Characterization of the two tandem repeats for the KPC-2 core structures on a plasmid from hospital-derived Klebsiella pneumoniae

Today, Klebsiella pneumoniae strains are sophisticatedly associated with the transmission of KPC, and ST11 clones carrying KPC-2 are an important target for anti-infective clinical therapy, posing a very high threat to patients. To present the detailed genetic features of two KPC-2 core structures of F94_plasmid pA, the whole genome of K. pneumoniae strain F94 was sequenced by nanopore and illumina platform, and mobile genetic elements associated with antibiotic-resistance genes were analyzed with a series of bioinformatics methods. K. pneumoniae strain F94, identified as a class A carbapenemase-resistant Enterobacteriaceae, was resistant to most tested antibiotics, especially to low-levels of ceftazidime/avibactam (avibactam ≤ 4 mg/L), owing to overexpression of the two KPC-2 in F94_plasmid pA. However, strain F94 was sensitive to high-levels of ceftazidime/avibactam (avibactam ≥ 8 mg/L), which correlated with further inhibition of ceftazidime hydrolysis by the KPC-2 enzyme due to the multiplication of avibactam. Collinearity analysis indicated that multi-drug resistance (MDR) regions of plasmids with the tandam repeats of two or more KPC-2 core structures share highly similar structures. This study characterized the MDR region of the F94_ plasmid pA as homologous to plasmids pKPC2_090050, pKPC2_090374, plasmid unnamed 2, pC2414-2-KPC, pKPC2-020037, pBS1014-KPC2, pKPC-J5501, and pKPC2-020002, which contained the tandem repeats of one, two, or more KPC-2 core structures, providing insight into the evolution of multidrug resistance in K. pneumoniae. An alternative theoretical basis for exploring the tandem repeats of two or more KPC-2 core structures was developed by analyzing and constructing the homologous sequence of F94_ plasmid pA.