Phenotypic and genomic characterization of tigecycline-insensitive Klebsiella pneumoniae strains and validation of highly virulent MDR strains

Our study revealed a high proportion (21%) of tigecycline-insensitive K. pneumoniae (TIKP) strains. We further characterized these TIKP isolates phenotypically and genomically, confirming the presence of highly virulent multidrug-resistant (MDR) strains. We discovered a novel allele (phoE 813) and a novel ST (8597). Our findings are significant because phenotypic analysis of TIKP allows clear determination of the level of tigecycline resistance (TRKP), which aids in optimizing antibiotic therapy and supports more rational clinical drug use. In addition, the plasmid-mediated resistance genes (e.g., the concurrent presence of both mcr-8 and tmexCD-toprJ in strain 10 in this study) may spread through the environmental-animal-human transmission chain. These results provide valuable insights for developing strategies to monitor and control the spread of TIKP.