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.
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.
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.
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.