Genomic Characterization and Antimicrobial Resistance Determinants of Clinical Stenotrophomonas maltophilia Isolates from Lebanon
Stenotrophomonas maltophilia is an emerging multidrug-resistant opportunistic pathogen associated with high morbidity in hospitalized patients. This study presents the comprehensive genomic characterization of 57 clinical S. maltophilia isolates collected from a tertiary care hospital in Lebanon. Wh...
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| Format: | masterThesis |
| Published: |
2025
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| Online Access: | http://hdl.handle.net/10725/16995 https://doi.org/10.26756/th.2023.782 http://libraries.lau.edu.lb/research/laur/terms-of-use/thesis.php |
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| Summary: | Stenotrophomonas maltophilia is an emerging multidrug-resistant opportunistic pathogen associated with high morbidity in hospitalized patients. This study presents the comprehensive genomic characterization of 57 clinical S. maltophilia isolates collected from a tertiary care hospital in Lebanon. Whole-genome sequencing (WGS) and bioinformatic analyses were conducted to determine antimicrobial resistance profiles, virulence factors, and mobile genetic elements. Multilocus sequence typing (MLST) revealed high genetic diversity, with isolates distributed across 12 known sequence types (STs), and over half (56%) assigned to novel or untypeable STs. Five isolates (ST138) were recovered from respiratory samples in critical care units, suggesting potential nosocomial transmission. Resistance to key antimicrobials was observed: 28.1% of isolates were resistant to levofloxacin, 3.5% to trimethoprim-sulfamethoxazole (TMP-SMX), and 71.9% to colistin. While TMP-SMX resistance was limited, it was not always linked to common resistance genes (e.g., sul1, sul2), suggesting alternative mechanisms. Similarly, fluoroquinolone resistance was only partially associated with the presence of smeD, pointing to multifactorial resistance pathways. Genomic screening showed that all isolates harbored the efflux pump genes phoP, macA, macB, emrA, and emrB, which may contribute to intrinsic resistance. Virulence-related genes such as fliC, smf-1, and katA were widely distributed, while biofilm assays revealed phenotypic heterogeneity despite conserved genetic markers. Seventeen isolates carried Tn3-family transposons associated with metal resistance genes, emphasizing the role of mobile genetic elements in adaptation and survival. These findings reveal the complexity of S. maltophilia as a nosocomial pathogen and highlight the need for further functional studies to elucidate resistance mechanisms. Enhanced molecular surveillance and targeted infection control strategies are critical to managing the spread of this highly adaptable organism in healthcare settings. |
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