Comparison of outcomes of KPC-producing Enterobacterales bloodstream infections treated with ceftazidime-avibactam and other conventional antibiotics: retrospective single-center study

Ceftazidime-avibactam (CZA) was introduced in South Korea in July 2023, but regional data on its clinical efficacy, treatment outcomes, and microbiological characteristics of bloodstream infections (BSIs) caused by <i>Klebsiella pneumoniae</i> carbapenemase (KPC)-producing Enterobacterales remain limited. This study evaluated the effectiveness of CZA compared with conventional therapies targeting KPC-producing Enterobacterales BSIs. A retrospective observational study of adult patients with KPC-producing Enterobacterales BSIs was conducted at a tertiary care center in Seoul, Republic of Korea. Patients treated with CZA between July 2023 and November 2024 were compared with a historical cohort treated with best available agents (conventional therapy) from December 2021 to June 2023. The primary endpoint was 30-day all-cause mortality. Secondary endpoints included BSI persistence, BSI recurrence, and emergence of resistance. A total of 106 patients received CZA and 156 received best available agents. The 30-day mortality rate was significantly lower in the CZA group compared with the comparator group (15.1% vs 28.2%, <i>P</i> = 0.02). Persistent BSI was also significantly reduced in the CZA group (5.0% vs 34.2%, <i>P</i> < 0.001). In multivariate analysis, CZA therapy was independently associated with reduced 30-day mortality (adjusted OR, 0.46; 95% CI, 0.22-0.92). Kaplan-Meier analysis demonstrated improved survival with CZA (<i>P</i> = 0.014), and CZA resistance emerged in three patients (2.8%, 3/106). In this Korean cohort, CZA therapy was associated with significantly lower 30-day mortality and persistent BSI rates in patients with KPC-producing Enterobacterales BSIs, compared with best available agents.IMPORTANCEBloodstream infections caused by <i>Klebsiella pneumoniae</i> carbapenemase (KPC)-producing Enterobacterales carry high mortality rates and offer few treatment options, representing an urgent public health threat. Ceftazidime-avibactam (CZA) has emerged as a key therapy for these infections globally, yet real-world clinical data from South Korea have been absent since its recent introduction. This study presents the first comprehensive evaluation of CZA for treating KPC-producing Enterobacterales bloodstream infections in a Korean tertiary-care hospital. Through direct comparison with conventional combination regimens, we show that CZA substantially reduces 30-day mortality and persistent bacteremia. These findings provide important evidence for CZA as an effective first-line treatment, especially in settings where KPC-producing organisms are highly prevalent. Our results emphasize the value of timely access to novel β-lactam/β-lactamase inhibitors and point to the ongoing need for resistance surveillance.