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Are two really better than one? A retrospective study comparing monotherapy versus combination therapy for Stenotrophomonas maltophilia infections

Harris N, Mackowiak A, Wrenn RH, Lee H-J, Reed A, Erkanli A, Turner NA, Moehring R et al.

Microbiology spectrum, 2026

370 participants

Abstract

Management of Stenotrophomonas maltophilia infections is challenging. The Infectious Diseases Society of America recommends up-front combination therapy, though this may increase toxicity without clear benefit. We compared combination therapy (CT) versus monotherapy (MT) in the management of S. maltophilia infections to inform institutional decision-making and microbiology reporting. We conducted a retrospective study of adults with S. maltophilia infections who received ≥72 h of organism-directed, in vitro active therapy between July 1, 2019, and November 30, 2024. Patients were excluded if they lacked evidence of infection, had cystic fibrosis, or had polymicrobial cultures. CT was defined as more than one agent given concomitantly for ≥72 h. The primary outcome was clinical failure, a composite of 30-day all-cause mortality and microbiologically confirmed recurrence. Of 370 patients screened, 103 met the inclusion criteria (86 MT and 17 CT). CT recipients were more often immunocompromised (70.6% vs 22.1%) with bacteremia (58.8% vs 19.8%). Clinical failure occurred in 47.1% versus 36.0% of patients in the CT and MT cohorts, respectively (RD: 15.6%; 95% CI: -9.9% to 41.2%). Resistance developed in 8.7% of isolates, most commonly with levofloxacin. Adverse effects occurred in 26.7% MT and 35.3% CT cohorts. We observed no differences in clinical failure between CT versus MT for the management of S. maltophilia infections. Risks of adverse effects with CT should be balanced…

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: 370 participants or records.

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