlorine dioxide and hydrogen peroxide to investigate their susceptibility and possible bacterial cross-resistance to these highly reactive oxidising biocides. Suspension tests demonstrated that ‘in use’ concentrations were not always effective to provide the required disinfection efficacy within recommended exposure times and in some instances a 60 min exposure was necessary to achieve a reduction in number by a factor of 105. It appears that vegetative Gram-positive isolates can become resistant to oxidising agents in vitro, and that cross-resistance to related compounds can occur. J Hosp Infect (2008), doi:10.1016/j.jhin.2008.04.010.