Gastrointestinal Carriage Is a Major Reservoir of Klebsiella pneumoniae Infection in Intensive Care Patients

Clin Infect Dis. 2017 Jul 15;65(2):208-215. doi: 10.1093/cid/cix270.


Background: Klebsiella pneumoniae is an opportunistic pathogen and leading cause of hospital-associated infections. Intensive care unit (ICU) patients are particularly at risk. Klebsiella pneumoniae is part of the healthy human microbiome, providing a potential reservoir for infection. However, the frequency of gut colonization and its contribution to infections are not well characterized.

Methods: We conducted a 1-year prospective cohort study in which 498 ICU patients were screened for rectal and throat carriage of K. pneumoniae shortly after admission. Klebsiella pneumoniae isolated from screening swabs and clinical diagnostic samples were characterized using whole genome sequencing and combined with epidemiological data to identify likely transmission events.

Results: Klebsiella pneumoniae carriage frequencies were estimated at 6% (95% confidence interval [CI], 3%-8%) among ICU patients admitted direct from the community, and 19% (95% CI, 14%-51%) among those with recent healthcare contact. Gut colonization on admission was significantly associated with subsequent infection (infection risk 16% vs 3%, odds ratio [OR] = 6.9, P < .001), and genome data indicated matching carriage and infection isolates in 80% of isolate pairs. Five likely transmission chains were identified, responsible for 12% of K. pneumoniae infections in ICU. In sum, 49% of K. pneumoniae infections were caused by the patients' own unique strain, and 48% of screened patients with infections were positive for prior colonization.

Conclusions: These data confirm K. pneumoniae colonization is a significant risk factor for infection in ICU, and indicate ~50% of K. pneumoniae infections result from patients' own microbiota. Screening for colonization on admission could limit risk of infection in the colonized patient and others.

Keywords: Klebsiella pneumoniae; gastrointestinal colonization; genomic epidemiology; hospital acquired infection; intensive care.

MeSH terms

  • Adult
  • Aged
  • Anti-Bacterial Agents / pharmacology
  • Carrier State / drug therapy
  • Carrier State / epidemiology*
  • Carrier State / microbiology
  • Cohort Studies
  • Cross Infection / epidemiology
  • Cross Infection / microbiology*
  • Female
  • Gastrointestinal Microbiome*
  • Gastrointestinal Tract / microbiology*
  • Genetic Variation
  • Humans
  • Intensive Care Units*
  • Klebsiella Infections / drug therapy
  • Klebsiella Infections / epidemiology
  • Klebsiella Infections / microbiology*
  • Klebsiella Infections / transmission
  • Klebsiella pneumoniae / drug effects
  • Klebsiella pneumoniae / genetics
  • Klebsiella pneumoniae / isolation & purification*
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Pharynx / microbiology
  • Prospective Studies
  • Rectum / microbiology
  • Risk Factors


  • Anti-Bacterial Agents