MOLECULAR EPIDEMIOLOGY OF PSEUDOMONAS-AERUGINOSA IN AN INTENSIVE-CAREUNIT

Genotyping was used to analyse Pseudomonas aeruginosa isolates from si nk drains and 15 intubated patients as part of a 3-month prospective s tudy of strain transmission in a medical-surgical intensive care unit. Ninety percent of all washbasin drains were persistently contaminated with several P. aeruginosa genotypes. In 60% (9/15) of the patients, P. aeruginosa colonization or infection was hospital-acquired: P. aeru ginosa strains isolated from these patients were present in hospital s inks or in other patients before their admission. Since all patients w ere immobile, personnel were the probable route of transmission of P. aeruginosa in the hospital. The mechanism of strain transmission from sinks to hands during hand washing was investigated in a children's ho spital. When P. aeruginosa was present at densities of > 10(5)/c.f.u. per ml in sink drains, hand washing resulted in hand contamination wit h P. aeruginosa via aerosol generation in the majority of experiments or P. aeruginosa was detected using an air sampler above the washing b asin. High P. aeruginosa cfu were present at 4.30 h in the eight sinks (5.4 x 10(5)-7.0 x 10(10) c.fu./ml), whereas at 13.00 h P. aeruginosa c.fu. were significantly lower (3.1 x 10(2)-8.0 x 10(5) c.f.u./ml). T hese data reveal that the danger of bacterial contamination of hands d uring hand washing is highest in the morning. The identified transmiss ion routes demand more effective hygienic measures in hospital setting s particularly concerning personnel hands and sink drains.