A seemingly considerable increase in antimicrobial resistance in the Bacteroides fragilis group from blood cultures: the second national study in Denmark

Maiken Florisson*, Ziyap Acar, Barbara Juliane Holzknecht, Claus Østergaard, Dennis Back Holmgaard, Esad Dzajic, Jurgita Samulioniené, Kristian Schønning, Lillian Marie Søes, Mikala Wang, Turid Snekloth Søndergaard, Ulrik Stenz Justesen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Background: Bacteroides fragilis group species are the most frequently encountered bacteria involved in anaerobic bacteraemia and associated with high mortality rates. In 2012, we performed the first national study of antimicrobial susceptibility in the B. fragilis group from blood cultures in Denmark. Objectives: The purpose of the present study was to compare the antimicrobial susceptibility rates of piperacillin-tazobactam, meropenem, clindamycin and metronidazole in the B. fragilis group from blood cultures in Denmark in 2022 with susceptibility rates from 2012. In addition, we wanted to investigate whether changes to susceptibility was related to the overall use of the specified antimicrobial agents from 2012 to 2022. Methods: Antimicrobial susceptibility testing was performed in accordance with EUCAST guidelines using the agar dilution method and the disc diffusion method. Results: The study showed a seemingly considerable increase in resistance in the B. fragilis group (n = 234) to piperacillin-tazobactam from a reported 8.5% in 2012 to 42.7% in 2022. Resistance towards meropenem also increased from a reported 3.4% to 10.7%. Most of the increase in resistance for piperacillin-tazobactam and meropenem is caused by a recent EUCAST breakpoint change. Metronidazole still has the lowest resistance rate for the B. fragilis group (one isolate, 0.4%) in this study. The sales of piperacillin-tazobactam in the same period revealed a corresponding increase (+130%), whereas meropenem sales were stable. Conclusion: The results underscore the need for timely routine antimicrobial susceptibility testing of B. fragilis group species and questions piperacillin-tazobactam monotherapy as empiric treatment for septic patients with a suspected abdominal source.

Original languageEnglish
JournalInfectious Diseases
ISSN2374-4235
DOIs
Publication statusE-pub ahead of print - 22. Nov 2024

Bibliographical note

Publisher Copyright:
© 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

Keywords

  • anaerobic bacteria
  • antimicrobial susceptibility testing
  • Bacteraemia
  • Bacteroides
  • resistance

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