Characteristics of multidrug-resistant hypervirulent Klebsiella pneumoniae strains ST29 and K212 harbouring tmexC2-tmexD2-toprJ2.

OBJECTIVES

This study aimed to characterize a tigecycline-resistant hypervirulent Klebsiella pneumoniae (HvKP) strain, identified as KLZT, which carries the tigecycline resistance gene cluster tmexC2-tmexD2-toprJ2 belonging to ST29 and serotype K212.

METHODS

Antimicrobial susceptibility and virulence phenotypes were assessed, followed by whole-genome sequencing (WGS) using PacBio II and MiSeq sequencers. Genome annotation was carried out using the RAST server and bioinformatics analysis revealed the genetic characteristics of this strain.

RESULTS

Antimicrobial and virulence phenotype testing indicated that K. pneumoniae strain KLZT could be considered as a multidrug-resistant HvKP. WGS analysis showed that KLZT has a single 5,536,506-bp chromosome containing three plasmids 290,963 bp (pKLZT-1), 199,302 bp (pKLZT-2), and 4820 bp (pKLZT-3) in size, and also includes the ST29 and K212 serotypes. Four (bla, oqxA, oqxB, and fosA6) and six resistance genes (tmexC2-tmxeD2-toprJ2, bla, aac(6')-Ib-cr, catB3, arr-3, and bla) were identified from chromosomal and plasmid pKLZT-1, respectively. Gene-based analysis of the resistance genes of plasmid pKLZT-1 showed that the tigecycline resistance gene cluster-carrying region was flanked by umuC and umuD (umuD-hps-IS5-tmexC2-tmexD2-toprJ2-umuC), as well as other resistance genes and virulence factors (ureB, ureC, and ureG), which were carried by IS5075-Tn3-intI1 -aac(6')-Ib-cr-bla-catB3-arr-3-bla-Tn3-ISkpn26-ureBCG-IS5075.

CONCLUSIONS

WGS has revealed that a multidrug-resistant strain, HvKP KLZT, belonging to ST29 with capsular serotype K212, contains a multidrug-resistance plasmid.