Ethanol disinfection of plastic-adherent micro-organisms

SummaryThis study investigated the bactericidal effect of ethanol/water (70:30 vol:vol) against plastic-adherent organisms that commonly cause line infections. The experiments were performed in polycarbonate wells and all incubations were at 37 °C. Bacteria in broth were inoculated into wells and incubated (16, 40 and 72 h) before washing to remove non-adherent organisms and exposure to ethanol/water. Wells were then re-incubated with broth to detect surviving bacteria. All organisms incubated for 16 h were killed by 1 h of exposure to 70% ethanol. After incubation for 40 h, 4 h of exposure to ethanol was required to kill two strains of Candida albicans. Likewise, one of three of both Klebsiella pneumoniae and Pseudomonas aeruginosa, incubated for 72 h, showed growth after 1 h of exposure to 70% ethanol but not after 4 h of exposure. These results suggest that in contrast to log phase organisms, which are killed by ethanol/water solutions in seconds, plastic-adherent organisms are more resistant to the bactericidal activity of ethanol.