Comparative sensitivity of 13 species of pathogenic bacteria to seven chemical germicides

Background: The relative resistance of diverse human bacterial pathogens to commonly used germicidal agents has not been established. Methods: We measured by titration the survival of thirteen different bacteria after exposure to glutaraldehyde, formaldehyde, hydrogen peroxide, peracetic acid, cupris ascorbate, sodium hypochlorite, or phenol. Results: Our comparative experiments allowed classification of the organismsʹ survival into four groups: (a) Pseudomonas aeruginosa and Staphylococcus aureus showed the most resistance, (b) Clostridium perfringens, Salmonella typhimurium, Staphylococcus epidermidis, and Escherichia coli O157:H7 showed intermediate resistance, (c) Listeria monocytogenes, Shigella sonnei, and Vibrio parahaemolyticus survived some treatments with chemical agents only in the presence of protecting protein (serum albumin), and (d) Vibrio cholerae, Vibrio vulnificus, Bacillus cereus, and Yersinia enterocolitica did not survive any of the treatments applied. Conclusion: We found species that more frequently survived exposure to germicidal agents were also those most comonly reported in association with hospital infections. Our findings suggest that resistance to disinfectants may be more important than pathogenicity in determining the relative prominence of an organism as an agent responsible for nosocomial infections.