USE OF A MICRODILUTION METHOD FOR EVALUAT ING THE BACTERICIDAL ACTIVITY OF 5 DISINFECTANTS ON 108 HOSPITAL STRAINS

The authors studied 5 disinfectants containing aldehyde and quaternary ammonium against 108 hospital strains. The minimal bactericidal activ ities (MBC) were determined with a microdilution method and the diluti on-neutralization method (AFNOR T 72-150). The microdilution method re sults were validated using the MBCs of four reference strains tested w ith the dilution-neutralization method (AFNOR T 72-150). 3 disinfectan ts proved to be valuable. 1 disinfectant was valuable but with a MBC t oward all bacteria only a dilution away from the dilution of use. 1 di sinfectant was determined as unsatisfactory as 9.5 p. cent of all stra ins proved resistant toward it. All disinfectants matched AFNOR standa rds; but those specifications did not match toward hospital strains. S uch an evaluation using a simple and reliable method should be of use.