Rapid detection and enumeration of Legionella pneumophila in hot water systems by solid-phase cytometry.
A new method for the rapid and sensitive detection of Legionella pneumophila in hot water systems has been developed. The method is based on an IF assay combined with detection by solid-phase cytometry. This method allowed the enumeration of L. pneumophila serogroup 1 and L. pneumophila serogroups 2 to 6, 8 to 10, and 12 to 15 in tap water samples within 3 to 4 h. The sensitivity of the method was between 10 and 100 bacteria per liter and was principally limited by the filtration capacity of membranes. The specificity of the antibody was evaluated against 15 non-Legionella strains, and no cross-reactivity was observed. When the method was applied to natural waters, direct counts of L. pneumophila were compared with the number of CFU obtained by the standard culture method. Direct counts were always higher than culturable counts, and the ratio between the two methods ranged from 1.4 to 325. Solid-phase cytometry offers a fast and sensitive alternative to the culture method for L. pneumophila screening in hot water systems.
Centre National de Référence des Legionella, INSERM E-0230, Laboratoire de Bactériologie, Faculté de Médecine Laennec IFR 62, 69372 Lyon, France.
Helena
H
Aurell
Philippe
P
Catala
Pierre
P
Farge
France
F
Wallet
Matthieu
M
Le Brun
Jürgen H
JH
Helbig
Sophie
S
Jarraud
Philippe
P
Lebaron
D015169:Colony Count, Microbial / Q000379:methods* / Q000706:statistics & numerical data; D005455:Fluorescent Antibody Technique; D006358:Hot Temperature; D016952:Legionella pneumophila / Q000276:immunology / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D013045:Species Specificity; D013194:Staining and Labeling / Q000379:methods; D014871:Water Microbiology