Role of Stenotrophomonas maltophilia in hospital-acquired infection.

Stenotrophomonas maltophilia (previously Pseudomonas maltophilia, Xanthomonas maltophilia) is highly resistant to antibiotics. It causes infections that result in increased morbidity, but not usually mortality, in patients with weakened host defences. The increase in S. maltophilia nosocomial infections is due to the changing nature of the hospital patient population and to changes in antibiotic usage. Detection, identification and susceptibility testing methods require improvement, and this complicates the comparison of published data. Susceptibility testing should be reserved for those isolates that are clearly associated with disease. Treatment can be difficult and may be complicated by biofilm formation. S. maltophilia can both acquire and transfer resistance to antibiotics. Future therapeutic development may be directed against biofilms and efflux mechanisms, in order to render the organism more susceptible to available antimicrobial agents.