Long-Term Survival of Legionella pneumophila in the Viable But Nonculturable State After Monochloramine Treatment

• Published in: Current microbiology Vol. 57; no. 5; pp. 497 - 502
• Main Authors: Alleron, Laëtitia, Merlet, Nicole, Lacombe, Christian, Frère, Jacques
• Format: Journal Article
• Language: English
• Published: New York Springer-Verlag 01-11-2008; Springer Nature B.V
• Subjects: Acanthamoeba castellanii; Acanthamoeba castellanii - microbiology; Amoeba; Animals; Aquatic environment; Biofilms; Biomedical and Life Sciences; Biotechnology; Charcoal; Chloramines - pharmacology; Disinfectants - pharmacology; Legionella pneumophila; Legionella pneumophila - drug effects; Legionella pneumophila - genetics; Legionella pneumophila - growth & development; Legionnaires disease; Life Sciences; Microbial Viability - drug effects; Microbiology; Pathology; Polymerase Chain Reaction; Survival; Water Microbiology; Water monitoring; Yeasts; Esterase Activity; VBNC State; Dead Bacterium; Plumbing System; Total Organic Carbon
• ISSN: 0343-8651; 1432-0991
• DOI: 10.1007/s00284-008-9275-9

Legionella pneumophila,
a facultative intracellular human pathogen, can persist for long periods in natural and artificial aquatic environments. Eradication of this bacterium from plumbing systems is often difficult. We tested
L. pneumophila
survival after monochloramine treatment. Survival was monitored using the BacLight Bacterial Viability Kit (Molecular Probes), ChemChrome V6 Kit (Chemunex), quantitative polymerase chain reaction and culturability on buffered charcoal–yeast extract agar. In nonculturable samples, regain of culturability was obtained after addition of the amoeba
Acanthamoeba castellanii
, and esterase activity and membrane integrity were observed after >4 months after treatment. These results demonstrate for the first time that
L. pneumophila
could persist for long periods in biofilms into the viable but nonculturable (VBNC) state. Monitoring
L. pneumophila
in water networks is generally done by enumeration on standard solid medium. This method does not take into account VBNC bacteria. VBNC
L. pneumophila
could persist for long periods and should be resuscitated by amoeba. These cells constitute potential sources of contamination and should be taken into account in monitoring water networks.