Phenotypic and genomic characterization of a blaOXA-181-producing ST656 Klebsiella pneumoniae isolate from China.
Carbapenem-resistant Klebsiella pneumoniae (CRKP) has emerged as a major global health threat due to its rapid dissemination and severely limited treatment options. Here, we report the phenotypic and genomic characterization of an ST656 K. pneumoniae clinical isolate carrying blaOXA-181 in China. Antimicrobial susceptibility testing confirmed carbapenem resistance, whereas the isolate remained susceptible to aztreonam, amikacin and trimethoprim/sulfamethoxazole, with a colistin MIC of ≤0.5 μg/mL. Whole-genome sequencing identified the blaOXA-181 gene on a 51,391-bp ColKP3/IncX3 plasmid co-harboring multiple resistance determinants. Conjugation assays yielded blaOXA-181 -positive transconjugants at a recovery frequency of 2 × 10-4. Following serial passage, blaOXA-181 was stably maintained for 100 generations. Comparative genomic analysis showed that the blaOXA-181-carrying plasmid shared a highly conserved backbone with plasmids from geographically diverse isolates, while KP413706 represents a distinct ST656 lineage. These findings expand the genomic evidence for blaOXA-181-carrying ST656 K. pneumoniae in China and underscore the urgent need for enhanced genomic surveillance and stringent infection control strategies.