Combination of Heat Shock and Enhanced Thermal Regime to Control the Growth of a Persistent Legionella pneumophila Strain.
Following nosocomial cases of Legionella pneumophila, the investigation of a hot water system revealed that 81.5% of sampled taps were positive for L. pneumophila, despite the presence of protective levels of copper in the water. A significant reduction of L. pneumophila counts was observed by culture after heat shock disinfection. The following corrective measures were implemented to control L. pneumophila: increasing the hot water temperature (55 to 60 °C), flushing taps weekly with hot water, removing excess lengths of piping and maintaining a water temperature of 55 °C throughout the system. A gradual reduction in L. pneumophila counts was observed using the culture method and qPCR in the 18 months after implementation of the corrective measures. However, low level contamination was retained in areas with hydraulic deficiencies, highlighting the importance of maintaining a good thermal regime at all points within the system to control the population of L. pneumophila.
Department of Civil Engineering, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada. emilie.bedard@polymtl.ca.
Emilie
E
Bédard
Department of Civil Engineering, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada. ines.boppe@polymtl.ca.
Inès
I
Boppe
CIUSSSE-Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC J1G 2E8, Canada. skouame.chus@ssss.gouv.qc.ca.
Serge
S
Kouamé
Department of Microbiology and Infectious Diseases, Université de Sherbrooke, QC J1K 2R1, Canada. Philippe.Martin@USherbrooke.ca.
Philippe
P
Martin
CIUSSSE-Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC J1G 2E8, Canada. linda.pinsonneault@usherbrooke.ca.
Linda
L
Pinsonneault
Department of Microbiology and Infectious Diseases, Université de Sherbrooke, QC J1K 2R1, Canada. Louis.Valiquette@USherbrooke.ca.
Louis
L
Valiquette
CIUSSSE-Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC J1G 2E8, Canada. jracine.chus@ssss.gouv.qc.ca.
Jules
J
Racine
Department of Civil Engineering, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada. michele.prevost@polymtl.ca.
Michèle
M
Prévost
Legionella pneumophila; copper concentration; culture; hospital premise plumbing; legionellosis; quantitative polymerase chain reaction; sanitary hot water; temperature diagnostic