Objective: To identify environmentally safe, rapidly acting agents for killing spores of Clostridium difficile in the hospital environment.
Design: Three classic disinfectants (2% glutaraldehyde, 1.6% peracetyl ions, and 70% isopropanol) and acidified nitrite were compared for activity against C. difficile spores. Four strains of C. difficile belonging to different serogroups were tested using a dilution-neutralization method according to preliminary European Standard prEN 14347. For peracetyl ions and acidified nitrite, the subjective cleaning effect and the sporicidal activity was also tested in the presence of organic load.
Results: Peracetyl ions were highly sporicidal and yielded a minimum 4 log10 reduction of germinating spores already at short exposure times, independent of organic load conditions. Isopropanol 70% showed low or no inactivation at all exposure times, whereas glutaraldehyde and acidified nitrite each resulted in an increasing inactivation factor (IF) over time, from an IF greater than 1.4 at 5 minutes of exposure time to greater than 4.1 at 30 minutes. Soiling conditions did not influence the effect of acidified nitrite. There was no difference in the IF among the 4 strains tested for any of the investigated agents. Acidified nitrite demonstrated a good subjective cleaning effect and peracetyl ions demonstrated a satisfactory effect.
Conclusions: Cidal activity was shown against C. difficile spores by glutaraldehyde, peracetyl ions, and acidified nitrite. As acidified nitrite and peracetyl ions are considered to be environmentally safe chemicals, these agents seem well suited for the disinfection of C. difficile spores in the hospital environment.