High-risk clones of Pseudomonas aeruginosa contaminate the drinking water networks of French cities

Pseudomonas aeruginosa is a major opportunistic pathogen responsible for severe infections in immunocompromised patients. The contamination of drinking water networks (DWNs) with this pathogen is underestimated, as it is mostly in the state of persister cells undetected by the recommended monitoring technique. We collected water samples from eight cities distant from each other and searched for P. aeruginosa using a culture-based method that resuscitates persister cells. The genomes of isolates were sequenced. Five DWNs of the eight tested (62.5%) were contaminated with P. aeruginosa, of which four were contaminated with high-risk clones (ST308, ST395). Surprisingly, the ST308 isolates retrieved from the four independent and distant DWNs were clonal. Most P. aeruginosa isolates shared a genomic island conferring tolerance to copper-ions. The population structure of the collection may result from both a common source of contamination by plumbing supplies and the selection of clones sharing genetic elements that presumably aided their propagation in DWNs.