Bloodstream infections caused by metallo-β-lactamase/Klebsiella pneumoniae carbapenemase-producing K. pneumoniae among intensive care unit patients in Greece: risk factors for infection and impact of type of resistance on outcomes

Abstract

Objective: To determine risk factors for bloodstream infections (BSIs) caused by Klebsiella pneumoniae producing metallo-β-lactamases (MBLs) or K. pneumoniae carbapenemases (KPCs), as well as risk factors for mortality associated with carbapenem-resistant K. pneumoniae, among intensive care unit (ICU) patients.

Methods: Two case-control studies were conducted in a patient cohort with K. pneumoniae BSIs in an 8-bed ICU in a Greek hospital from January 1, 2007, through December 31, 2008. In study 1, patients with K. pneumoniae BSIs were allocated among 3 groups according to isolate susceptibility profile: (1) carbapenem-susceptible insolates (control group), (2) MBL-producing isolates, or (3) KPC-producing isolates. The MBL and KPC groups were compared with the control group to identify risk factors for development of K. pneumoniae BSI. In study 2, patients with K. pneumoniae BSIs who died were compared with survivors to identify risk factors for mortality.

Results: Fifty-nine patients had K. pneumoniae BSIs (22 with carbapenem-susceptible isolates, 18 with MBL-producing isolates, and 19 with KPC-producing isolates). All KPC-producing isolates carried the bla(KPC-2) gene, and 17 of 18 MBL-producing isolates carried bla(VIM-1). Acute Physiology and Chronic Health Evaluation II score (odds ratio, 1.13 [95% confidence interval, 1.03-1.25]; [Formula: see text]) was independently associated with KPC-producing K. pneumoniae BSIs. Nine (41%) of 22 control patients, 8 (44%) of 18 MBL group patients, and 13 (68%) of 19 KPC group patients died in the ICU. Nine (41%) of 22 control patients, 10 (56%) of 18 MBL group patients, and 15 (79%) of 19 KPC group patients died in the hospital. Isolation of KPC-producing K. pneumoniae was an independent predictor of ICU death ([Formula: see text]) and in-hospital death ([Formula: see text]) but not infection-attributable death.

Conclusions: BSIs due to KPC-producing K. pneumoniae resulted in significantly increased mortality. The accurate and rapid detection of these pathogens is necessary for therapeutic considerations and for the implementation of infection control measures to contain them.