Carbapenem resistance among Klebsiella pneumoniae isolates: risk factors, molecular characteristics, and susceptibility patterns

Infect Control Hosp Epidemiol. 2009 Jul;30(7):666-71. doi: 10.1086/598244.


Background: Carbapenem resistance among isolates of Klebsiella pneumoniae has been unusual.

Objectives: To identify risk factors for infection with carbapenem-resistant K. pneumoniae (CRKP) and to characterize microbiological aspects of isolates associated with these infections.

Design: Retrospective case-control study.

Setting: A 900-bed tertiary care hospital.

Results: From January 2006 through April 2007, K. pneumoniae was isolated from 461 inpatients; 88 had CRKP infection (case patients), whereas 373 had carbapenem-susceptible K. pneumoniae infection (control subjects). The independent risk factors for infection with CRKP were prior fluoroquinolone use (odds ratio [OR], 1.87 [95% confidence interval [CI], 1.07-3.26]; P=.026), previous receipt of a carbapenem drug (OR, 1.83 [95% CI, 1.02-3.27]; P=.042), admission to the intensive care unit (OR, 4.27 [95% CI, 2.49-7.31]; P<.001), and exposure to at least 1 antibiotic drug before isolation of K. pneumoniae (OR, 3.93 [95% CI, 1.15-13.47]; P=.029). All CRKP isolates carried the bla(KPC) gene. Approximately 90% of the tested isolates carried the bla(KPC-2) allele, suggesting patient-to-patient transmission. Almost all CRKP isolates were resistant to all antibiotics, except to colistin (resistance rate, 4.5%), gentamicin (resistance rate, 7%), and tigecycline (resistance rate, 15%).

Conclusions: CRKP should be regarded as an emerging clinical threat. Because these isolates are resistant to virtually all commonly used antibiotics, control of their spread is crucial.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / pharmacology*
  • Carbapenems / pharmacology*
  • Cross Infection / microbiology
  • Cross Infection / transmission
  • Drug Resistance, Bacterial / genetics*
  • Female
  • Humans
  • Israel / epidemiology
  • Klebsiella Infections / microbiology
  • Klebsiella Infections / transmission
  • Klebsiella pneumoniae / drug effects*
  • Klebsiella pneumoniae / enzymology
  • Klebsiella pneumoniae / genetics
  • Klebsiella pneumoniae / isolation & purification
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Prevalence
  • Risk Factors
  • beta-Lactamases / genetics


  • Anti-Bacterial Agents
  • Carbapenems
  • beta-lactamase KPC-2
  • beta-Lactamases