Nosocomial outbreak by NDM-1-producing Klebsiella pneumoniae highly resistant to cefiderocol, Florence, Italy, August 2021 to June 2022
Marco Coppi, Alberto Antonelli, Claudia Niccolai, Andrea Bartolini, L. Bartolini, Maddalena Grazzini, Elisabetta Mantengoli, Alberto Farese, Filippo Pieralli, Maria Teresa Mechi, Vincenzo Di Pilato, Tommaso Giani, Gian María Rossolini
Abstract
A nosocomial outbreak by cefiderocol (FDC)-resistant NDM-1-producing Klebsiella pneumoniae (NDM-Kp) occurred in a large tertiary care hospital from August 2021–June 2022 in Florence, Italy, an area where NDM-Kp strains have become endemic. Retrospective analysis of NDM-Kp from cases observed in January 2021–June 2022 revealed that 21/52 were FDC-resistant. The outbreak was mostly sustained by clonal expansion of a mutant with inactivated cirA siderophore receptor gene, which exhibited high-level resistance to FDC (MIC ≥ 32 mg/L) and spread independently of FDC exposure.