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Risk factors and outcomes associated with difficult-to-treat resistance in Stenotrophomonas maltophilia: A clinical and microbiological hospital-based cohort study

P. Ross, K. Allel, Vicente Gándara, G. Peralta, F. Caro, C. Castillo, J. Jiménez, Jorge Miles et al.

Epidemiology and Infection, 2026

101 participants

Abstract

Abstract We aimed to comprehensively assess Stenotrophomonas maltophilia infections, examining their incidence and clinical and microbiological characteristics in a tertiary hospital between 2021 and 2023. Primary outcomes were 30-day mortality and desirability-of-outcome ranking (DOOR). S. maltophilia incidence rose from 0.38 in 2017 to 2.66 cases/1000 patient-days in 2023, correlated with carbapenem consumption (rho = 0.90, p = 0.04). The cohort included 101 patients (median age of 61 years, IQR 43–71); 63% were male patients, 91% admitted in ICU, predominantly with lower respiratory tract infections (75%). Difficult-to-treat resistance (DTR) was identified in 14% of the isolates and associated with previous trimethoprim–sulfamethoxazole (TMP–SMX) use (aOR 23.15, 95% CI 3.67–145.77). Thirty-day mortality was 25% and associated with invasive mechanical ventilation (aOR 5.80, 95% CI 1.03–32.63), while appropriate definitive therapy was protective (aOR 0.01, 95% CI <0.01–0.16). Worse DOOR outcomes were associated with levofloxacin-resistant isolates (69.3%, CI 55.9%–80.9%) and inappropriate definitive treatment (81.1%, 95% CI 68.2%–90.8%). Overall, S. maltophilia has emerged as a relevant carbapenem-resistant gram-negative bacteria, with a high frequency of DTR phenotypes associated with previous TMP–SMX exposure. Appropriate therapy and levofloxacin susceptibility were linked to better outcomes.

How strong is the evidence?

Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 101 participants or records.

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