In vitro activity of ceftolozane/tazobactam against Pseudomonas aeruginosa collected in the Study for Monitoring Antimicrobial Resistance Trends (SMART) between 2016-2019 in China.

Abstract

Ceftolozane/tazobactam is an antipseudomonal cephalosporin combined with a well-established β-lactamase inhibitor which has not been approved to datein clinical practice in China. The aim of the study was to evaluate the in vitro activity of ceftolozane/tazobactam and comparator agents against Pseudomonas aeruginosa which demonstrated various resistance patterns. P. aeruginosa (n = 2,178) specimens were collected from multiple sources in seven geographic regions of China from 2016 to 2019. All isolates were identified by MALDI-TOF MS (Bruker Daltonics, MS, USA), and minimum inhibitory concentrations (MICs) of antimicrobial agents including ceftolozane/tazobactam, amikacin, tobramycin, ceftazidime, cefepime, colistin, levofloxacin, aztreonam, meropenem, imipenem, and piperacillin-tazobactam were determined using the CLSI broth microdilution method (BMD). P. aeruginosa demonstrated a considerably higher rate of multidrug-resistant (57.3%), extensive drug-resistant (43.5%) and in being difficult-to-treat (16.8%). The overall susceptibility of P. aeruginosa to ceftolozane/tazobactam was 81.9%, and ceftolozane/tazobactam showed diverse activities against various resistance patterns ranging from 28.5% (difficult-to-treat resistance) to 68.9% (MDR). P. aeruginosa and various resistance patterns derived from the east (Jiangzhe) area maintained a significantly lower susceptibility to ceftolozane/tazobactam than from other areas. The susceptibility rates of P. aeruginosa isolated from diverse sources to ceftolozane/tazobactam were similar to isolates from bloodstream infections (BSI), the highest being88.6%. Compared with comparator antimicrobial agents, ceftolozane/tazobactam was more active than tested β-lactams, while being slightly less active than amikacin, which in turn demonstrated the best activity against P. aeruginosa and multiple resistant subsets. Ceftolozane/tazobactam demonstrated considerable in vitro activity against P. aeruginosa including multiple resistance patterns, indicating that it could be an optional therapeutic agent against P. aeruginosa.