Genomic characterisation of a multidrug-resistant Klebsiella pneumoniae co-harbouring bla, bla, and tet(A) isolated from the bloodstream infections of patients.

Objectives: Carbapenem-resistant Klebsiella pneumoniae (CRKP), a superbug that can be difficult or impossible to treat, has become a worldwide problem. This study presents the first report of a CRKP strain carrying a plasmid co-harbouring bla, bla, and tet(A) and the subsequent analysis of its genomic features.

Methods: Isolation and identification of bacteria, antimicrobial susceptibility test, whole genome sequencing, and conjugation experiments assay were conducted in clinical epidemiological investigations and plasmid genetic characterisation analysis.

Results: A total of 116 strains of bacteria were isolated from patients with bloodstream infections (BSI) between 2018 and 2023. A total of 89.66% of the isolates were carbapenem-resistant Enterobacteriaceae (CRE), with the majority (75/116) being CRKP. Among these, a novel plasmid co-harbouring bla, bla, and tet(A) simultaneously was found in CRKP46, and the three genes mediated conjugation by IS26, ISAba125, and IS26, respectively. This plasmid conferred carbapenem resistance to E. coli J53 after conjugative transfer, which was 2 times greater than that of CRKP46.

Conclusion: The present study identified the occurrence of a rare plasmid co-harbouring bla, bla, and tet(A), and the spread of these genes was mediated by the corresponding mobile elements. The increased carbapenem resistance created by this novel plasmid challenges public health security and poses a potential threat to human health; therefore, it deserves attention.