Klebsiella pneumoniae species complex bloodstream infection in adult patients: changing epidemiology and determinants of poor outcomes.

Purpose: Klebsiella pneumoniae is a common cause of hospital- and community-acquired infection and can readily acquire multiple antimicrobial resistance determinants leading to poor health outcomes. We define the contemporary burden of disease, risk factors for antimicrobial resistance, and poor health outcomes for patients with K. pneumoniae bloodstream infection (Kp-BSI).

Methods: All blood cultures with growth of K. pneumoniae species complex among residents of Queensland, Australia (population ≈ 5 million) who received care through a public hospital were identified over a 20-year period. Clinical, microbiological and outcome information was obtained from state-wide databases.

Results: A total of 6, 988 patients (7, 496 episodes) with incident Kp-BSI were identified. Incidence rate more than doubled from 5.8 cases to 12.2 cases per 100,000 population over the study period (4.5% rise per year). 258 (3.4%) episodes involved isolates resistant to third-generation cephalosporins (3GC-R). 3GC-R Kp-BSI crude incidence rate increased almost 10% each year. The proportion of hospital-onset episodes reduced from 49.1 to 35.0%. Of all Kp-BSI episodes, 864 (11.5%) died within 30-days. A lower respiratory tract source was associated with a high risk of death (aHR 1.68, 95% CI 1.30-2.16) while a urinary tract source a lower risk (aHR 0.48, 95% CI 0.35-0.66). 3GC-R Kp-BSI was not related to death (aHR 1.08, 95% CI 0.76-1.50).

Conclusion: A rising burden of both Kp-BSI and 3GC-R blood isolates in a previous low-prevalence setting is concerning. A significant rise in community-onset Kp-BSI over the 20-year period was noteworthy and requires further evaluation. 3GC-R status was not associated with mortality.