Evaluation of In Vitro Bactericidal Activity of Disinfectants against Major Nosocomial Pathogens

Choi, Sun Ju; Shim, Eun Hee; Kim, Young Moo; lee, Do Hyun; Lee, Chang Gyu; Cheong, Hee Jin; Kim, Woo Joo

Abstract

BACKGROUND
Disinfectants play an important role in preventing nosocomial infection. But the misuse of disinfectants may lead to waste money and decrease the effectiveness of disinfectants by emergence of resistant-bacteria. We studied to evaluate the in vitro bactericidal activity of various disinfectants used in the hospital against major nosocomial pathogens. METHOD: Disinfectants studied were chlorhexidine (0.05%, 0.1 %, 02%, 0.5%, 1%), hibicol 0.5%, alkyl diaminoethyl glycine (0.01 %. 0.05%, 0.1%. 0.5%, 1%), benzalkonium chloride (0, 1%, 0.3%), hydrogen peroxide (1.5%,3%), isopropyl alcohol 70%, potadine iodine(7.5%, 10%), and gentian violet (0.01 %, 0.1%, 1%). Bactericidal activity of disinfectants was assessed against MRSA (methicillin-resistant S. aureus), P. aeruginosa, VRE (vancomycin-resistant enterococci), K. pneumoniae. CNS (coagulase-negative staphylococci) and C albicens. Those microorganisms were obtained from the patients with hospital-acquired infections, In vitro susceptibility was determined using a macrodilution method with various exposure times to several concentrations of disinfectants of 30sec, 1 min, 2 min, 5 min, 15 min and 30 min. RESULT: Microorganism studied were killed after exposure to hibicol 0,5%, isopropyl alcohol 70%, pcradme iodine (7.5%, 10%) within 30sec. 0.05% chlorhexidine needs exposure time above 5 min for bactericidal action. 0.01% alkyl diaminoethyl glycine needs exposure time above 15 min. 0.1% and 0.3% benzalkonium chloride needs exposure time above 1 min. MRSA and P. aeruginosa were killed within 30sec after exposure to gentian violet (GV), but against CNS, 0.01% GV needs exposure time for 15min and 0.1% and 1% GV needs exposure time for 2 min. C. albicans were killed above 1 min. K. pneumoniae was not killed at all. H202 was ineffective for all tested bacteria.
CONCLUSION
The results of this study show most disinfectants used in our hospital demonstrated bactericidal activity against major nosocomial pathogens. In-house diluted, 3% H202 failed to demonstrate killing of any microorganisms tested. The appropriate selection of disinfectants regarding to concentration and exposure time was necessary to inhibit growth of major nosocomial pathogens.