What is the Antimicrobial activity of wound and skin cleansers at non-toxic concentrations?

Objective: To compare the antibacterial activities of commercially available skin, wound, and skin/wound cleansers at cell safe (nontoxic) concentrations

Methods:  Saline and 19 commercial cleansers were evaluated for cytotoxic effects on L929 mouse dermal fibroblasts. Cells were exposed to serial 10-fold dilutions of each cleanser until treatment –induced cytotoxicity was comparable to the baseline cytotoxicity of unexposed control fibroblasts. Time-kill kinetics of these test concentrations of cleansers was tested against methicillin resistant S.aureus ATCC 33591.

Results: The experimental design allowed calculation of relative cytotoxicity indexes ranging from 0 to 100,000. Two poloxomer 188 solutions and saline were found to be the least toxic (toxicity index 0); Chlorhexidine gluconate solution (4.0% w/v), polysorbate 20 solution and povidone-iodine (7.5%) most toxic (toxicity index 10,000). At non cytotoxic concentrations pure hypochlorous acid (0.01%) was the most rapidly bactericidal, achieving a 4 log reduction in CFU in less than 60 seconds. A mixture of hypochlorous acid / sodium hypochlorite (in molar ratio 50/50) at pH 7.4 was next at 30 minutes while most of the agents tested required > 24 hours.

Conclusions: Wound healing depends on maintainging bacterial balance while not damaging the viability of the healing tissues. In vitro toxicity indexes provide helpful guidelines for subsequent in vivo evaluations and clinical applications. The study findings suggest that pure hypochlorous acid (0.01%)^e in contrast with many commercially available wound cleansers has rapid bactericidal activity at concentrations that are safe for human cells.