Effects of Temperature and Humidity on the Efficacy of Methicillin-Resistant Staphylococcus Aureus Challenged Antimicrobial Materials Containing Silver and Copper

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

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Colony Count, Microbial
  • Copper / pharmacology*
  • Humidity*
  • Methicillin-Resistant Staphylococcus aureus / growth & development*
  • Microbial Viability / drug effects
  • Silver / pharmacology*
  • Temperature*

Substances

  • Anti-Bacterial Agents
  • Silver
  • Copper