Effect of Monochloramine Treatment on Colonization of a Hospital Water Distribution System by Legionella spp.: A 1 Year Experience Study
journal contributionposted on 07.04.2015, 00:00 by Benedetta Mancini, Maria Scurti, Ada Dormi, Antonella Grottola, Andrea Zanotti, Sandra Cristino
Contamination of hot water distribution systems by Legionella represents a great challenge due to difficulties associated with inactivating microorganisms, preserving the water characteristics. The aim of this study was to examine over the course of 1 year in 11 fixed sites, the impact of monochloramine disinfection on Legionella, heterotrophic bacteria (36 °C), Pseudomonas aeruginosa contamination, and chemical parameters of a plumbing system in an Italian hospital. Three days after installation (T0), in the presence of monochloramine concentration between 1.5 and 2 mg/L, 10/11 sites (91%) were contaminated by L. pneumophila serogroups 3 and 10. After these results, the disinfectant dosage was increased to between 6 and 10 mg/L, reducing the level of Legionella by three logarithmic unit by 2 months postinstallation (T2) until 6 months later (T3). One year later (T4), there was a significant reduction (p = 0.0002) at 8/11 (73%) sites. Our data showed also a significant reduction of heterotrophic bacteria (36 °C) in 6/11 (55%) sites at T4 (p = 0.0004), by contrast the contamination of P. aeruginosa found at T0 in two sites persisted up until T4. The results of the present study show that monochloramine is a promising disinfectant that can prevent Legionella contamination of hospital water supplies.
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2 months postinstallationpneumophila serogroups 3logarithmic unitaeruginosaLegionella contaminationmonochloramine disinfectionbacteriaT 4T 0disinfectant dosage1 yearwater characteristicsplumbing systemchemical parameters6 monthsItalian hospitalmgHospital Water Distribution Systemsitewater distribution systemshospital water suppliesmonochloramine concentrationstudy showT 4.Monochloramine Treatmentheterotrophicinactivating microorganisms1 Year Experience StudyContamination