Student Research: Kathryn Brown

MS, , 1998
Faculty Advisor:

Public Health Significance of the Presence of Pseudomonas aeruginosa in a Municipal Water Distribution System


Pseudomonas aeruginosa is an opportunistic pathogen responsible for causing many nosocomial infections. This Gram-negative bacteria is considered ubiquitous and is found in several environments including water, soil, normal flora, and agricultural produce. Due to the increasing immunocomprimised population, there is a concern that exposure to municipal drinking water may be a route of transmission for P. aeruginosa infection. The goal of this study was to determine the impact of the presence of this opportunistic pathogen in Seattle drinking water on the Seattle patient population. This was accomplished by comparing the genetic fingerprints of the P. aeruginosa drinking water isolates to those of the patients' in the service area.

One thousand one hundred and thirty seven P. aeruginosa isolates from patients and water samples (raw, distribution, and hospital tap water) were ribotyped using PvuII restriction enzyme. The fingerprints were analyzed for shared ribotypes. A Yates-corrected chi-square test was used to compare the proportion of ribotype matches between Seattle patients and unexposed patients to Seattle drinking water. The results indicate that the Seattle drinking water is not a significant route of transmission for P. aeruginosa infections in the Seattle patient population. However, several of the hospital tap water samples hoarded hundreds of P. aeruginosa colonies, a characteristic not typically seen in tap water unless a biofilm is present in the upstream plumbing. Further investigation of the hospital water should be conducted to determine if the hospital water distribution system is colonized with pathogenic strains of P. aeruginosa.