Treatment outcome of bacteremia due to KPC-producing Klebsiella pneumoniae: superiority of combination antimicrobial regimens

Abstract

Klebsiella pneumoniae producing Klebsiella pneumoniae carbapenemase (KPC) has been associated with serious infections and high mortality. The optimal antimicrobial therapy for infection due to KPC-producing K. pneumoniae is not well established. We conducted a retrospective cohort study to evaluate the clinical outcome of patients with bacteremia caused by KPC-producing K. pneumoniae. A total of 41 unique patients with blood cultures growing KPC-producing K. pneumoniae were identified at two medical centers in the United States. Most of the infections were hospital acquired (32; 78%), while the rest of the cases were health care associated (9; 22%). The overall 28-day crude mortality rate was 39.0% (16/41). In the multivariate analysis, definitive therapy with a combination regimen was independently associated with survival (odds ratio, 0.07 [95% confidence interval, 0.009 to 0.71], P = 0.02). The 28-day mortality was 13.3% in the combination therapy group compared with 57.8% in the monotherapy group (P = 0.01). The most commonly used combinations were colistin-polymyxin B or tigecycline combined with a carbapenem. The mortality in this group was 12.5% (1/8). Despite in vitro susceptibility, patients who received monotherapy with colistin-polymyxin B or tigecycline had a higher mortality of 66.7% (8/12). The use of combination therapy for definitive therapy appears to be associated with improved survival in bacteremia due to KPC-producing K. pneumoniae.