Ceftolozane-tazobactam and ceftazidime-avibactam activity against β-lactam-resistant Pseudomonas aeruginosa and extended-spectrum β-lactamase-producing Enterobacterales clinical isolates from U.S. medical centres

J Glob Antimicrob Resist. 2020 Sep:22:689-694. doi: 10.1016/j.jgar.2020.04.017. Epub 2020 Apr 27.

Abstract

Background: Despite availability of ceftolozane-tazobactam (C/T) and ceftazidime-avibactam (CZA) for several years, the individual spectrum of activity of each agent may not be widely known. We compared the activity of C/T and CZA against convenience samples of 119 extended-spectrum β-lactamase (ESBL)-producing Enterobacterales and 60 β-lactam-resistant Pseudomonas aeruginosa clinical isolates collected from three U.S. institutions.

Methods: Minimal inhibitory concentrations (MICs) for C/T and CZA were determined by broth microdilution. Molecular identification of nine β-lactamase gene targets was conducted for Enterobacterales and P. aeruginosa isolates with increased MICs to C/T or CZA.

Results: More than 90% of Enterobacterales isolates demonstrated susceptibility to both C/T and CZA, in contrast to the other traditional β-lactam agents tested, which were much less active. The MIC50/90 values were nearly equivalent between agents. The most common β-lactamase genes identified in Enterobacterales isolates with MIC values ≥2 mg/L were the CTX-M-1 group (85%) and CMY-2-like (23%) β-lactamases. Both agents were active against >80% of β-lactam-resistant P. aeruginosa isolates tested, most of which had oprD mutations identified. One P. aeruginosa isolate was positive for a Klebsiella pneumoniae carbapenemase-type gene but remained meropenem-susceptible. The MIC50 values were four-fold lower in favour of C/T (1 mg/L vs. 4 mg/L) against P. aeruginosa.

Conclusions: Our data suggest that either agent may be a reasonable choice for centres with a high proportion of ESBL producers; however, C/T may have improved activity against P. aeruginosa and may be preferred in institutions with a higher frequency of resistant pseudomonal isolates.

Keywords: ESBL; MDR; Multidrug-resistant; beta-lactamase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use
  • Azabicyclo Compounds
  • Ceftazidime
  • Cephalosporins
  • Drug Combinations
  • Humans
  • Pseudomonas Infections* / drug therapy
  • Pseudomonas aeruginosa* / genetics
  • Tazobactam / pharmacology
  • beta-Lactamases / genetics

Substances

  • Anti-Bacterial Agents
  • Azabicyclo Compounds
  • Cephalosporins
  • Drug Combinations
  • avibactam, ceftazidime drug combination
  • ceftolozane
  • Ceftazidime
  • beta-Lactamases
  • Tazobactam