Article

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: 1.75). 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.

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    • "Cu is widely used for its antimicrobial properties (Borkow and Gabbay, 2009; Grass et al., 2011). Cu and Cu alloy surfaces have been shown to kill a variety of pathogens including Salmonella enterica and Campylobacter jejeuni (Faundez et al., 2004), Listeria monocytogenes (Wilks et al., 2006), methicillin resistant Staphylococcus aureus (MRSA; Noyce et al., 2006a; Gould et al., 2009; Michels et al., 2009; Weaver et al., 2010), Escherichia coli O157 (Wilks et al., 2005; Noyce et al., 2006b), Mycobacterium tuberculosis (Mehtar et al., 2008), Clostridium difficile "
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    • "In our hands, silver surfaces did not kill bacteria (Nies and Nies, unpublished observations). In line with this observation, copper alloys indeed were much more efficient as antimicrobial materials than silver-containing materials at temperature and humidity levels typical for indoor environments such as hospitals (Michels et al. 2009). "
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