Potential for Preventing Spread of Fungi in Air-conditioning Systems Constructed Using Copper Instead of Aluminium

Weaver L, Michels HT, Keevil CW. Lett Appl Microbiol. 2010 Jan;50(1):18-23.

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Aims: As copper has been previously suggested as an antimicrobial surface, we tested the effectiveness of copper as an antifungal surface which could be used in air-conditioning systems as an alternative to aluminium.

Methods and Results: Coupons of copper (C11000) and aluminium were inoculated with fungal isolates (Aspergillus spp., Fusarium spp., Penicillium chrysogenum and Candida albicans) for various time periods. Culture on potato dextrose agar and an in situ viability assay using the fluorochrome FUN-1 were used to determine whether spores had survived. The results showed increased die off of fungal isolates tested compared to aluminium. In addition, copper also prevented the germination of spores present, thereby reducing the risk of the release of spores.

Conclusions: Copper offered an antifungal surface and prevented subsequent germination of spores present. FUN-1 demonstrated that fungal spores entered into a viable but not culturable (VBNC) state on copper indicating the importance of using such methods when assessing the effect of an antifungal as culture alone may give false results.

Significance and impact of study: Copper offers a valuable alternative to aluminium which could be used in air-conditioning systems in buildings, particularly in hospital environments where patients are more susceptible to fungal infections.