Occurrence dePseudomonas aeruginosadans les réseaux intérieurs : présentation d’un protocole adapté à la collecte du biofilm présent dans la robinetterie sanitaire

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen that naturally occurs in aquatic environments. This bacterium is adapted to oligotrophic environmental conditions and could be detected in drinking water systems. Although, water for human consumption is required to be free of any bacteria that might pose a health risk, P. aeruginosa is not included in parameters to be analyse and in a recent report the ANSES conclude that there is no proof that the normal use of contaminated drinking water can be a source of infection by oral route in the general population. This bacterium is mostly harmless for healthy people but must be regarded as a relevant opportunistic pathogen for sensitive human population especially for hospitalized people in intensive care unit. This bacterium is responsible for almost 10% of the hospital-borne infections and drinking water network inside the building is suspected to be a source and a reservoir of P. aeruginosa . Although the target level to achieve is the absence of P. aeruginosa at terminal point-of-use, several studies showed that 4.5 in 97% of water samples taken in intensive care units are contaminated by P. aeruginosa . The origin of patients’ contamination remained discussed but among exogen sources of contamination, tap water is often suspected to be a source and a reservoir for these opportunistic pathogens. Nevertheless control strategies are limited for drinking water and recurrent contamination of tap water remained unsolved. Water contamination could be explained by retrograde contamination and by colonization of taps. To better characterize the populations of P. aeruginosa present in biofilm drinking water networks, we developed a protocol to sample biofilm from taps. Assays were performed on biofilms established inside taps and on the surface of tap swirls. Mechanical action of glass beads was compared with swabbing and proved to have more efficiency in sampling biofilm on surface of tap swirls. The protocol was then adapted to sample biofilm in faucets. It consists in filling the tap to study with a mixture of sterile distilled water and borosilicate glass beads of 1 mm in diameter and then to perform a mechanical shaking of 3 minutes with a vortex. This protocol will be used to collect biofilm on terminal point-of-use and to compare occurrence of P. aeruginosa in this type of biofilm and in the biofilm established on plumbing material.