Assessing the efficacy of some commercially available disinfectants and antiseptics

Abstract

Disinfectants and antiseptics are chemical agents that are used to control microorganisms. The objectives of this study were to assess the efficacy of some selected disinfectants/antiseptics at the manufacturer-recommended dilution (MRD) and to compare the efficacy of each product at serial concentrations of MRD. Commercially available disinfectants/antiseptics containing benzalkonium chloride (A), sodium hypochlorite (B), chlorinated phenol (C) and phenol (D), were used in this study. Sterile filter-paper discs were dipped separately in different concentrations of each product ranging from the MRD to its serial concentrations. The discs were then incubated on agar plates pre-spreaded with Staphylococcus aureus cultures. Mean diameters of inhibitory zones (ZI) were measured and statistically analyzed for differences with different products. The efficacy of each disinfectant/antiseptic was assessed according to (ZI). Product D showed the highest efficacy whereas product A showed the least efficacy at the MRD. There was no difference in the efficacy of MRD, and its two-fold increase, with product A. In contrast, products B and C showed an increase in the efficacy (p<0.01) with each two-fold increase in the product concentration starting from the MRD. With reference to product D, no difference was observed with the efficacy of MRD and its two-fold increase. Further increase of product concentration (from two-fold to four-fold) showed a decrease in efficacy (p<0.01). In conclusion, all disinfectant/antiseptic products of this study were effective at the MRD. However, the degree of efficacy was different (p<0.01) among products. Certain products (A & D) showed no increase in efficacy (p>0.01) at two-fold increase of MRD but showed increase in the efficacy (p<0.01) at higher concentrations.