Sensitivity of Escherichia coli 0157:117 to several disinfectants and heat

We evaluated the bactericidal activity of disinfectants and hot water against 10 Escherichia coli (E. coli) O157:H7 strains that were isolated from feces of patients with enterohemorrhagic E. coli infection and showed different DNA patterns. After exposure to 0.1% benzalkonium chloride, 0.1% chlorhexidine gluconate containing a nonionic surfactant, and 80% v/v ethanol, 99.99% of viable bacterial cells were killed at 20°C within 15 sec irrespective of the presence or absence of 0.1% albumin. After exposure to 0.1% alkyldiaminoethyl glycine, 99.99% of viable cells were killed at 20°C within 15 sec in the absence of albumin and within 30 sec in the presence of albumin. After exposure to 0.01% (100 ppm) sodium hypochlorite, 99.99% of viable cells were killed at 20°C within 15 sec in the absence of a lbumin while only a few cells were killed at 20°C even after 5-min exposure in the presence of 0.1% albumin. After exposure to 0.1% chlorhexidine gluconate containing no surfactant, 99.99% of the bacterial cells were killed within 5 min in the absence of albumin while 99.99% killing could not be achieved within 5 min in the presence of 0.1% albumin. On the other hand, after exposure to hot water, 99.99% of the bacterial cells were killed within 15 sec at 70°C, within 1 min at 65°C, and within 5 min at 60°C. These results suggest that benzalkonium chloride, chlorhexidine gluconate containing a nonionic surfactant, ethanol, and hot water at 70°C or more are effective for disinfection E. coli O157:H7 at hospitals.