title: Monochloramine and chlorine dioxide for controlling Legionella pneumophila contamination: biocide levels and disinfection by-product formation in hospital water networks.
abstract: Legionella colonization in hospital hot water distribution networks was evaluated following 36 months of continuous treatment with monochloramine and compared with chlorine dioxide. Nitrite, nitrate, chlorite, chlorate, bromide, trihalomethanes and haloacetic acids as well as the biocide concentration at sampled points were measured. Only 8/84 samples treated with monochloramine were found contaminated and after the first 8 months of treatment no Legionella was isolated. Chlorine dioxide was associated with a strong reduction in Legionella contamination compared to pre-treatment, but differences according to the device were observed. Monochloramine between 2 and 3 mg l(-1) and chlorine dioxide between 0.50 and 0.70 mg l(-1) were needed to control Legionella colonization. Comparing no- and post-flush samples, a higher frequency of no-flush positive samples was noted using chlorine dioxide, suggesting an increased risk for patients when they open the tap. No increase in chlorite levels and no water nitrification occurred by using monochloramine. Chlorite at levels exceeding the limit requested for drinking water was measured when chlorine dioxide was applied. In conclusion, we highlight that continuous injection of monochloramine should be considered as an effective alternative to chlorine dioxide in controlling legionellae contamination inside hospital water distribution systems.
authors: Department of Diagnostic, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Via Campi 287, I-41125 Modena, Italy E-mail: isabella.marchesi@unimore.it.
authors: Isabella
authors: I
authors: Marchesi
authors: Department of Diagnostic, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Via Campi 287, I-41125 Modena, Italy E-mail: isabella.marchesi@unimore.it.
authors: Greta
authors: G
authors: Ferranti
authors: Department of Diagnostic, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Via Campi 287, I-41125 Modena, Italy E-mail: isabella.marchesi@unimore.it.
authors: Annalisa
authors: A
authors: Bargellini
authors: University Hospital Policlinico of Modena, Via del Pozzo 71, I-41124 Modena, Italy.
authors: Patrizia
authors: P
authors: Marchegiano
authors: Department of Diagnostic, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Via Campi 287, I-41125 Modena, Italy E-mail: isabella.marchesi@unimore.it.
authors: Guerrino
authors: G
authors: Predieri
authors: Special Pathogens Laboratory, 1401 Forbes Ave. Suite 209, Pittsburgh, PA 15219, USA and Swanson School of Engineering, University of Pittsburgh, 3700 O'Hara Street, Pittsburgh, PA 15261, USA.
authors: Janet E
authors: JE
authors: Stout
authors: Department of Diagnostic, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Via Campi 287, I-41125 Modena, Italy E-mail: isabella.marchesi@unimore.it.
authors: Paola
authors: P
authors: Borella
mesh_terms: D002700:Chloramines / Q000494:pharmacology*; D017606:Chlorine Compounds / Q000494:pharmacology*; D004202:Disinfectants / Q000494:pharmacology; D004203:Disinfection / Q000379:methods*; D006761:Hospitals; D016952:Legionella pneumophila / Q000187:drug effects*; D010087:Oxides / Q000494:pharmacology*; D013997:Time Factors; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods
chemical_list: D002700:Chloramines; D017606:Chlorine Compounds; D004202:Disinfectants; D010087:Oxides; C025109:chlorine dioxide; C030816:chloramine