A Sequence Type 23 Hypervirulent Klebsiella pneumoniae Strain Presenting Carbapenem Resistance by Acquiring an IncP1 blaKPC-2 Plasmid

Abstract

Hypervirulent Klebsiella pneumoniae strains are typically associated with severe infections and susceptible to most antimicrobial agents. In 2017, a carbapenem-resistant hypervirulent K. pneumoniae (CR-hvKP) strain was isolated from the sputum of a chronic obstructive pulmonary disease (COPD) patient in Zhejiang, China. The goal of the present study was to characterize the molecular features of the CR-hvKP isolate ZJ27003 and its blaKPC-2-harboring plasmid p27003_KPC. Antimicrobial susceptibility was evaluated using the broth microdilution and agar dilution methods. String tests, serum-killing and mouse survival assays were performed to assess virulence, and plasmid conjugation was performed by filter mating. The complete genome sequence of ZJ27003 was acquired using a hybrid assembly of Illumina and Nanopore platform data. The sequence type (ST) of this CR-hvKP isolate was identified as ST23, which exhibits hypervirulence with high serum resistance and murine infection model. The strain is also resistant to carbapenems (imipenem, meropenem and ertapenem), aztreonam and cephalosporins. Additionally, the CR-hvKP isolate carries a 36,708-bp blaKPC-2-harboring plasmid, named p27003_KPC, belonging to the P1 incompatibility (Inc) group. The backbone of p27003_KPC is similar to that of a blaGES-5-harboring Pseudomonas aeruginosa plasmid, in which the blaGES-5 and its surrounding regions were replaced by a blaKPC-2-containing translocatable unit derived from Enterobacteriaceae. The results of a conjugation assay revealed that p27003_KPC can be transferred from K. pneumoniae to P. aeruginosa PAO1 and make the recipient resistant against carbapenem. The identification of a carbapenem-resistant hypervirulent K. pneumoniae isolate carrying and disseminating the blaKPC-2 gene highlights a severe threat to public health.

Emergence of a Hypervirulent Tigecycline-Resistant Klebsiella pneumoniae Strain Co-producing blaNDM–1 and blaKPC–2 With an Uncommon Sequence Type ST464 in Southwestern China

“…The hypermucoviscous phenotype was determined using a string test. A single purified colony on a blood agar plate incubated at 37 • C for 18-24 hours was picked with an inoculation loop for string, and the string test was considered positive if the length of the viscous string was longer than 5 mm (Yan et al, 2021). A serum killing assay was performed as described previously.…”

“…A recent study revealed that, in addition to rmpA, the presence of rmpC and rmpD genes at the rmp locus also contributed to the formation of the hypermucoviscous K. pneumoniae phenotype (Walker et al, 2020). However, not all hypervirulent strains have a mucinous phenotype or carry the rmpA/rmpA2 or iucA genes (Yan et al, 2021). One study indicated that mutations in the genes (wzi, wza, wzc, rcsAB, and lon) that encode the enzymes and regulators responsible for capsule production contributed to aberrant capsule production that promoted the pathogenicity and antiserum phagocytosis of K. pneumoniae strains.…”

Metagenomic Approaches Reveal Strain Profiling and Genotyping of Klebsiella pneumoniae from Hospitalized Patients in China

“…Besides, the MDR hypervirulent ST23 K. pneumoniae , whose rapid dissemination is driven by diverse plasmids harboring virulence and ARM genes, is another clinically significant lineage that has been paid close attention to by the medical community ( 13 , 36 – 38 ). Meanwhile, the highest numbers of virulence genes were observed in the two ST23 strains (Kpn15 and Kpn16) carrying KL1, a well-characterized capsule type highly associated with hvKP strains ( 39 ).…”

Outer Membrane Vesicles Transmitting bla NDM-1 Mediate the Emergence of Carbapenem-Resistant Hypervirulent Klebsiella pneumoniae

“…The generation of K. pneumoniae strains that are hypervirulent (hv) and carbapenem resistant poses a serious threat to public health ( 3 ) and has three different evolutionary paths: hvKP strains may acquire drug-resistant plasmids, forming carbapenem-resistant hypervirulent K. pneumoniae (CR-hvKP) ( 4 – 7 ); CRKP strains may acquire virulence plasmids, forming hv-CRKP ( 8 ); and virulence and carbapenem resistance genetic elements may integrate into a single plasmid ( 9 ). In hvKP, horizontal gene transfer (HGT) is constrained by the substantially thickened polysaccharide capsule and the limited chromosomal recombination; the reduced plasmid diversity results in a reduction in pangenomic diversity ( 10 ).…”