In-vitro evaluation of bactericidal activity of antiseptics and disinfectants commonly used in healthcare settings

Abstract

Introduction: Healthcare-associated infections are common problems found in healthcare systems in most of the countries. Proper use of antiseptics and disinfectants is useful in reducing the magnitude of such infections. The aim of this study was to evaluate the bactericidal effect of different concentrations of selected antiseptics and disinfectants. Methods: Bactericidal activity of different concentrations of antiseptics and disinfectants; isopropyl alcohol, povidone iodine, chlorhexidine gluconate, sodium hypochlorite, hypertonic saline, peracetic acid and mixture of 2-aminoethanol, dodecyl dimethyl ammonium chloride, potassium carbonate & bis(3-aminopropyl) dodecylamine were evaluated against nine strains of American Type Culture Collections and 11 strains isolated from the hospitals. Bacterial suspensions were prepared equal to 0.5 McFarland turbidity standards and 100 μl of each was mixed with 3 ml of antiseptic/ disinfectant solution. After desired contact time (1 minute, 15 minutes and 24 hours), 20 μl of reaction mixer was transferred into 4 ml of sterile physiological saline, mixed well and 20 μl of solution was evenly spread throughout Muller Hinton agar/ blood agar plates. Growth control was done using 3 ml of distilled water instead of 3 ml of antiseptic/ disinfectant solution. All plates incubated at 35oC ± 2oC for 18 – 24 hours. Colonies were counted and reduction percentage was calculated. Results: All concentrations of isopropyl alcohol, povidone iodine, chorhexidine, sodium hypochlorite, peracetic acid and the mixture of 2-aminoethanol, didecyldimethylammonium chloride, potassium carbonate and bis(3-aminopropyl)dodecylamine showed 100% bactericidal activities against all tested bacterial strains in1-minute contact time. Bactericidal activity of hypertonic saline was varied against tested bacterial strains with higher bactericidal activity against Gram positive organisms than Gram negative organisms. Conclusions: Currently using concentrations of antiseptics and disinfectants evaluated in this study have 100% bactericidal activity other than hypertonic saline.