LAUSR

OBJECTIVES Ceftolozane-tazobactam (C-T) is an antibacterial combination of an antipseudomonal cephalosporin and a β-lactamase inhibitor. C-T was approved in >60 countries for complicated urinary tract infections, acute pyelonephritis, and complicated intra-abdominal infections in combination with metronidazole. Data for Pseudomonas aeruginosa isolates consecutively collected from various infection types in hospitalised patients from 2015-2017 were analysed for this study. METHODS A total of 6836 P. aeruginosa isolates were collected from 104 hospitals on 4 continents and tested for susceptibility (S) to C-T by CLSI broth microdilution methodology at JMI Laboratories using CLSI (2018) breakpoints. Other agents tested were amikacin (AMK), ceftazidime (CAZ), colistin (COL), levofloxacin (LEV), meropenem (MEM), and piperacillin-tazobactam (TZP). Phenotypes analysed included CAZ-non-susceptible (CAZ-NS), COL-NS, MEM-NS, LEV-NS, TZP-NS, and β-lactam-NS (BL-NS). Multidrug resistance (MDR) was identified as NS to ≥1 drug in ≥3 drug classes. Extensively drug-resistant (XDR) was R to ≥1 agent in all but 2 or fewer antimicrobial classes. RESULTS The most common infection from which P. aeruginosa was isolated was pneumonia (51.9%) followed by skin and skin structure (22.0%) and bloodstream (15.3%) infections. The %S for C-T varied by region: 98.2% in North America, 94.8% in Asia-Pacific, 90.8% in Latin America, and 89.1% in Europe. CONCLUSIONS C-T had potent activity against P. aeruginosa isolated from patients in hospitals in 4 continents. C-T was more active than all comparators, except COL, and maintained activity against MDR and XDR isolates and isolates non-susceptible to all 4 tested BLs. C-T was active against 12/16 COL-NS isolates.