Stenotrophomonas maltophilia infections - Biofilm-mediated virulence, multidrug resistance, clinical impact, and emerging treatment strategies: A review.

Stenotrophomonas maltophilia is an opportunistic, multidrug-resistant (MDR), Gram-negative bacterium that has emerged as an important cause of hospital- and community-acquired infections, particularly in immunocompromised, critically ill, and hospitalized patients. Its increasing clinical relevance is driven by extensive virulence determinants, biofilm formation, intrinsic and acquired antimicrobial resistance, and persistence within healthcare-associated environmental reservoirs. This narrative review summarizes current evidence on the epidemiology, pathogenic mechanisms, antimicrobial resistance, and therapeutic management of S. maltophilia, with a particular focus on emerging treatment strategies. A literature search of PubMed, Scopus, Web of Science, and Google Scholar was performed to identify relevant studies published between 1997 and 2026. The available evidence demonstrates that biofilm formation, quorum sensing, adhesion factors, secretion of extracellular enzymes, and multiple resistance mechanisms-including β-lactamases, multidrug efflux pumps, and horizontally acquired resistance genes-substantially contribute to persistent infections and therapeutic failure. Hospital outbreaks are frequently associated with contaminated water systems, sinks, and medical devices, emphasizing the importance of environmental surveillance and infection control. Trimethoprim-sulfamethoxazole (TMP-SMX) remains the recommended first-line therapy, whereas minocycline, tigecycline, fluoroquinolones, and cefiderocol represent important alternatives for selected patients. Emerging approaches, including novel tetracyclines, bacteriophages, bacteriocins, ceragenins, anti-biofilm agents, and plant-derived compounds, have demonstrated promising preclinical activity against MDR and biofilm-associated infections, although robust clinical evidence remains limited. Continued surveillance, antimicrobial stewardship, pharmacokinetic/pharmacodynamic-guided therapy, and well-designed prospective clinical studies are essential to optimize the management of S. maltophilia infections and facilitate the translation of emerging therapeutic strategies into clinical practice.