FIG 1.

Mechanisms of ceftolozane/tazobactam (C/T) resistance in 86 carbapenemase-producing CNSPA isolates. a, Bold values indicate ceftazidime/avibactam (CZA) susceptibility. b, The main chromosomal mutations (ampC, ampR, dacB, and ftsI) leading to amino acid substitutions compared to the reference wild-type comparator amino acid sequences from Pseudomonas aeruginosa PAO1 are shown. The list of nonsynonymous variations were refined to include only those more likely to be involved in the C/T-resistant phenotype, i.e., (i) mutations with known effect on resistance according to published evidence and (ii) mutations with predicted functional impact (i.e., deleterious) and not identified in wild-type/susceptible isolates. There were no mutations found in ampR in this set of isolates. PDC, Pseudomonas-derived cephalosporinase; ST, sequence type.