Three novel highly charged copper-based biocides: safety and efficacy against healthcare-associated organisms.
OBJECTIVE
We investigated three novel highly charged copper-based inorganic biocidal formulations for their activity against organisms highly relevant to healthcare-associated infection.


METHODS
The three copper-based formulations were tested: (i) against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), Legionella pneumophila, Acinetobacter calcoaceticus/baumannii (ACCB), glycopeptide-resistant Enterococcus and spores of Clostridium difficile in time-kill assays; (ii) for their ability to decontaminate ultramicrofibre (UMF) cloths; and (iii) for their cytotoxicity to human skin and intestinal epithelial cells.


RESULTS
All three copper-based formulations were potently biocidal down to concentrations of 1 ppm for both stationary- and log-phase organisms, and they were all active against C. difficile spores. At 150 ppm, they achieved a complete (>6 log10) kill of MRSA and ACCB mostly within 1 h. This biocidal activity was not achieved by copper sulphate or the inorganic binders used in the formulations. All three copper-based formulations completely decontaminated UMF cloths containing MRSA, ACCB or C. difficile spores, suggesting that any of these copper-based formulations would be highly beneficial in the healthcare environment. All three copper-based formulations and copper sulphate were not cytotoxic to human epithelial cells up to concentrations of 100-200 ppm.


CONCLUSIONS
All three of the novel copper-based biocidal formulations, but not their components (copper sulphate and inorganic binders), have potent activity against organisms highly relevant to healthcare-associated infections.
Gant
Vanya A
VA
Department of Microbiology, University College Hospitals NHS Foundation Trust, London W1T 4JF, UK. vanya.gant@uclh.nhs.uk
Wren
Michael W D
MW
Rollins
Michael S M
MS
Jeanes
Annette
A
Hickok
Stephen S
SS
Hall
Tony J
TJ
D001419:Bacteria / Q000187:drug effects*; D001424:Bacterial Infections / Q000382:microbiology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002626:Chemistry, Pharmaceutical; D015169:Colony Count, Microbial; D003300:Copper / Q000009:adverse effects / Q000737:chemistry* / Q000633:toxicity*; D019327:Copper Sulfate / Q000494:pharmacology; D004202:Disinfectants / Q000009:adverse effects / Q000737:chemistry* / Q000494:pharmacology / Q000633:toxicity*; D024881:Drug Resistance, Bacterial; D004847:Epithelial Cells / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D016106:Methicillin Resistance; D012867:Skin / Q000166:cytology / Q000187:drug effects; D013171:Spores, Bacterial / Q000187:drug effects
D004202:Disinfectants; D003300:Copper; D019327:Copper Sulfate