Effects of temperature and humidity on the efficacy of methicillin-resistant Staphylococcus aureus challenged antimicrobial materials containing silver and copper.

Copper Development Association Inc., New York, NY 10016, USA.
Letters in Applied Microbiology (Impact Factor: 1.63). 04/2009; 49(2):191-5. DOI: 10.1111/j.1472-765X.2009.02637.x
Source: PubMed

ABSTRACT To compare silver and copper, metals with known antimicrobial properties, by evaluating the effects of temperature and humidity on efficacy by challenging with methicillin resistant Staphylococcus aureus (MRSA).
Using standard methodology described in a globally used Japanese Industrial Standard, JIS Z 2801, a silver ion-containing material exhibited >5 log reduction in MRSA viability after 24 h at >90% relative humidity (RH) at 20 degrees C and 35 degrees C but only a <0.3 log at approximately 22% RH and 20 degrees C and no reduction at approximately 22% RH and 35 degrees C. Copper alloys demonstrated >5 log reductions under all test conditions.
While the high humidity (>90% RH) and high temperature (35 degrees C) utilized in JIS Z 2801 produce measurable efficacy in a silver ion-containing material, it showed no significant response at lower temperature and humidity levels typical of indoor environments.
The high efficacy levels displayed by the copper alloys, at temperature and humidity levels typical of indoor environments, compared to the low efficacy of the silver ion-containing material under the same conditions, favours the use of copper alloys as antimicrobial materials in indoor environments such as hospitals.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The bacterial infections associated with metallic surfaces in the clinical environments obviously lead to vulnerable diseases. A protective layer on these surfaces is imperative, so as to reduce the risk of infections due to microbes. From this perspective, the Cu based single layer and multilayer coatings were grown on 316L stainless steel (SS) and titanium substrates by the DC magnetron sputtering technique. These coatings were characterized by the X-ray diffraction (XRD), scanning electron microscope (SEM), field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM) and energy dispersive X-ray analysis (EDX). The evaluation of nanomechanical properties, surface wettability and antimicrobial efficacy of the coatings was also carried out in detail. The antimicrobial properties of the coatings were studied against Gram-positive bacteria (S. aureus) by two methods: disc diffusion method and fluorescence staining. The single layer Cu coating at 200 ?C and [Cu/Ti]25 multilayer coatings on both substrates exhibited enhanced antimicrobial activity. However, the nanomechanical properties were found to be four times higher for the multilayers than for the single layer coatings.
    Materials Express 12/2014; 4(6). · 1.72 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Copper and silver are used as antimicrobial agents in the healthcare sector in an effort to curb infections caused by bacteria resistant to multiple antibiotics. While the bactericidal potential of copper and silver alone are well documented, not much is known about the antimicrobial properties of copper–silver alloys. This study focuses on the antibacterial activity and material aspects of a copper–silver model alloy with 10 wt% Ag. The alloy was generated as a coating with controlled intermixing of copper and silver on stainless steel by a laser cladding process. The microstructure of the clad was found to be two-phased and in thermal equilibrium with minor Cu2O inclusions. Ion release and killing of Escherichia coli under wet conditions were assessed with the alloy, pure silver, pure copper and stainless steel. It was found that the copper–silver alloy, compared to the pure elements, exhibited enhanced killing of E. coli, which correlated with an up to 28-fold increased release of copper ions. The results show that laser cladding with copper and silver allows the generation of surfaces with enhanced antimicrobial properties. The process is particularly attractive since it can be applied to existing surfaces.
    Applied Surface Science 11/2014; 320:195–199. · 2.54 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: ABSTRACT Aims: The ethanolic extracts of stem bark and fruit pulp as well as saponins from Dialium guineense were assayed for antibacterial activity against Gram positive and 2201 negative strains and clinical strains of methicilin resistant Staphylococcus aureus (MRSA) isolated from different locations on human body aged 20-30 years within the University of Nigeria community. Methodology: Agar diffusion technique was adopted. Results: The results showed that MRSA is predominant in apparently healthy population of the University community with 100% in males and 92.3% females showing positive case in nasal swab, 87.5% and 96.6 % positive from ear swabs of male and female volunteers respectively; and 77.7% positive from the high vaginal swabs of females. MRSA and other clinical isolates showed higher susceptibility to saponins compared to crude extracts; however, Bacillus cereus (NRRL 14724 and 14725) were not susceptible to the saponins from D. guineense. The MICs of the saponins were 31.25 mg/mL (B. subtilis ATCC 6051, P. aeruginosa, S. typhi, S. knitambo, P. mirabilis and S. aureus), 62.50 mg/mL (E. coli) and 125 mg/mL (P. aeruginosa ATCC 10145). Comparable MICs of higher values were obtained with the crude ethanolic extracts of stem bark and fruit pulp against MRSA and clinical isolates. Conclusion: The present findings revealed wide distribution of MRSA in an apparently healthy population in Nigeria and the susceptibility patterns showed the presence of a broad spectrum antibacterial agent in D. guineense.
    british journal pharmaceutical research. 08/2014; 4(4):2200-2209.

Full-text (2 Sources)

Available from
May 31, 2014