Susceptibility of multidrug resistant Pseudomonas aeruginosa to ceftolozane-tazobactam and comparison of different susceptibility testing methods

The objectives of this study were to investigate the ceftolozane-tazobactam (C/T) resistance rates of multidrug-resistant (MDR) and extensively drug resistant (XDR) P. aeruginosa from a German tertiary care hospital. Further aims were to study the underlying resistance genes, the clonal structure and different antimicrobial susceptibility testing (AST) methods regarding their accuracy for C/T testing. A randomly selected subset of 77 isolates was subjected to whole genome sequencing to assess the clonal structure of this collection.