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. 2009 Aug;49(2):191-5.
doi: 10.1111/j.1472-765X.2009.02637.x. Epub 2009 Apr 25.

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

H T Michels  1 , J O Noyce, C W Keevil
Affiliations
Free PMC article

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

H T Michels et al. Lett Appl Microbiol. 2009 Aug.
Free PMC article

Abstract

Aims: 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).

Methods and results: 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.

Conclusions: 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.

Significance and impact of the study: 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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Figures

Figure 1
Figure 1
MRSA viability at ∼22°C and ∼50% RH on C11000 copper (•), two silver-ion containing materials, Ag-A (Δ), and Ag-B (◊) and S30400 stainless steel (□).
See this image and copyright information in PMC

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