SUSCEPTIBILITY OF VANCOMYCIN-RESISTANT ENTEROCOCCI TO ENVIRONMENTAL DISINFECTANTS

OBJECTIVE: To determine the susceptibilities of vancomycin-resistant a nd -sensitive enterococci (VRE and VSE) to various concentrations of c ommonly used, commercial, hospital-grade disinfectants. DESIGN: A micr obial suspension test using inocula of 10(8) cells per mL in a disinfe ctant test dilution was used to determine inactivation kinetics of the test strains. In each test, 1-mL aliquots were removed from the cell- disinfectant mixtures at 15 and 30 seconds and then at 1-minute interv als for 5 minutes and neutralized. Appropriate serial dilutions were p lated on agar medium for enumeration of survivors. RESULTS: VRE and VS E challenge inocula (in the absence of any additional protein or serum challenge) were below the limit of detection (5 colony-forming units/ mL) after 15 seconds' exposure to the manufacturers' suggested use-dil utions of quaternary ammonium, phenolic, or iodophor germicidal deterg ents. In subsequent tests, when the disinfectants were diluted far bey ond the recommended use-dilutions (extended dilution), no differences were demonstrated between the susceptibilities of VRE and VSE. CONCLUS IONS: VRE and VSE are sensitive to a spectrum of commonly used environ mental disinfectants and have parallel inactivation rates when challen ged with extended dilutions of these products. Our findings did not de monstrate a relationship between antibiotic and germicide resistance. Routine disinfection and housekeeping protocols presently used in hosp itals need not be altered due to concerns about the potential for envi ronmentally mediated transmission of antibiotic-resistant microorganis ms.