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.