Cross-colonisation with Pseudomonas aeruginosa of patients in an intensive care unit
- Dennis C J J Bergmansa,
- Marc J M Bontenb,
- Frank H van Tielc,
- Carlo A Gaillardd,
- Siebe van der Geesta,
- Rob M Wiltinga,
- Peter W de Leeuwa,
- Ellen E Stobberinghc
- aDepartment of Internal Medicine, University Hospital Maastricht, Maastricht, The Netherlands, bDepartment of Internal Medicine, University Hospital Utrecht, Utrecht, The Netherlands, cDepartment of Medical Microbiology, University Hospital Maastricht, Maastricht, The Netherlands, dDepartment of Internal Medicine, Eemland Hospital, Amersfoort, The Netherlands
- Dr D C J J Bergmans, Department of Internal Medicine, University Hospital Maastricht, P.O. Box 5800, 6202 AZ Maastricht, The Netherlands.
- Received 9 February 1998
- Revision requested 18 May 1998
- Revised 17 June 1998
- Accepted 6 July 1998
Abstract
BACKGROUND Ventilator-associated pneumonia (VAP) caused by Pseudomonas aeruginosa is usually preceded by colonisation of the respiratory tract. During outbreaks, colonisation with P aeruginosa is mainly derived from exogenous sources. The relative importance of different pathways of colonisation of P aeruginosa has rarely been determined in non-epidemic settings.
METHODS In order to determine the importance of exogenous colonisation, all isolates of P aeruginosa obtained by surveillance and clinical cultures from two identical intensive care units (ICUs) were genotyped with pulsed field gel electrophoresis.
RESULTS A total of 100 patients were studied, 44 in ICU 1 and 56 in ICU 2. Twenty three patients were colonised with P aeruginosa, seven at the start of the study or on admission and 16 of the remaining 93 patients became colonised during the study. Eight patients developed VAP due to P aeruginosa. The incidence of respiratory tract colonisation and VAP with P aeruginosa in our ICU was similar to that before and after the study period, and therefore represents an endemic situation. Genotyping of 118 isolates yielded 11 strain types: eight in one patient each, two in three patients each, and one type in eight patients. Based on chronological evaluation and genotypical identity of isolates, eight cases of cross-colonisation were identified. Eight (50%) of 16 episodes of acquired colonisation and two (25%) of eight cases of VAP due to P aeruginosa seemed to be the result of cross-colonisation.
CONCLUSIONS Even in non-epidemic settings cross-colonisation seems to play an important part in the epidemiology of colonisation and infection with P aeruginosa.
