In-vitro Bactericidal Kinetics of Chlorhexidine Gluconate Disinfectant/ Antiseptic Formulations Containing Different Additives

Abstract

Chlorhexidine gluconate(CHG) is a popular disinfectant/antiseptic which is often formulated with additives. We investigated the effect of additives type on the in vitro bactericidal kinetics of CHG in three commercially available formulations: Hibiscrub^®, Savlon^® and Purit^® commonly used as household and hospital disinfectants/antiseptics. The bactericidal kinetics of the products was determined by time-survival curve method using Pseudomonas aeruginosa NCTC 6750 and Staphylococcus aureus NCTC 6571 as model organisms. Best-fit rate constant and half-life was computed by exponential decay curve-fitting. Half-life was; 76.5, 65.5, 66 and 74 (min) for Control solution, Hibiscrub^®, Savlon^® and Purit^®respectively, against Ps. aeruginosa. The corresponding values obtained against Staph. aureus are 51.0, 61.7, 29.3, and 49.0 (min) (95% CI). Presence of alcohol (e.g. Hibiscrub^® and Savlon^®) caused an insignificant increase in the rate of killing of Ps. aeruginosa relative to preparations that are devoid of alcohol. (p>0.05, 1-way ANOVA). Toward Staphylococcus aureus, the combined effect of cetrimide and alcohol (e.g. Savlon^®) is higher than any enhancement due to combination of alcohol and surfactant (e.g. Hibiscrub). Savlon^® show a significantly higher bactericidal effect of all the preparations (P<0.0001, 1-way ANOVA). The choice of additives in the formulation of chlorhexidine antiseptic solutions significantly alters the kinetics and overall bactericidal effect of CHG towards Staphylococcus aureus but not Pseudomonas areruginosa.

Keywords: Chlorhexidine gluconate, Savlon, Hibiscrub, Purit, bactericidal kinetics