Analysis of transmission pathways of Pseudomonas aeruginosa between patients and tap water outlets*

Abstract

To study the association between infection and faucet contamination in a surgical intensive care unit (SICU). Prospective cohort study. One SICU and 12 peripheral wards. From 45 patients colonized or infected with P. aeruginosa, 87 positive isolates were collected. P. aeruginosa also was found in 150 of 259 (58%) tap water samples taken from patient rooms. Clonal relationships between patient and tap water isolates were established by random amplification of polymorphic DNA-polymerase chain reaction. A long-time contamination (144 wks) with a single specific genotype for each of the faucets in our SICU was observed. Additional genotypes found in tap water from these faucets were only isolated over short periods of time. P. aeruginosa was shown to reside in single faucets and did not originate from the supplying mains. In 15 of 45 patients (33%), P. aeruginosa genotypes were identical to those from the faucets in the patient rooms. In six other patients, the same genotype was found in faucets from neighboring rooms. Faucets served as the source of infection for patients in 35% of cases, and on the other hand a retrograde contamination of faucets by patients was observed in 15% of cases. Tap water from faucets contaminated with P. aeruginosa plays an important role in the propagation of this pathogen among patients. A high number of transmissions were shown to occur both from faucet to patient and from patient to faucet. Our SICU served as an epicenter for the spread of P. aeruginosa to peripheral wards. It appears prudent to follow strict hygienic precautions such as wearing gloves and performing thorough alcoholic rub disinfection of hands after patient care and after hand washing at locations known to harbor.