Efficacy of copper-silver ionization for controlling fungal colonization in water distribution systems.

The purpose of this study was to identify the prevalence of fungal colonization in water systems and to evaluate the effect of decreasing fungal colonization by a copper-silver ionization system. Environmental samples were collected for fungal culture prospectively during a 1-year period (2011-2012) at the study hospital. A total of 392 water samples were examined from five buildings on March 1, 2011 and February 29, 2012. Fungi were isolated in 13 (3.4%) of 392 water samples from five buildings. The prevalence of fungal colonization in buildings was decreased from 4.76% (9/189) to 1.97% (4/203), a reduction of more than 40%, in pre-ionization and post-ionization treatment (p < 0.001). Thirteen (3.4%) of 392 water samples yielded fungi including Fusarium species (n = 7), Penicillium species (n = 2), Scedosporium species (n = 2), Aspergillus species (n = 1), and one unidentifiable mold. The number of isolated Fusarium species in ionized water samples (0.5% (1/203)) was statistically lower than those in nonionized (3.2% (6/189)) (p = 0.003). Our finding may determine if this ionization method can be applied for control of waterborne fungi colonization in hospital water systems.