Carbapenem-Resistant Gram-Negative Bacilli Bacteremia in Argentina (EMBARCAR): Findings From a Prospective, Multicenter Cohort Study

BACKGROUND: Bloodstream infections (BSIs) caused by carbapenem-resistant gram-negative bacilli (CR-GNB) are difficult-to-treat infections associated with high mortality. Outcomes of BSI due to CR-GNB may vary in different countries. METHODS: Prospective observational, multicenter study, including consecutive hospitalized index patients aged ≥18 years, with a positive blood culture for CR-GNB, between July 2020 and March 2022 in Argentina. Among patients with Klebsiella pneumoniae BSIs, logistic regressions adjusted by propensity score (PS) were used to identify variables associated with 30-day mortality. RESULTS: Overall, 466 patients with CR-GNB BSIs were included. The mean age was 56.7 (SD ±16) years and most patients (75%) were in critical care units. The median INCREMENT-CPE mortality score was 10 (IQR, 6-12). Most common micro-organisms were K pneumoniae (53%) and Acinetobacter baumannii (25%). Among Enterobacterales, resistance mechanisms included K pneumoniae carbapenemase (KPC) in 50%, metallo-beta-lactamase carbapenemase (MBL) in 48%, OXA carbapenemase in 6%, and a combination of carbapenemases in 5% of patients. Overall, 30-day mortality was 52%. Among patients with BSI due to K pneumoniae, the PS-adjusted multivariate analysis showed that an INCREMENT-CPE score ≥8 points (odds ratio [OR], 3.48; 95% CI, 1.53, 7.93) was associated with increased 30-day mortality. In contrast, the use of regimens including ceftazidime-avibactam alone or in combination with aztreonam was associated with decreased 30-day mortality (OR, .20; 95% CI, .09, .47). CONCLUSIONS: BSIs due to CR-GNB are associated with high mortality rates in Argentina. Among patients with CR-K pneumoniae bacteremia the use of ceftazidime-avibactam alone or in combination with aztreonam was associated with a reduction in mortality.