Genomic and Phenotypic Insights into Carbapenem-Resistant Pseudomonas aeruginosa in the Aquatic Environments of the Tibetan Plateau.

Carbapenem-resistant Pseudomonas aeruginosa is increasingly becoming a global health threat. However, although aquatic environments are key resistance reservoirs, data obtained from high-altitude ecosystems are scarce. Whole-genome sequencing of eight carbapenem-resistant P. aeruginosa isolates collected from aquatic environments in the Tibetan Plateau identified three sequence types (STs), with ST1420 predominating (62.5%, 5/8). Phylogenetic analysis revealed a close clustering of isolates with those from distant clinical settings, suggesting potential cross-habitat transmission. All studied strains were multidrug-resistant, exhibiting 100% resistance to imipenem, ceftriaxone, and trimethoprim-sulfamethoxazole. This included the PA6 strain, which showed multiple-antibiotic resistance. Eight strains harbored the intrinsic carbapenemase gene blaOXA-50. The diverse virulence-gene profiles of strains PA2, PA4, and PA6 aligned with their high pathogenicity observed both in vitro and in vivo. However, virulence genotypes sometimes did not correlate with phenotypes, revealing the limitations of relying on static genetic information alone. This study highlights the aquatic environments of the Tibetan Plateau as reservoirs of carbapenem-resistant P. aeruginosa with substantial genetic diversity and divergent pathogenic potential, underscoring their public-health relevance.