Sequential Treatment Failure With Aztreonam-Ceftazidime-Avibactam Followed by Cefiderocol Due to Preexisting and Acquired Mechanisms in a New Delhi Metallo-β-lactamase–Producing <i>Escherichia coli</i> Causing Fatal Bloodstream Infection

Abstract

We report a fatal case of New Delhi metallo-β-lactamase (NDM)-producing Escherichia coli in a bacteremic patient with sequential failure of aztreonam plus ceftazidime-avibactam followed by cefiderocol. Acquired resistance was documented phenotypically and mediated through preexisting and acquired mutations. This case highlights the need to rethink optimal treatment for NDM-producing organisms.