LAUSR

Background Monovalent copper compounds have high antiviral and antibacterial activity. Unlike divalent copper compounds, monovalent copper compounds can generate hydroxyl radical which causes oxidative damage to microorganisms. However, the antibacterial activity of monovalent copper compounds against antibiotic-resistant bacteria is not clear. The objective of this study is to evaluate the sustained antibacterial activity of alcohol disinfectant containing monovalent copper compound against antibiotic-resistant bacteria and to compare its antibacterial activity with those of conventional disinfectants. Methods Monovalent copper compound dispersed in 70% ethanol (Ethanol/monovalent copper) was applied on stainless plate by swabbing with cotton fabric. Ethanol (70%), sodium hypochlorite (5000 ppm), and benzalkonium chloride (0.2%) were also applied for comparison. After each disinfectant was dried, each bacterial suspension of antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Acinetobacter baumannii (MDRA), was dropped onto the stainless plate sample. Viable bacteria were evaluated at 1 and 3 hours after each bacterial suspension was applied. Results As compared to the untreated stainless plate, the stainless plates treated with Ethanol/monovalent copper, ethanol, sodium hypochlorite, and benzarconium chloride showed log reductions in the average number of CFUs, 1.08, -0.10, -0.56, and 0.83 log10 at 1 hour contact, >4.01, 0.08, -0.86, and 1.63 log10 at 3 hour contact for MRSA, and >4.86, -0.16, -0.08, and 3.61 log10 at 1 hour contact, >5.14, -0.04, -0.07, and 4.28 log10 at 3 hour contact for MDRA, respectively. Conclusions This study demonstrated that ethanol/monovalent copper have sustained antibacterial activity against MRSA and MDRA even after drying. The antibacterial activity is also higher than a quaternary ammonium salt, benzalkonium chloride which is widely used in healthcare settings. These study findings suggest that monovalent copper compounds serve as a continuously active disinfectant against antibiotic-resistant bacteria in the healthcare environment.