Predictors of mortality in patients with bloodstream infections caused by KPC-producing Klebsiella pneumoniae and impact of appropriate antimicrobial treatment

Abstract

Bloodstream infections (BSIs) caused by Klebsiella pneumoniae carbapenemases (KPC)-producing K. pneumoniae (KPC-KP) are associated with high mortality rates. We investigated outcomes, risk factors for mortality and impact of appropriate antimicrobial treatment in patients with BSIs caused by molecularly confirmed KPC-KP. All consecutive patients with KPC-KP BSIs between May 2008 and May 2010 were included in the study and followed-up until their discharge or death. Potential risk factors for infection mortality were examined by a case-control study. Case-patients were those who died from the BSI and control-patients those who survived. Appropriate antimicrobial therapy was defined as treatment with in vitro active antimicrobials for at least 48 h. A total of 53 patients were identified. Overall mortality was 52.8% and infection mortality was 34%. Appropriate antimicrobial therapy was administered to 35 patients; mortality due to infection occurred in 20%. All 20 patients that received combination schemes had favourable infection outcome; in contrast, seven of 15 patients given appropriate monotherapy died (p 0.001). In univariate analysis, risk factors for mortality were age (p <0.001), APACHE II score at admission and infection onset (p <0.001) and severe sepsis (p <0.001), while appropriate antimicrobial treatment (p 0.003), combinations of active antimicrobials (p 0.001), catheter-related bacteraemia (p 0.04), prior surgery (p 0.014) and other therapeutic interventions (p 0.015) were significantly associated with survival. Independent predictors of mortality were age, APACHE II score at infection onset and inappropriate antimicrobial treatment. Among them, appropriate treatment is the only modifiable independent predictor of infection outcome.