Optimizing therapy for Stenotrophomonas maltophilia.

Stenotrophomonas (Xanthomonas) maltophilia is a nonfermentative, gram-negative bacillus that is widely distributed in natural and human-made environments. In the nonhospital setting it is an uncommon pathogen, typically causing soft tissue infection of contaminated wounds. In the hospital setting, particularly among critical care and oncology patients, S. maltophilia may cause catheter-related bacteremia, pneumonia, soft tissue infection, meningitis, prosthetic valve endocarditis, and ocular infections. S. maltophilia is usually resistant to multiple antimicrobials, including expanded-spectrum penicillins, third-generation cephalosporins, carbapenems, aminoglycosides, and quinolones. Trimethoprim-sulfamethoxazole is the antimicrobial agent of choice for this pathogen but is bacteriostatic. Further, resistance to this agent is increasing. Certain combinations of antibiotics are synergistic and may be appropriate for patients harboring resistant organisms or with life-threatening infections.