Molecular epidemiology ofPseudomonas aeruginosain an intensive care unit

Abstract

SUMMARYGenotyping was used to analysePseudomonas aeruginosaisolates from sink drains and 15 intubated patients as part of a 3-month prospective study of strain transmission in a medical-surgical intensive care unit. Ninety percent of all washbasin drains were persistently contaminated with severalP. aeruginosagenotypes. In 60% (9/15) of the patients,P. aeruginosacolonization or infection was hospital-acquired:P. aeruginosastrains isolated from these patients were present in hospital sinks or in other patients before their admission. Since all patients were immobile, personnel were the probable route of transmission ofP. aeruginosain the hospital. The mechanism of strain transmission from sinks to hands during hand washing was investigated in a children's hospital. WhenP. aeruginosawas present at densities of > 105/c.f.u. per ml in sink drains, hand washing resulted in hand contamination withP. aeruginosavia aerosol generation in the majority of experiments orP. aeruginosawas detected using an air sampler above the washing basin. HighP. aeruginosacfu were present at 4.30 h in the eight sinks (5.4 × 105−7.0 × 1010c.f.u./ml), whereas at 13.00 hP. aeruginosac.f.u. were significantly lower (3.1 × 102−8.0 × 105c.f.u. / ml). These data reveal that the danger of bacterial contamination of hands during hand washing is highest in the morning. The identified transmission routes demand more effective hygienic measures in hospital settings particularly concerning personnel hands and sink drains.