Tap water as a potential source of nosocomial Pseudomonas aeruginosa infections in an intensive care unit

Abstract number: P859

Barna Z., Antmann K., Pászti J., Németh M., Bánfi R., Vargha M.

Pseudomonas aeruginosa is a frequent cause of nosocomial infections in intensive care units. The water distribution system, tap and shower points of use may often serve as reservoirs for pseudomonads. If tap water is identified as the source of infections, appropriate preventive measures can be employed to reduce infection rates.

Aim of the present study was to assess the effect of point-of-use filters on

1Pseudomonas aeruginosa counts in tap water

2incidence of Pseudomonas spp. infections in an ICU

3clinical and environmental Pseudomonas spp. strains, in order to provide evidence for water-related infection.

The study was carried out in a 12 bed intensive care unit of a Hungarian hospital. Point-of-use filters (Pall Medical) were applied to all water outlets for 2 × 2 weeks. Tap water was sampled weekly before, during and after the use of the filters. Pseudomonas aeruginosa was enumerated according to ISO 12780 standard. Environmental Ps. aeruginosa strains were isolated from tap water and compared to clinical isolates by serology, phage and antibiotic resistance profile, pyocin production pattern and total genome restriction pulse field gel electrophoresis (PFGE).

Three of five tap outlets were found to be initially colonised by Ps. aeruginosa (1–300 CFU/L). Application of the point-of-use filters eliminated Ps. aeruginosa as well as other waterborne bacteria from the tap water during the two weeks of usage (as specified by the manufacturer). After the removal of the filters, Pseudomonas spp. counts within the water samples returned to the levels initially detected.

There were no new clinical cases of Pseudomonas infections identified during the use of the filters, whereas an average of 6 cases/month was recorded during the preceding 2 years.

Clinical (13) and environmental (101) strains were collected and identified in the study period. Environmental isolates clustered into two groups by all of the employed typing methods; serotypes O1 and O17 were discerned. All strains (including clinical isolated) had identical antibiotic resistance profile, all were sensitive to b-lactames. PFGE profiles of the clinical isolates showed high similarity to the environmental strains.

In conclusion, typing results supported the hypothesis that tap water and/or taps are likely reservoirs of infective strains. Point-of-use filters were found to be effective means for the infection control of pseudomonads.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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