Abstract

ObjectivesCystic fibrosis (CF) acute pulmonary exacerbations are often caused by Pseudomonas aeruginosa, including multi-drug resistant strains. Optimal antibiotic therapy is required to return lung function and should be guided by in vitro susceptibility results. There are sparse data describing ETEST performance for CF isolates using contemporary isolates, methods and interpretation, as well as novel antibiotics, such as ceftazidime–avibactam and ceftolozane–tazobactam.MethodsPseudomonas aeruginosa (n = 105) isolated during pulmonary exacerbation from patients with CF were acquired from 3 US hospitals. Minimum inhibitory concentrations (MICs) were assessed by reference broth microdilution (BMD) and ETEST for aztreonam, cefepime, ceftazidime, ceftazidime–avibactam, ceftolozane–tazobactam, ciprofloxacin, levofloxacin, meropenem, piperacillin–tazobactam, and tobramycin. Broth microdilution was conducted in concordance with the Clinical and Laboratory Standards Institute M100. ETEST methodology reflected package insert recommendations. Performance of ETEST strips was evaluated using the Food and Drug Administration (FDA) and Susceptibility Testing Manufacturers Association (STMA) guidance.ResultsOf the 105 P. aeruginosa included, 46% had a mucoid phenotype. ETEST MICs typically read 0–1 dilution higher than BMD for all drugs. Categorical agreement and essential agreement ranged from 64 to 93% and 63 to 86%, respectively. The majority of observed errors were minor. A single very major error occurred with ceftazidime (4.2%). For ceftazidime–vibactam, 2 very major errors were observed and both were within essential agreement. Major errors occurred for aztreonam (3.3%), cefepime (9.4%), ceftazidime–avibactam (5.3%, adjusted 2.1%), ceftolozane–tazobactam (1%), meropenem (3.3%), piperacillin–tazobactam (2.9%), and tobramycin (1.5%).ConclusionsETEST methods performed conservatively for most antibiotics against this challenging collection of P. aeruginosa from patients with CF.

Highlights

  • Cystic fibrosis (CF) is the leading cause of mortality in Caucasians due to autosomal recessive disorders [1]

  • Lasko et al Ann Clin Microbiol Antimicrob (2021) 20:9 median age of survival to over 40 years [1,2,3]. These substantial survival improvements have largely been driven by advancements in prevention and treatment of CF acute pulmonary exacerbation, which is predominately caused by Staphylococcus aureus and Pseudomonas aeruginosa [3,4,5]

  • ~ 20% of CF patients are infected with multi-drug-resistant (MDR) P. aeruginosa, likely due to numerous repetitive antibiotic courses received during treatment of acute pulmonary exacerbations [2,3,4,5]

Read more

Summary

Introduction

Cystic fibrosis (CF) is the leading cause of mortality in Caucasians due to autosomal recessive disorders [1]. Lasko et al Ann Clin Microbiol Antimicrob (2021) 20:9 median age of survival to over 40 years [1,2,3] These substantial survival improvements have largely been driven by advancements in prevention and treatment of CF acute pulmonary exacerbation, which is predominately caused by Staphylococcus aureus (early in the disease) and Pseudomonas aeruginosa (later in the disease) [3,4,5]. Automated antimicrobial susceptibility tests (AST) commonly used in the clinical microbiology lab perform poorly for CF isolates [7]. This study sought to evaluate ETEST performance using current guidance for 10 commonly utilized anti-pseudomonal antibiotics against a contemporary set of P. aeruginosa isolated from CF patients

Objectives
Methods
Results
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call