Longitudinal Surveillance and Combination Antimicrobial Susceptibility Testing of Multidrug-Resistant Achromobacter Species from Cystic Fibrosis Patients

Ijeoma Okoliegbe* (Corresponding Author), Karolin Hijazi, Kim Cooper, Corinne Ironside, Ian M Gould

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Achromobacter spp. are recognized as emerging pathogens in patients with cystic fibrosis (CF). Though recent works have established species-level identification using nrdA sequencing, there is a dearth in knowledge relating to species-level antimicrobial susceptibility patterns and antimicrobial combinations, which hampers the use of optimal antimicrobial combinations for the treatment of chronic infections. The aims of this study were to (i) identify at species-level referred Achromobacter isolates, (ii) describe species-level antimicrobial susceptibility profiles, and (iii) determine the most promising antimicrobial combination for chronic Achromobacter infections. A total of 112 multidrug-resistant (MDR) Achromobacter species isolates from 39 patients were identified using nrdA sequencing. Antimicrobial susceptibility and combination testing were carried out using the Etest method. We detected six species of Achromobacter and found that Achromobacter xylosoxidans was the most prevalent species. Interestingly, sequence analysis showed it was responsible for persistent infection (18/28 patients), followed by Achromobacter ruhlandii (2/3 patients). Piperacillin-tazobactam (70.27%) and co-trimoxazole (69.72%) were the most active antimicrobials. Differences were observed in species-level susceptibility to ceftazidime, carbapenems, ticarcillin-clavulanate, and tetracycline. Antimicrobial combinations with co-trimoxazole or tobramycin demonstrate the best synergy, while co-trimoxazole gave the best susceptibility breakpoint index values. This study enriches the understanding of MDR Achromobacter spp. epidemiology and confirms prevalence and chronic colonization of A. xylosoxidans in CF lungs. It presents in vitro data to support the efficacy of new combinations for use in the treatment of chronic Achromobacter infections.

Original languageEnglish
Article numbere01467
Number of pages10
JournalAntimicrobial Agents and Chemotherapy
Volume64
Issue number11
Early online date20 Oct 2020
DOIs
Publication statusPublished - Nov 2020

Keywords

  • Achromobacter spp
  • A. xylosoxidans
  • Cystic Fibrosis
  • Antimicrobial susceptibility testing
  • Synergy testing
  • Etest
  • antimicrobial susceptibility testing
  • cystic fibrosis
  • synergy testing
  • Achromobacter spp.
  • AMINOGLYCOSIDE RESISTANCE
  • XYLOSOXIDANS
  • PREVALENCE
  • OUTCOMES
  • Cystic fibrosis

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