Susceptibility of 169 USA300 methicillin-resistant Staphylococcus aureus isolates to two copper-based biocides, CuAL42 and CuWB50.

OBJECTIVES: To test the activity of two copper-based biocides, CuAL42 and CuWB50, and benzalkonium chloride against 169 isolates of methicillin-resistant Staphylococcus aureus (MRSA) pulsotype USA300, a virulent, multiply resistant, widespread clone in the USA. METHODS: Tests including MIC, MBC and time-kill studies were performed multiple times. RESULTS: The MIC range, MIC(50) and MIC(90) (0.59-18.75, 4.69 and 4.69 ppm, respectively) and the MBC range, MBC(50) and MBC(90) (1.17-18.75, 4.69 and 9.38 ppm, respectively) for CuAL42 were identical with those obtained with CuWB50, except that the MBC range for CuWB50 was wider (0.59-37.5 ppm). In time-kill studies, a 6 log(10) reduction of cfu was achieved within 1 h (150 ppm) and 0.5 h (300 ppm) for CuAL42, and 1.5 h (150 ppm) and 0.75 h (300 ppm) for CuWB50. CONCLUSIONS: Both copper-based biocides can effectively kill USA300 MRSA and may facilitate the eradication of the organism from healthcare settings.

Decontamination of laundry at low temperature with CuWB50, a novel copper-based biocidal compound.

BACKGROUND: Traditional laundry decontamination relies on thermal disinfection that degrades textiles. We investigated the ability of a novel copper-based biocidal compound, CuWB50, to assist in the decontamination of swatches purposely contaminated with Staphylococcus aureus and Acinetobacter during "real-life" low-temperature machine washing with and without 2 commercial detergents. METHODS: Contaminated and noncontaminated swatches were attached to ballast sheets and washed in cold water for 15 minutes in an industrial Electrolux machine. We assessed colony-forming units (cfu) on the swatches and in the postwash water. RESULTS: Low-temperature machine washing produced only partial reductions in viable methicillin-resistant Staphylococcus aureus and Acinetobacter calcoaceticus baumannii counts on swatches and resulted in cross contamination of other swatches in the same wash. Washing with CuWB50 alone at high concentration (100 mg/L), however, resulted in superior decontamination compared with water alone, whereas washing with a combination of detergent and CuWB50 at low concentration (5 mg/L) yielded synergistic and complete decontamination of swatches and postwash water. CONCLUSION: Our results show highly effective laundry decontamination using CuWB50 with detergent at low temperature and are timely both in terms of rising energy costs and textile degradation issues.

A comparison of the antibacterial efficacy and cytotoxicity to cultured human skin cells of 7 commercial hand rubs and Xgel, a new copper-based biocidal hand rub.

BACKGROUND: Hand cleanliness is important in hospital infection control, but skin irritation from frequent alcohol-based hand rub use reduces compliance. We have compared a new copper biocide/Aloe vera-based biocidal hand rub (Xgel) with 7 commercially available hand rubs. METHODS: Hand rubs were cultured with human skin cells for 24 hours after which cytotoxicity was assessed using the sulforhodamine B assay. The EN 12054 bacterial suspension test protocol was used to assess biocidal activity of 2 of the least cytotoxic hand rubs (Xgel and Purell). RESULTS: Hand rubs had 50% cytotoxic concentrations ranging from >10% to <0.1% vol/vol. In the EN12054 assay, Xgel reduced colony forming units (CFU) by >10(8) with methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter in 1 minute, whereas Purell only reduced CFU by 10(4) and 10(5), respectively. Purell was ineffective against C difficile spores, whereas Xgel produced a 3 x 10(3) reduction in CFU. CONCLUSION: The hand rubs had a wide range of cytotoxicity values for human skin cells, with Xgel being the least cytotoxic to human skin cells. In the EN 12054 bacterial suspension test, Xgel was more effective than Purell against all organisms tested. It should be noted that these in vitro results may not translate into clinical differences.

Effect of oral gavage treatment with ZnAL42 and other metallo-ion formulations on influenza A H5N1 and H1N1 virus infections in mice.

Avian influenza H5N1 infections can cause severe, lethal human infections. Whether influenza A virus treatments effectively ameliorate avian influenza H5N1 human infections is uncertain. The research objective was to evaluate the efficacy of novel zinc and other metallo-ion formulations in two influenza A mouse models. Mice infected with influenza A/Duck/MN/1525/81 (H5N1) virus were treated orally 48 h before virus exposure and then twice daily for 13 days with ZnAL42. The optimal dosing regimen for ZnAL42 was achieved at 17.28 mg/kg 48 h prior to virus exposure, twice daily for 7 days. The survival rate was 80% compared with 10% in the untreated control group and a 100% survival rate with ribavirin (75 mg/kg/day, twice a day for 5 days, beginning 4 h before virus exposure). ZnAL42 treatment significantly lessened the decline in arterial oxygen saturation (SaO2; P < 0.001). This regimen was also well tolerated by the mice. Manganese and selenium formulations were not inhibitory to virus replication when given therapeutically. Mice were also infected with influenza A/NWS/33 (H1N1) virus and were treated 48 h before virus exposure with three dosages of ZnAL42 (8.64, 1.46 or 0.24 mg/kg/day). Treatment was by oral gavage twice daily for 13 days. The highest dose of ZnAL42 was significantly inhibitory to the virus infection as seen by prevention of deaths and lessening of decline in SaO2. The data suggest that the prophylactic use of ZnAL42 is effective against avian influenza H5N1 or H1N1 virus infection in mice and should be further explored as an option for treating human influenza virus infections.

Three novel highly charged copper-based biocides: safety and efficacy against healthcare-associated organisms.

OBJECTIVES: 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.