The recent discovery of carbapenemase-producing hypervirulent Klebsiella pneumoniae (CP-HvKP) has signaled the convergence of multidrug resistance and pathogenicity, with the potential for increased mortality. While previous studies of CP-HvKP isolates revealed that most carried carbapenemase genes and hypervirulence elements on separate plasmids, a 2018 report from China confirmed that both could be harbored on a single, hybrid carbapenemase-hypervirulent plasmid. As part of a project sequencing isolates carrying multiple carbapenemase genes identified through CDC’s Antibiotic Resistance Laboratory Network (AR Lab Network), we discovered a bla_NDM-1-bearing hypervirulent plasmid found in a KPC- and NDM-positive K. pneumoniae from the United States.

Antimicrobial susceptibility testing (AST) was performed by reference broth microdilution against 23 agents. Whole-genome sequencing (WGS) was performed on Illumina MiSeq and PacBio RS II platforms.

AST results indicated the isolate was extensively drug-resistant, as it was non-susceptible to at least one agent in all but two drug classes; it was susceptible to only tigecycline and tetracycline. Analysis of WGS data showed the isolate was ST11, the same sequence type that caused a fatal outbreak of CP-HvKP in China in 2016. The genome included two plasmids. The smaller one (129kbp) carried seven antibiotic resistance (AR) genes, including the carbapenemase gene bla_KPC-2. The larger plasmid (354kbp) harbored 11 AR genes, including the metallo-β-lactamase gene bla_NDM-1, as well as virulence factors iucABCD/iutA, peg-344, rmpA, and rmpA2, which comprise four of the five genes previously identified as predictors of hypervirulence in K. pneumoniae.

This is the first report of a hybrid carbapenemase-hypervirulent plasmid in the United States. The presence of both blaNDM-1 and hypervirulence elements on the same plasmid suggests that the CP-Hv pathotype could spread rapidly through horizontal transfer. This discovery demonstrates the critical role of genomic characterization of emerging resistance and virulence phenotypes by the AR Lab Network as part of US containment efforts.

All authors: No reported disclosures.