Association of Carbapenemase Gene Profiles with Ceftazidime–avibactam Resistance in Carbapenem-Resistant Klebsiella pneumoniae

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a major healthcare threat, and carbapenemase genotype may influence ceftazidime–avibactam (CZA) susceptibility. This study evaluated the association between carbapenemase gene profiles and CZA resistance in CRKP isolates. In this retrospective laboratory-based study, 184 CRKP isolates (92 CZA-susceptible and 92 CZA-resistant) were analyzed. Carbapenemase genes were detected by multiplex real-time PCR, and gene distributions and profiles were compared according to CZA susceptibility. NDM was detected in 82.6% of CZA-resistant isolates but in none of the susceptible isolates (q < 0.001). All CZA-susceptible isolates carried a single carbapenemase gene, whereas 68.5% of resistant isolates carried two or more genes. NDM + OXA-48-like was the predominant profile among resistant isolates (63.0%), while OXA-48-like alone predominated among susceptible isolates (92.4%) (both q < 0.001). NDM showed 82.6% sensitivity and 100% specificity for discriminating CZA resistance, with an AUC of 0.913. Amikacin resistance was also higher among CZA-resistant isolates (60.9% vs. 31.5%; q < 0.001). NDM, particularly when co-occurring with OXA-48-like, was strongly associated with CZA resistance. Rapid carbapenemase genotyping may complement phenotypic susceptibility testing and support antimicrobial treatment decisions.