RISK-FACTORS ASSOCIATED WITH ISOLATION OF STENOTROPHOMONAS (XANTHOMONAS) MALTOPHILIA IN CLINICAL SPECIMENS

OBJECTIVE: To determine risk factors for patients whose cultures grew Stenotrophomonas maltophilia. DESIGN: Retrospective case-control study of 60 patients with cultures positive for S maltophilia, matched by s pecimen site to 120 controls whose cultures grew other gram-negative a erobic bacteria. SETTING: University medical center. RESULTS: S maltop hilia was identified from the following sites: respiratory (36), wound (13), urinary (6), blood (4), and cerebral spinal fluid (1). By univa riate analysis, cases had a higher risk of exposure than controls for ampicillin (P<.001), gentamicin (P<.001), vancomycin (P=.001), metroni dazole (P=.003), piperacillin (P=.007), cefotaxime (P=.014), ceftazidi me (P=.017), ciprofloxacin (P=.030), tobramycin (P=.040), and chronic respiratory disease (P=.024). Length of time foreign objects were in p lace prior to positive culture differed significantly between cases an d controls only for endotracheal tubes in patients with respiratory is olates (median number of days: 12.5 for cases, 5 for controls; P=.007) . For patients with urinary tract infections, having a urinary cathete r increased the odds of infection 10 times over controls. Exposures fo und by multivariate analysis to be significantly more prevalent in cas es than controls included ampicillin, cefotaxime, erythromycin, gentam icin, metronidazole, piperacillin, tobramycin, chronic respiratory dis ease, and female gender. Odds ratios were >1 indicating higher risk fo r cases, except for erythromycin, which had an odds ratio <1. CONCLUSI ONS: The primary risk factor associated with isolation of S maltophili a was antibiotic use. For patients with pulmonary infections, chronic respiratory disease and length of time an endotracheal tube was in pla ce also contributed to the risk. This suggests that judicious use of a ntibiotics may prevent some cases of S maltophilia infection.