Comparison of Effectiveness between Ceftazidime/Avibactam and Other Active Therapies for Oxacillinase-48-Producing Carbapenem-Resistant Klebsiella pneumoniae Bacteremia in Taiwan.

Introduction: Oxacillinase-48 (OXA-48)-producing carbapenem-resistant Klebsiella pneumoniae (CRKP) infections have been increasingly reported in Taiwan. Real-world studies regarding effective treatments for these infections are limited, and recommendations from international guidelines are controversial. The aim of this study was to compare clinical outcomes of OXA-48-producing CRKP bacteremia between patients treated with ceftazidime/avibactam (CZA) and those receiving other active therapies.

Methods: Unique adult patients with OXA-48-producing CRKP bacteremia who received CZA or other therapies in vitro for at least 3 days between June 2017 and December 2024 at Taipei Veterans General Hospital were enrolled. Clinical characteristics and outcomes were compared among the treatment groups. OXA-48 strains were detected using polymerase chain reaction (PCR) followed by Sanger sequencing.

Results: Of 45 patients included in this study, 18 were treated with CZA, and 27 were treated with other active therapies. Four patients received combination therapy. Most strains were OXA-48 producers (n = 42), and the rest were OXA-181 producers. No significant difference in 30-day mortality rate was observed between the treatment groups (22.2% versus 33.3%, p = 0.420), and even in critically ill patients (28.6% versus 43.8%, p = 0.389). Acute Physiology and Chronic Health Evaluation II (APACHE II) score (hazard ratio [HR] 1.07, 95% confidence interval [CI] 1.01-1.15, p = 0.028) was an independent risk factor for 30-day mortality, and colistin-based therapy (HR 3.02, 95% CI 1.00-9.13, p = 0.050) showed marginal significance with 30-day mortality. CZA use was not associated with 30-day mortality.

Conclusions: Our findings revealed that CZA and other active therapies showed similar outcomes, but colistin-based regimens should be used cautiously.