[Nosocomial Stenotrophomonas maltophilia infections in a university hospital].

Stenotrophomonas maltophilia is a nosocomial pathogen of increasing importance. In our study, 190 S. maltophilia strains isolated from 153 hospitalized patients between January 2000-April 2004, at Farabi Hospital at Medical School of Karadeniz Technical University, were prospectively evaluated. Of these patients 67.9% were clinically compatible with nosocomial infection, and 32% were considered as colonization. It was observed that rate of infection had a tendency to increase one year of age and above 50 years of age. Nosocomial infection and/ or colonization with S. maltophilia was detected in 19.7 +/- 15.2 (1-89) days after hospitalization. The clinical manifestations were bacteremia (36.5%), pneumoniae (28.8%), urinary system infection (12.5%), surgical site infection (11.5%) and peritonitis (6.7%). The bacteremia episodes were associated with central venous catheter in 37.3% (19/51), ventilator associated pneumonia in 11.7% (6/51), urinary system infection in 7.8% (4/51), peritonitis in 3.9% (2/51), and surgical site infection in 1.9% (1/51) of cases. Nineteen patients (37.3%) had no apparent primary source of infection. Higher APACHE II score, longer duration of hospitalization and prior extended-spectrum antibiotic therapy were observed in most of the patients. Antibiotic susceptibility testing revealed that, the most effective antibiotics against the isolates were trimethoprim-sulfamethoxazole (94%), ticarcillin/clavulanate (79%) and ciprofloxacin (53.5%). Crude mortality rate in the patients with S. maltophilia infections was found to be 25%. In addition, it was observed that proper antibiotic treatment had protective role against mortality (14.6% vs 63.6%; OR = 0.1, Cl95 0.12-0.42, P = 0.000). It can be concluded that to prevent infections due to S. maltophilia , effective infection control programmes and rational antibiotic use policies should be established promptly.