Influence of copper surfaces on biofilm formation by Legionella pneumophila in potable water
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Legionella pneumophila is a waterborne pathogen that can cause Legionnaires’ disease, a fatal pneumonia, or Pontiac fever, a mild form of disease. Copper is an antimicrobial material used for thousands of years. Its incorporation in several surface materials to control the transmission of pathogens has been gaining importance in the past decade. In this work, the ability of copper to control the survival of L. pneumophila in biofilms was studied. For that, the incorporation of L. pneumophila in polymicrobial drinking water biofilms formed on copper, PVC and PEX, and L. pneumophila mono-species biofilms formed on copper and uPVC were studied by comparing cultivable and total numbers (quantified by peptide nucleic acid (PNA) hybridisation). L. pneumophila was never recovered by culture from heterotrophic biofilms; however, PNA-positive numbers were slightly higher in biofilms formed on copper (5.9 × 105 cells cm−2) than on PVC (2.8 × 105 cells cm−2) and PEX (1.7 × 105 cells cm−2). L. pneumophila mono-species biofilms grown on copper gave 6.9 × 105 cells cm−2 for PNA-positive cells and 4.8 × 105 CFU cm−2 for cultivable numbers, showing that copper is not directly effective in killing L. pneumophila. Therefore previous published studies showing inactivation of L. pneumophila by copper surfaces in potable water polymicrobial species biofilms must be carefully interpreted.
KeywordsLegionella pneumophila Drinking water biofilms PNA hybridisation Copper
This research was supported by the Copper Development Association, New York, NY, and the International Copper Association, New York, NY. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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