Ceftazidime–Avibactam in Multidrug-Resistant Klebsiella spp. Infections: Is Monotherapy as Effective as Combination Therapy?

Background/Objectives: Carbapenem-resistant Klebsiella spp. (CRK) causes healthcare-associated infections with high mortality. This study evaluated the clinical outcomes of ceftazidime–avibactam (CZA) therapy in CRK infections. Methods: Patients hospitalized in a tertiary care hospital in Türkiye between June 2021 and December 2022 with CRK-positive cultures, CZA susceptibility, and ≥72 h of CZA treatment were retrospectively analyzed. Results: Ninety-nine patients (61.6% male; mean age 63.7 ± 17.5 years) were included, 89.9% of whom were treated in the intensive care unit (ICU). Hypertension (29.3%), diabetes (28.3%), and malignancy (26.3%) were the most frequent comorbidities. The main infection types were bloodstream infection (56.6%) and ventilator-associated pneumonia (29.3%). CZA was used as monotherapy in 49.5%, and in combination in 50.5% of cases. The mean treatment duration was 13.2 ± 6.3 days. Clinical improvement occurred at 3.4 ± 1.2 days and microbiological eradication at 4.7 ± 2.1 days. Treatment success was achieved in 76.8% of patients, while 30- and 90-day mortality rates were 48.5% and 72.7%, respectively. Only treatment duration significantly affected clinical outcome (p < 0.001). Conclusions: CZA demonstrates favorable outcomes in CRK infections, with no significant difference between monotherapy and combination therapy. These findings support the use of CZA as an effective treatment option for severe CRK infections in real-world clinical settings and may help guide antimicrobial stewardship strategies in high-risk hospitalized patients.