Management and outcomes of Stenotrophomonas maltophilia recovered from deep-site clinical specimens: a bicentric retrospective cohort study

Background and objective Stenotrophomonas maltophilia is an emerging multidrug-resistant opportunistic pathogen, frequently recovered from deep sites in immunocompromised or critically ill patients. Its clinical relevance is difficult to distinguish from colonization, particularly in polymicrobial infections. To describe the management of patients with deep-site S. maltophilia isolates and to identify factors associated with 28-day mortality. Methods We conducted a bicentric retrospective study including all patients with at least one deep-site S. maltophilia isolates in two Paris academic hospitals between 2018 and 2020. Demographic, clinical, microbiological and therapeutic data were collected. Appropriate therapy was defined upon in vitro susceptibility. Propensity score weighting was applied to adjust for confounding when assessing the association between appropriate therapy and 28-day mortality. Results A total of 131 patients were included (67% male; median age 61 years); 63% were immunocompromised and 31% admitted to intensive care. Isolates originated mainly from urine (41%), blood (32%) and respiratory samples (21%); 57% of cultures were polymicrobial. Appropriate therapy was administered to 53% of patients, predominantly trimethoprim/sulfamethoxazole or fluoroquinolones. Overall 28-day mortality was 20%. Mechanical ventilation was independently associated with mortality (HR 4.13, P = 0.001). After propensity score weighting, appropriate therapy was not significantly associated with improved survival. Conclusion Targeted therapy against S. maltophilia did not reduce 28-day mortality after adjustment, suggesting that patient condition and infection severity may outweigh the effect of targeted treatment. Given the modest sample size, potential confounding, and the secondary nature of this analysis, these findings should be interpreted with caution. Careful clinical evaluation is warranted before initiating specific S. maltophilia therapy.