Real-world, multicentre evaluation of the incidence and risk factors for non-susceptible Stenotrophomonas maltophilia isolates.

BACKGROUND: Stenotrophomonas maltophilia is a cause of infection most commonly in the opportunistic host. Trimethoprim-sulfamethoxazole and levofloxacin are considered first-line treatment agents. With reports of increasing resistance to these first-line agents, it is important to determine risk factors associated with a non-susceptible isolate. METHODS: This was a real-world, multicentre, retrospective case-control study from five centres in the southeast United States evaluating S. maltophilia. The primary outcome was risk factors associated with non-susceptibility of S. maltophilia isolates to ≥1 antimicrobial agents. Secondary outcomes include incidence of S. maltophilia non-susceptibility, all-cause mortality, and 30-day readmission rates. RESULTS: There were 325 patients included in the study. For the primary outcome, the only factor associated with non-susceptibility per univariate analysis was isolation from urine culture (13.3% vs. 5.4%; P = 0.014), whereas the presence of mechanical ventilation (37.7% vs. 21.5%) and intensive care unit admission (35.3% vs. 18.4%) were associated with susceptibility (P < 0.001). For the secondary outcomes, non-susceptibility was present in 49% of isolates with 43 of 325 (13.2%), 53 of 324 (16.4%), and 105 of 172 (61%) to TMP-SMX, levofloxacin, and ceftazidime, respectively. Resistance to chloramphenicol and tigecycline was observed among 5/26 and 11/16 of tested isolates, respectively. Sixty-six patients (20%) experienced all-cause, inpatient mortality (18% susceptible vs. 23% non-susceptible; P = 0.280) and 44 patients (17%) were readmitted within 30 days of discharge (16% susceptible vs. 18% non-susceptible; P = 0.673). CONCLUSION: S. maltophilia non-susceptibility had a prevalence of ∼50% to at least one first-line or commonly used agent. More research is needed to delineate risk factors for non-susceptible isolates.