synergistic activity of aztreonam (AZT) plus novel and old β-lactamase inhibitor combinations against metallo-β-lactamase-producing AZT-resistant .

The emergence of metallo-β-lactamase (MBL)-producing , mainly New Delhi metallo-β-lactamase (NDM), represents a clinical threat due to the limited therapeutic alternatives. Aztreonam (AZT) is stable to MBLs, but most MBL-producing isolates usually co-harbour other β-lactamases that confer resistance to AZT and, consequently, its use is restricted in these isolates. We compared the ability of sulbactam (SUL), tazobactam (TAZ), clavulanic acid (CLA) and avibactam (AVI) to restore the AZT activity in MBL-producing AZT-resistant isolates.