Does Extreme Wettability Matter: The Effect of Copper Wettability on Infection Spread through Hospital Surfaces

Abstract

One of the reasons for the widespread occurrence of hospital-acquired infections is the ability of microorganisms to survive for extended periods on the indoor surfaces of healthcare facilities. Although the antibacterial properties of copper are well-known and have already been used in medical practice, there is still a lack of research on how extreme wettability of copper-based materials by biological fluids can affect the reduction of surface contamination and, consequently, the spread of hospital-acquired infections, particularly in healthcare settings. This study aims to compare the efficacy of superhydrophilic and superhydrophobic copper surfaces on high-touch facilities such as elevator buttons with smooth copper and stainless steel surfaces in preventing the transfer of infections through hospital surfaces. It was found that the wettability of frequently touched surfaces like elevator buttons matters for combating bacterial contamination. The total aerobic microbial counts, encompassing both pathogenic and nonpathogenic microbial contamination, were similar across smooth, superhydrophobic, and superhydrophilic copper coatings. At the same time, surfaces with extreme wettability exhibited a lower incidence of Staphylococcus aureus growth, no growth of Acinetobacter spp., and reduced maximum contamination levels for both pathogens and nonpathogenic bacteria. Superhydrophilic buttons treated with the quaternary ammonium compound miramistin showed a reduction in microbial growth during the initial 20 days. The study emphasizes the importance of surface wettability and texture in mitigating microbial contamination.

Figure 1

Variation over exposure time in a cumulative number of contaminated swabs taken from elevator buttons with various wettabilities determined by binary count (a) and logarithmic count (b). “Control” in legend stands for stainless steel buttons; “Cu” for untreated copper buttons; “Phil” for laser-treated superhydrophilic copper buttons; “Phob” for laser-treated superhydrophobic copper buttons. TAMC denotes the total aerobic microbial count.

Figure 2

Variation over exposure time in the cumulative logarithm of the total aerobic microbial count (TAMC) from contaminated swabs collected from superhydrophilic copper elevator buttons. “Phil” in legend stands for laser-treated superhydrophilic copper buttons, while “Miramistin” for those that were replenished with miramistin after each swab was taken.

Figure 3

Fraction of contaminated swabs collected from elevator buttons.

Figure 4

Species and genus of microorganisms most frequently isolated from tested elevator buttons: (a) number of swabs where a particular strain was detected; (b) maximal contamination levels detected for the strain.

Figure 5

Water contact angles on test surfaces before and after evaluating their antibacterial effects under clinical conditions: (1) stainless steel; (2) smooth copper; (3) superhydrophilic copper; (4) superhydrophobic copper; and (5) superhydrophilic copper impregnated with the miramistin.

Figure 6

SEM images of the surfaces of superhydrophilic copper elevator buttons before (a, c) and after (b, d) 6 months of clinical tests.

Figure 7

3D maps of the elevator button surfaces with various wettabilities before and after the clinical tests.