Infections caused by Stenotrophomonas maltophilia--a prospective study.

BACKGROUND: Stenotrophomonas maltophilia is an opportunistic microorganism, often highly resistant to routinely tested antibiotics. This microorganism is isolated in specimens from patients with nosocomial infections with increasing frequency.

PATIENTS AND METHODS: During a 1-year period (1998/1999) S. maltophilia was isolated from 137 specimens (0.26% of all investigated specimens) from 80 patients who were treated in a 1,500 bed major tertiary care teaching hospital in Leipzig. The data of 76 patients (133 specimens) could be collected and analyzed completely.

RESULTS: The pathogen was most frequently detected in specimens from the respiratory tract (54%). In five patients (six cases) S. maltophilia was isolated from blood cultures (0.3% of all positive blood cultures; 1.4% of all gram-negative isolates from blood cultures). 70 of the infected patients were inpatients and 32 (42%) of them were treated on the internal medicine wards. Of these 32 patients only six (19%) were pretreated with imipenem. The Length of stay at the hospital resulted in an independent increased risk of infection with S. maltophilia. In addition, this organism was detected in six infected outpatients.

CONCLUSION: S. maltophilia is not only a nosocomial pathogen. Pretreatment with a carbapenem is no longer an unequivocal risk factor for an infection with S. maltophilia.