Extremely drug-resistant NDM-9-producing ST147 Klebsiella pneumoniae causing infections in Italy, May 2020

A large outbreak sustained by New Delhi metallo-beta-lactamase (NDM)-1-producing Klebsiella pneumoniae sequence type (ST) 147 occurred in Tuscany, Italy in 2018–2019. In 2020, NDM-9-producing K. pneumoniae were isolated in the same geographical area. In this study, comparisons at genomic level of these recent isolates with strains representative of the 2018–2019 outbreak were carried out. The 2020 strains were ST147 and had acquired resistance to colistin, tigecycline, and fosfomycin.