Klebsiella pneumoniae is a common gut commensal in humans butcan also act as an opportunistic pathogen, causing significant morbidity and mortality worldwide. K. pneumoniae infections are found in both community and hospital settings, and often occur in immunocompromised hosts, such as intensive care patients. These K. pneumoniae infections are accompanied by rising levels of multi-drug resistance, leaving very limited options for antibiotic treatment. Asymptomatic carriage of K. pneumoniae could act as a significant reservoir for infection, yet there is minimal information on K. pneumoniae carriage in hospital patients or in the wider community. A few studies report carriage rates for K. pneumoniae, however most focus on either gut carriage of drug-resistant bacteria, or carriage in the naso/oropharynx.
We investigated the frequency of asymptomatic carriage of K. pneumoniae amongst patients admitted to the intensive care unit (ICU) of an Australian hospital, and the role of such carriage in hospital-acquired K. pneumoniae infections. Rectal and throat swabs were obtained within 3 days of admission to ICU, in most cases, and tested for the presence of K. pneumoniae, revealing average carriage rates of approximately 10%. Carriage rates were higher amongst older patients and those with recent contact with the healthcare system prior to ICU admission. The rate of K. pneumoniae infection was significantly elevated amongst patients with rectal carriage of K. pneumoniae (27% vs 2%, p<1X10-8, OR=17). Paired genome analysis of infection and carriage isolates were mostly consistent with infections being caused by carriage strains (globally-recognised hospital clone CC258 was not detected), with minimal evidence for transmission between patients. Amongst carriers, infection was associated with surgery, antibiotic treatment, and carriage of multi-drug resistant strains.