Antimicrobial efficacy of a thermal spray copper alloy coating in a hospital setting

McGeer1, M. Gardam1 R. Peters1, P. Reason1, A. Marques1,
T. Portman2, T. Cassady3, M. Ringuette4, J. Mostaghimi4, L. Pershin4, A.
ICAAC 2013 Presentation Abstract, Session 165

Background

Copper is being increasingly considered for surfaces in healthcare settings due to its antimicrobial activity; however, few published studies of clinical efficacy are available and copper surfaces are expensive. Thermal spray coatings may be a practical and cost effective alternative to sheet metal copper alloy. The aim of this study was to evaluate the antimicrobial efficacy of a thermal spray copper coating in a clinical environment.

Methods

Waiting room chairs were built with either standard plastic arms or arms with a thermal spray copper alloy coating. Thirty-eight each of copper coated and control chairs were installed in a waiting area for admitting and phlebotomy in a tertiary care hospital. On 4 occasions, 32 chair arm surfaces (16 copper:16 plastic) were sampled using a 2.5×15.8cm plastic template and a e-swab moistened in transport media. Swabs were transferred to 1ml of sterile neutralizing broth, and cultured semiquantitatively on sheep blood and selective agars, with colonies counted after incubating aerobically for 18-24 hours at 37oC. Microbiology staff were blinded as to the chair surface. Presumptive pathogens were identified using standard methodology and MALDI-TOF. The primary outcome was the difference in the CFU/cm2 from copper and non-copper surfaces.

Results

Colony counts from swabs of copper and control chair arms are shown in the Table. Overall, the median colony count was 68% lower in samples from copper coated v. plastic arms (P<.0001). No MRSA, VRE or Enterobacteriaceae were identified. Potential pathogens were identified from 4/64 copper and 7/64 control chair arm cultures (P=.52), and included viridans group streptococci (N=8), M. luteus (N=2), and S. aureus, Acinetobacter and A. viridans (N=1 each).

Conclusions

Thermal spray copper surfaces have persistent antimicrobial activity and may be of value in healthcare environments.