Effect of monochloramine treatment on colonization of a hospital water distribution system by Legionella spp.: a 1 year experience study.
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.
Benedetta
B
Mancini
Maria
M
Scurti
Ada
A
Dormi
§Regional Reference Laboratory for Clinical Diagnosis of Legionellosis, Unit of Microbiology and Virology, Modena University Hospital, via del Pozzo 71, 41124, Modena, Italy.
Antonella
A
Grottola
⊥ITACA srl ITACA s.r.l., via Remigia, 19, 40068, San Lazzaro di Savena (BO), Italy.
Andrea
A
Zanotti
Sandra
S
Cristino
D001419:Bacteria / Q000187:drug effects; D002700:Chloramines / Q000494:pharmacology*; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection; D060766:Drinking Water / Q000382:microbiology*; D006761:Hospitals; D007558:Italy; D007875:Legionella / Q000187:drug effects*; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D014881:Water Supply
D002700:Chloramines; D004202:Disinfectants; D060766:Drinking Water; C030816:chloramine