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Post-Outbreak Investigation of Pseudomonas aeruginosa Faucet Contamination by Quantitative Polymerase Chain Reaction and Environmental Factors Affecting Positivity

Published online by Cambridge University Press:  20 July 2015

Emilie Bédard*
Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada INRS-Institut Armand-Frappier, Laval, QC, Canada
Céline Laferrière
Department of Microbiology and Immunology (Infection Control), CHU Ste-Justine, Université de Montréal, Montréal, QC, Canada
Dominique Charron
Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada
Cindy Lalancette
INRS-Institut Armand-Frappier, Laval, QC, Canada
Christian Renaud
Department of Microbiology and Immunology (Infection Control), CHU Ste-Justine, Université de Montréal, Montréal, QC, Canada
Nadia Desmarais
Nursing Care Division, CHU Ste-Justine, Montréal, QC, Canada
Eric Déziel
INRS-Institut Armand-Frappier, Laval, QC, Canada
Michèle Prévost
Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada
Address correspondence to: Emilie Bédard, NSERC Industrial Chair in Drinking Water, Polytechnique Montréal, P.O. Box 6079 Station Centreville, Montréal, QC, Canada, H3C 3A7 (



To perform a post-outbreak prospective study of the Pseudomonas aeruginosa contamination at the faucets (water, aerator and drain) by culture and quantitative polymerase chain reaction (qPCR) and to assess environmental factors influencing occurrence


A 450-bed pediatric university hospital in Montreal, Canada


Water, aerator swab, and drain swab samples were collected from faucets and analyzed by culture and qPCR for the post-outbreak investigation. Water microbial and physicochemical parameters were measured, and a detailed characterization of the sink environmental and design parameters was performed.


The outbreak genotyping investigation identified drains and aerators as the source of infection. The implementation of corrective measures was effective, but post-outbreak sampling using qPCR revealed 50% positivity for P. aeruginosa remaining in the water compared with 7% by culture. P. aeruginosa was recovered in the water, the aerator, and the drain in 21% of sinks. Drain alignment vs the faucet and water microbial quality were significant factors associated with water positivity, whereas P. aeruginosa load in the water was an average of 2 log higher for faucets with a positive aerator.


P. aeruginosa contamination in various components of sink environments was still detected several years after the resolution of an outbreak in a pediatric university hospital. Although contamination is often not detectable in water samples by culture, P. aeruginosa is present and can recover its culturability under favorable conditions. The importance of having clear maintenance protocols for water systems, including the drainage components, is highlighted.

Infect. Control Hosp. Epidemiol. 2015;36(11):1283–1291

Original Articles
© 2015 by The Society for Healthcare Epidemiology of America. All rights reserved 

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