Genetic Diversity of Stenotrophomonas maltophilia and Clonal Transmission (ST92) in Critical Care Units at Hospital Juárez de México: MLST and Virulence Profiling.

Stenotrophomonas maltophilia is considered one of the emerging bacterial agents causing healthcare-associated infections (HAIs) in hospital environments. This microorganism has been identified as multidrug-resistant, capable of forming mature biofilms-an ability that promotes adherence to surfaces and invasive medical devices, favoring persistence in hospital environments and the potential to generate outbreaks. The aim of this study was to characterize S. maltophilia strains isolated from HAI cases at the Hospital Juárez de México and to determine the presence of hidden outbreaks. Antibiotic resistance profiles were determined, along with the typing of 20 genes associated with virulence factors and the assessment of the ability to form mature biofilms on inert surfaces. Finally, sequence type (ST) was obtained through multilocus sequence typing (MLST) analysis, and a phylogenetic tree was constructed to determine the clonal diversity of the isolates. All strains showed uniform resistance to β-lactam antibiotics tested while remaining sensitive to fluoroquinolones, phenicols, tetracyclines, and trimethoprim/sulfamethoxazole. Some isolates exhibited adherent activity, with the "strong biofilm-former" phenotype predominating. Sixteen virulence-related genes were heterogeneously detected, revealing broad genetic diversity. MLST analysis grouped the isolates into nine ST related to infection cases reported in others countries. Phylogenetic analyses demonstrated the presence of three potential clones distributed across Internal Medicine and the Pediatric Intensive Care Unit. These results highlight the importance of investigating S. maltophilia as an HAI-associated pathogen that remains understudied.