Acquisition and Transmission of tmexCD1-toprJ1-Positive Plasmids in Clinical ST17 Klebsiella pneumoniae.

Purpose: It is well known that bacteria often acquire drug resistance genes through acquiring exogenous resistant plasmids. The tmexCD1-toprJ1-positive plasmid confers tigecycline resistance to bacterial strains. Methods: Three sequence type (ST) 17 Klebsiella pneumoniae strains were isolated from two patients within 5 days. Experimental and comparative genomic analyses were performed to investigate potential transmission routes and antimicrobial resistance phenotype disparities. Results: Strain HD9931 was tigecycline-sensitive, whereas HD9932 and HD10868 were tigecycline-resistant because of the presence of a tmexCD1-toprJ1-positive plasmid. HD10868 exhibited enhanced fitness and greater tigecycline resistance than HD9932 did. Comparative analysis revealed mutations in the AcrAB-TolC efflux pump and lamb in HD9932 and HD10868. Conclusion: Our study highlights the complexity of resistance gene transfer and underscores the need for continued vigilance and research in this field.