Effectiveness of a neutral electrolysed oxidising water (NEOW) device in reducing Legionella pneumophila in a water distribution system: A comparison between culture, qPCR and PMA-qPCR detection methods. (November 2018)

• Record Type: Journal Article
• Authors: Bonetta, Sara; Pignata, Cristina; Bonetta, Silvia; Meucci, Lorenza; Giacosa, Donatella; Marino, Elena; Gorrasi, Ilaria; Gilli, Giorgio; Carraro, Elisabetta
• Is Part Of: Chemosphere. Volume 210(2018)
• Page Start: 550
• Page End: 556
• Publication Date: 2018-11
• Subjects: Legionella pneumophila -- Hot water -- Neutral electrolysed oxidising water -- Propidium monoazide -- qPCR; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.07.053
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Disinfection of hot water systems is critical for reducing Legionnaires' disease in high-risk buildings. The use of neutral electrolysed oxidising water (NEOW) is a promising method for the control of microorganisms in hot water systems. However, full-scale evaluations of the efficacy of NEOW devices to control Legionella pneumophila are currently lacking. The aim of this study was to assess the effectiveness of a NEOW device in reducing L. pneumophila in a hotel water network. Water samples (n = 67) were collected from different sites of a hotel distribution system before and after the installation of the NEOW device at the 1st, 4th, 8th and 12th week. Detection of L. pneumophila was performed comparing culture, qPCR and PMA-qPCR methods. Total bacterial counts (22 °C and 37 °C), Pseudomonas spp. and physico-chemical parameters were also monitored. The NEOW treatment resulted in a reduction of the amount of L. pneumophila positive samples (−32%) and of the number of heavily contaminated points (>10 4 CFU/L and >10 3 CFU/L) (−100% and −96%, respectively). Treatment maintained L. pneumophila at low levels (<10 2 CFU/L), which do not require specific intervention measures. The effectiveness of the disinfection system was also confirmed by PMA-qPCR (p < 0.001). The use of PMA resulted in a signal decrease in almost all samples upon the disinfection treatment. The NEOW disinfection device appears to be a promising approach to reduce the colonisation of hot water systems by L. pneumophila ; however, further investigations are needed to ascertain its efficiency over longer time periods. Graphical abstract: Image 1 Highlights: The NEOW disinfection device reduced L. pneumophila contamination in a hot water system. The treatment maintained L. pneumophila at low levels (<10 2 CFU/L). A significant correlation was observed between L. pneumophila and bacterial counts. L . pneumophila measurements via PMA-qPCR were also affected by the NEOW treatment. PMA-qPCR allowed to reveal dead/compromised cells as a result of the NEOW treatment.