The ability of Legionella pneumophila to colonise domestic water systems is a primary cause of outbreaks of Legionnaire's disease in humans. World Health Organization guidelines recommend that drinking water is chlorinated to between 0.2 and 1 mg/L [Chlorine in drinking-water. Guidelines for drinking-water quality, 2nd edn. Geneva: World Health Organization; 1996], but L. pneumophila is repeatedly isolated from chlorinated water systems, indicating that this treatment is not effective at preventing colonisation. Current UK guidelines recommend a one-off treatment of 20–50 mg/L of free chlorine to remove the bacteria. In this study we report on the persistence of L. pneumophila serogroup 1 in a domestic shower system despite repeated cycles of chlorination at 50 mg/L for 1 h exposure time, over the course of two and a half years. Persisting isolates were subjected to in-vitro phenotypic analyses and polymerase chain reaction analysis for the toxin-encoding mip gene. Random amplified polymorphic DNA typing was also performed to determine whether the isolates recovered on different occasions were the same strain. We found that seven isolates of L. pneumophila recovered over a two-and-a-half year period are the same genetically defined strain, indicating that the bacteria can persist despite repeated cycles of chlorination after each successive isolation.
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- Advances in the epidemiology and control of Legionella.Epidemiol Rev. 1991; 13: 329-335
- Preventing Legionellosis.International Water Association Publishing, London2005 (p. 11–30)
- Legionellosis.Infect Dis Clin North Am. 1991; 5: 561-584
- Legionnaire's disease associated with potting soil – California, Oregon, and Washington, May–June 2000. Canada Communicable Disease Report – Releve Des Maladies Transmissibles Au Canada. 2000; 26: 189-192
- A comparison of Legionella pneumophila occurrence in hot water tanks and instantaneous devices in domestic, nosocomial and community environments.Curr Microbiol. 2000; 41: 374-376
- Occurrence of Legionella in hot water systems of single-family residences in suburbs of two German cities with special reference to solar and district heating.Int J Hyg Environ Health. 2008; 211: 179-185
- Presumptive identification of Legionella species, BSOP ID 18.Health Protection Agency, London2003
- Water quality detection and enumeration of Legionella (ISO 11731-2:2004; BS 6068-4.18:2004).British Standards Institute, London2004
- A multiplex PCR for detection of Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, and Bordetella pertussis in clinical specimens.Mol Cell Probes. 2005; 19: 314-322
- Random amplified polymorphic DNA typing of Pseudomonas aeruginosa isolates recovered from patients with cystic fibrosis.J Clin Microbiol. 1996; 34: 1129-1135
- Identification of DNA markers for a transmissible Pseudomonas aeruginosa cystic fibrosis strain.Am J Respir Cell Mol Biol. 2005; 33: 56-64
Published online: May 17, 2010
Accepted: June 13, 2008
Received: June 2, 2008
© 2008 The Hospital Infection Society. Published by Elsevier Inc. All rights reserved.