- September 23, 2026
Combating Carbapenem-Resistant Enterobacterales: Comparative In Vitro Efficacy of Aztreonam–Avibactam and Ceftazidime–Avibactam and Distribution of Carbapenemase Genes
Melike Yaşar Duman, Mervenur Kanat, Elif Seren Tanrıverdi, Feriha Çilli and Şöhret Aydemir | Department of Medical Microbiology, Faculty of Medicine, Ege University, 35100 Izmir, Türkiye; Department of Medical Microbiology, Faculty of Medicine, ˙Inönü University, 44280 Malatya, Türkiye | 2026 | 10.3390/antibiotics15080724
Carbapenem-resistant Enterobacterales (CRE), which includes strains such as Escherichia coli and Klebsiella pneumoniae, are bacteria that have developed resistance to carbapenem antibiotics, making infections such as urinary tract and bloodstream infections increasingly difficult to treat. This resistance is often linked to carbapenemase enzymes, which break down carbapenem antibiotics and reduce their effectiveness against bacterial infections. In this study, researchers evaluated the in vitro activity of aztreonam-avibactam and ceftazidime-avibactam against 100 invasive CRE isolates collected from blood cultures and other sterile body fluids. Species identification and antimicrobial susceptibility testing were performed to characterise the isolates and assess the effectiveness of aztreonam-avibactam and ceftazidime-avibactam against the bacteria. Carbapenemase-encoding genes associated with antibiotic resistance were subsequently detected using real-time Polymerase Chain Reaction (PCR) on the Magnetic Induction Cycler (Mic IVD). Molecular analysis revealed a high prevalence of the carbapenemase genes blaNDM and blaOXA-48, with blaNDM strongly associated with resistance to ceftazidime-avibactam. The study found that aztreonam-avibactam demonstrated substantially greater in vitro activity than ceftazidime-avibactam, with 98% of isolates being effectively inhibited compared with 31% for ceftazidime-avibactam. These findings highlight the importance of molecular surveillance in monitoring emerging antimicrobial resistance patterns and suggest that aztreonam-avibactam may be an effective treatment option for CRE infections in regions with emerging metallo-β-lactamase prevalence.