Cefiderocol for the Treatment of Metallo-β-Lactamases Producing Gram-Negative Bacilli: Lights and Shadows From the Literature

Metallo-β-lactamases (MBLs) have recently emerged as one of the most worrisome resistance mechanisms owing to their capacity to hydrolyze all β-lactams, including carbapenems and novel β-lactam/β-lactamase inhibitor combinations, including ceftazidime-avibactam, meropenem-vaborbactam, and imipenem-relebactam [1]. The MBL genes are present in mobile genetic elements such as plasmids, transposons, and integrons and are associated with insertion sequences with a high tendency to spread within and between different species, including both nonfermenters and Enterobacterales isolates. In recent years, the spread of MBL-producing Enterobacterales outside the Indian subcontinent has become alarming and attracted the attention of the worldwide scientific community [2]. A large regional outbreak of New Delhi MBL (NDM)-producing ST147 Enterobacterales occurred in Tuscany, a region of central Italy, and this clone rapidly replaced Klebsiella pneumoniae carbapenemase (KPC)–producing strains that were previously endemic in both nosocomial and community settings [3, 4]. New NDM-9 variants also resistant...