Risk factors for infections with multidrug-resistant Stenotrophomonas maltophilia in patients with cancer

BACKGROUND. Stenotrophomonas maltophilia is responsible for an increasing number of infections, especially in hospitalized patients. Therapy options are limited and trimethoprim/sulfamethoxazole (TMP/SMX) is often the main treatment option for this infection. In the current study, the risk factors were determined for the emergence of multidrug-resistant (MDR) S. maltophilia. METHODS. A case-control study was conducted to determine risk factors for the development of MDR S. maltophilia in cancer patients. The case group was composed of patients treated at the University of Texas M. D. Anderson Cancer Center for MDR S. maltophilia between 1996 and 2004 (n = 54). Two control groups were used: patients at comparable risk for S. maltophilia (C-controls) and patients with S. maltophilia infection that was susceptible to TMP-SMX and at least 2 other antibiotics (ciprofloxacin, ceftazidime, amikacin, and ticarcillin/clavulanate) (S-controls). RESULTS. When compared with C-controls, prior use of carbapenems or quinolones and admission to an intensive care unit within 30 days of isolation of the pathogen were found to be independently associated with MDR S. maltophilia infection (P <.02), as was an increased overall mortality rate (P =.04). When compared with S-controls, risk factors were history of S. maltophilia infection during the prior year and prior use of TMP-SMX (P =.015). CONCLUSIONS. Judicious use of TMP-SMX, carbapenems, and quinolones is necessary to control the risk for MDR S. maltophilia infection.