Ethanol

Ethanol has a comprehensive bactericidal and yeasticidal activity at 78–85% within 30 s, whereas some food-associated fungi require at least 10 min. Ethanol has also mycobactericidal activity at ≥70% within 30 s to 5 min depending on the species and ethanol concentration. The antimicrobial effect of ethanol is explained by the non-specific coagulation or denaturation of proteins. No specific cellular defence mechanisms against ethanol have been described. Ethanol >5% may reduce the formation of a developing biofilm. At 40–95%, ethanol usually increases the further formation of an existing biofilm. Biofilm removal by ethanol is usually <50%. Increased MIC values indicating tolerance to ethanol have been reported in some clinical isolates, and their relevance is uncertain. Low ethanol concentrations may reduce the susceptibility to lethal ethanol concentrations in L. monocytogenes and S. cerevisiae. In B. subtilis and E. coli, low ethanol concentrations caused a significant increase in the transfer of mobile genetic elements (resistance genes). No ethanol-resistant isolates have been described with an insufficient efficacy in suspension tests or tests under practical conditions or with a contamination of disinfectants. The overall probability of resistance to ethanol of practical relevance is very low in the absence of biofilm.