Effectiveness of different methods to control legionella in the water supply: ten-year experience in an Italian university hospital

• Published in: The Journal of hospital infection Vol. 77; no. 1; pp. 47 - 51
• Main Authors: Marchesi, I, Marchegiano, P, Bargellini, A, Cencetti, S, Frezza, G, Miselli, M, Borella, P
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.01.2011; Elsevier
• Subjects: Bacterial diseases; Bacterial diseases of the respiratory system; Bacterial Load; Biological and medical sciences; Costs; Cross Infection - prevention & control; Disinfectants - pharmacology; Disinfection; Disinfection - methods; Effectiveness; Epidemiology. Vaccinations; Filtration - methods; General aspects; Hospital-acquired Legionnaires’ disease; Hospitals, University; Hot Temperature; Hot water distribution system; Human bacterial diseases; Human infectious diseases. Experimental studies and models; Humans; Infection Control - methods; Infectious Disease; Infectious diseases; Italy; Legionella; Legionella - isolation & purification; Medical sciences; Water Microbiology; Water Supply; Italy; Hospital-acquired Legionnaires’ disease; Disinfection; Costs; Legionella; Effectiveness; Hot water distribution system; Nosocomial infection; Pneumonia; Water supply; Check; Legionellosis; Water distribution; Legionnaires disease; Prevention; Bacteria; Hospital; Public health; Hospital-acquired Legionnaires' disease; Lung disease; Legionellaceae; Respiratory disease; Method; Tap water; Hot water; Infection; Health economy; Bacteriosis; Distribution system
• ISSN: 0195-6701; 1532-2939
• DOI: 10.1016/j.jhin.2010.09.012

Summary We report our ten-year experience of hyperchlorination, thermal shock, chlorine dioxide, monochloramine, boilers and point-of-use filters for controlling legionella contamination in a hospital hot water distribution system. Shock disinfections were associated with a return to pre-treatment contamination levels within one or two months. We found that chlorine dioxide successfully maintained levels at <100 cfu/L, whilst preliminary experiments gave satisfactory results with monochloramine. No contamination was observed applying point-of-use filters and electric boilers at temperatures of >58 °C and no cases of nosocomial legionellosis were detected in the ten-year observation period. Our performance ranking in reducing legionella contamination was filter, boiler, chlorine dioxide, hyperchlorination and thermal shock. Chlorine dioxide was the least expensive procedure followed by thermal shock, hyperchlorination, boiler and filter. We suggest adopting chlorine dioxide and electric boilers in parallel.