“…Wild-type E. coli CFT073-RR, an already sequenced reference clinical uropathogenic strain, and its transconjugant E. coli CFT073-RR Tc bla CTX-M-15 , harbouring a plasmid carrying bla CTX-M-15 , bla OXA-1 and aac(6ʹ)-1b, obtained by conjugation of CFT073-RR with a clinical isolate of community-acquired urinary tract infection [8,9], were used. The MICs of ceftolozane, tazobactam, ceftolozane/tazobactam (with a fixed tazobactam concentration of 4 mg/ L according to the reference method, and with a 2:1 ratio as in the manufactured formulation for therapeutic use) and imipenem, were determined in triplicate by microdilution at standard or high inoculum (10 5 and 10 7 CFU/mL, respectively).…”