In vitro bactericidal and fungicidal activities of commercially available low-irritant hand sanitizers

High-concentration alcohol-based hand rubs (≥60% [v/v]) are strongly recommended to prevent healthcare-associated infections; however, their frequent use can aggravate hand eczema and reduce hand hygiene compliance. Therefore, low-irritant hand sanitizers with reduced alcohol content and alcohol-free formulations have been increasingly adopted in Japanese healthcare settings. Because these products typically contain benzalkonium chloride or chlorhexidine gluconate, along with ingredients that may affect bactericidal performance, this study evaluated the in vitro bactericidal and fungicidal activities of seven low-irritant sanitizers.

Following the ASTM E2315 and guidelines of the Japanese Society for Infection Prevention and Control, testing was performed using four bacterial species (Escherichia coli, Pseudomonas aeruginosa, Enterococcus hirae, and Staphylococcus aureus) and one yeast species (Candida albicans) at contact times of 15 and 30 s. Efficacy was defined as a >5-log reduction in bacteria and >4-log reduction in yeast.

The pH was weakly acidic for products C and D, neutral for products A, B, E, and G, weakly alkaline for product H, and strongly alkaline for product F (pH 12.2). Products A and F met the efficacy criteria against all organisms at 15 s. Product G met the bacterial criteria at 15 s and achieved fungicidal efficacy at 30 s. The other products did not meet the fungicidal criterion, and product C also failed to meet the efficacy criterion against S. aureus.

Overall, efficacy was formulation-dependent and may be influenced by alcohol content, alkalinity, and other additives, in addition to benzalkonium chloride or chlorhexidine gluconate.