Laboratory-based study of novel antimicrobial cold spray coatings to combat surface microbial contamination.

Lucas, M D I; Botef, I; Reid, R G; van Vuuren, S F

OBJECTIVE To investigate the touch-contact antimicrobial efficacy of novel cold spray surface coatings composed of copper and silver metals, regard to their rate of microbial elimination. DESIGN Antimicrobial time-kill assay. SETTING Laboratory-based study. METHODS An adapted time-kill assay was conducted to characterize the antimicrobial efficacy of the developed coatings. A simulated touch-contact pathogenic exposure to Gram-positive Staphylococcus aureus (ATCC 25923), Gram-negative Pseudomonas aeruginosa (ATCC 27853), and the yeast Candida albicans (ATCC 10231), as well as corresponding resistant strains of gentamicin-methicillin-resistant S. aureus (ATCC 33592), azlocillin-carbenicillin-resistant P. aeruginosa (DSM 46316), and a fluconazole-resistant C. albicans strain was undertaken. Linear regression modeling was used to deduce microbial reduction rates. RESULTS A >7 log reduction in microbial colony forming units was achieved within minutes on surfaces with cold spray coatings compared to a single log bacterial reduction on copper metal sheets within a 3 hour contact period. Copper-coated 3-dimensional (3D) printed acrylonitrile butadiene styrene (ABS) achieved complete microbial elimination against all tested pathogens within a 15 minute exposure period. Similarly, a copper-on-copper coating achieved microbial elimination within 10 minutes and within 5 minutes with the addition of silver powder as a 5 wt% coating constituent. CONCLUSIONS In response to the global need for alternative solutions for infection control and prevention, these effective antimicrobial surface coatings were proposed. A longitudinal study is the next step toward technology integration.