Comparative Outcomes of Bloodstream Infections Caused by KPC- and NDM-Producing Gram-Negative Pathogens

Background: Bloodstream infections (BSI) due to carbapenem-resistant gram-negative bacilli (CR-GNB), especially Klebsiella pneumoniae carbapenemase (KPC) and New-Delhi metallo-β-lactamase (NDM) producers, are associated with high morbidity and mortality. We aimed to compare the outcomes, specifically 30-day and overall in-hospital crude mortality, among patients with BSIs from KPC-producing or NDM-producing GR-GNB, in a tertiary-care, Greek hospital. Materials and Methods: We conducted a single-center, retrospective, observational study from January 1 to December 31, 2023. All consecutive adult patients with confirmed BSI due to KPC-producing or NDM-producing CR-GNB during the period were included in the study. The primary outcome was the 30-day in-hospital crude mortality rate. Results: We recorded 133 episodes of BSIs in 118 unique patients; 79 episodes were due to KPC-producing and 54 to NDM-producing CR-GNB (incidence 0.49 and 0.31 episodes per 1000 patient-days, respectively). We found high 30-day crude mortality rates for patients with BSIs due to KPC-producing CR-GNB (26.4%) and NDM-producing CR-GNB (37%). Bacteremias due to NDM-producing Pseudomonas aeruginosa had the highest 30-day (47.1%) and overall (70.6%) in-hospital, crude mortality. Treatment with beta-lactam/beta-lactamase inhibitors as monotherapy or in combination with other active agents (ie, colistin and/or tigecycline) was associated with improved survival rates among patients with KPC-producing GNB ( P =0.009). Conclusions: In conclusion, we found a high incidence of BSIs due to NDM-producing and KPC-producing CR-GNB, associated with high in-hospital mortality, especially among patients with NDM-producing P. aeruginosa .