Emergence of a hypervirulent carbapenem-resistant Klebsiella pneumoniae isolate from clinical infections in China

J Infect. 2015 Nov;71(5):553-60. doi: 10.1016/j.jinf.2015.07.010. Epub 2015 Aug 21.

Abstract

Objectives: Hypervirulent Klebsiella pneumoniae (hvKP) infections occur worldwide, but carbapenem-resistant hvKP strain has rarely been observed.

Methods: A retrospective study was conducted in 28 cases of carbapenem-resistant K. pneumoniae (CRKP) infections from 9 cities in China. Clinical data were collected from medical records. All the isolates were characterized by antimicrobial susceptibility testing, string test, multilocus sequence typing, and capsular genotyping. All the hypermucoviscous CRKP strains were analyzed by virulence gene profiles, serum killing assay, and mouse lethality assay.

Results: Of 28 CRKP isolates, five were positive for string test. Importantly, one of the hypermucoviscous strains isolated from blood sample was identified as hvKP. The hypervirulent CRKP strain showed highly resistant to carbapenems (MIC > 32 μg/mL), decreased expression of ompK35/36, and ESBLs production. Significantly increased resistance to serum killing and mice mortality were found in the hypervirulent CRKP strain compared to the other CRKPs. Capsular polysaccharide synthesis genotyping revealed that the hypervirulent strain belongs to K2 serotype, while others belong to K-nontypable serotype. The K2 hypervirulent CRKP strain carried rmpA, aerobactin, entB, and mrkD genes.

Conclusions: The newly emerged hypervirulent carbapenem-resistant K. pneumoniae might cause a serious threat to public health, suggesting an urgent need to enhance clinical awareness and epidemiologic surveillance.

Keywords: Carbapenem-resistance; Clinical features; Hypervirulent K. pneumoniae; Molecular characteristics; Virulence.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Aged
  • Aged, 80 and over
  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Carbapenems / pharmacology*
  • China / epidemiology
  • Drug Resistance, Multiple, Bacterial / genetics
  • Female
  • Genotype
  • Humans
  • Infant, Newborn
  • Klebsiella Infections / epidemiology
  • Klebsiella Infections / microbiology*
  • Klebsiella Infections / mortality
  • Klebsiella pneumoniae / drug effects
  • Klebsiella pneumoniae / genetics
  • Klebsiella pneumoniae / isolation & purification*
  • Klebsiella pneumoniae / pathogenicity*
  • Lethal Dose 50
  • Male
  • Medical Records
  • Mice
  • Multilocus Sequence Typing
  • Retrospective Studies
  • Serogroup
  • Virulence / genetics

Substances

  • Anti-Bacterial Agents
  • Carbapenems