Bacteremia due to Stenotrophomonas maltophilia in patients with hematologic malignancies

Predisposing factors, clinical characteristics, and antimicrobial treatment of 37 hematology patients with Stenotrophomonas maltophilia bacteremia who were seen at the department of hematology of the University La Sapienza (Rome) from 1987 to 1996 were evaluated. The results were compared with a control group of patients with Pseudomonas aeruginosa bacteremia. Profound neutropenia was more prolonged in the S. maltophilia group (P = .025), severe cellulitis occurred only in S. maltophilia-infected patients (11 [30%]; P = .0002), and the bacteremia presented as breakthrough infection in 56% of the cases due to S. maltophilia (vs. only 24% of those due to P. aeruginosa; P = .002). Acute mortality rates associated with S. maltophilia and P. aeruginosa bacteremia were 24% and 21%, respectively. In both groups, profound neutropenia and hypotension at the onset of bacteremia, duration of profound neutropenia during bacteremia, severity-of-illness score ≥4, and inappropriate antibacterial treatment were factors significantly associated with death. Most S. maltophilia isolates were resistant to aminoglycosides, β-lactams, and ciprofloxacin. Cotrimoxazole and ticarcillin-clavulanic acid showed borderline activity. Prompt administration of in vitro-active antibiotics may improve the prognosis of S. maltophilia bacteremia, especially for immunocompromised patients, and novel drug combinations are needed for the treatment of severe infections.