Development of EUCAST disk diffusion method for susceptibility testing of the Bacteroides fragilis group isolates

on behalf of ESCMID Study Group on Anaerobic Infection

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

With the emergence of antibiotic resistance among Bacteroides fragilis group isolates the need of susceptibility testing in routine laboratories is increasing. The aims of the present study were to evaluate the disk diffusion method for susceptibility testing in case of different clinical isolates of Bacteroides spp by comparing zone diameter results with MICs obtained earlier during an Europe-wide antibiotic susceptibility surveillance, and to propose zone diameter breakpoints, which correlate for the EUCAST MIC breakpoints. We tested 381 clinical isolates of the B.fragilis group to amoxicillin/clavulanic acid, cefoxitin, clindamycin, imipenem, metronidazole, moxifloxacin, piperacillin/tazobactam, tigecycline by agar dilution method previously. The inhibition zones of the same antibiotics including meropenem disc were determined by the disc diffusion on Brucella blood agar supplemented with haemin and vitamin K1. Plates were incubated at 37°C in an anaerobic atmosphere for 24h. The zone diameters were read at 100% inhibition. In case of discrepant results MICs were determined by gradient test and compared with the inhibition zones on the same plate. We found a good agreement between the inhibition zone diameters and the MICs for imipenem, metronidazole, moxifloxacin and tigecyclin. The inhibition zone diameters of meropenem also separated clearly the isolates, which can be considered wild-type isolates. In case of amoxicillin/clavulanic acid and piperacillin/tazobactam intermediate and susceptible isolates according to the MIC determination, overlap during the zone diameter determination. Isolates with an inhibition zone

Original languageEnglish
Pages (from-to)65-71
Number of pages7
JournalAnaerobe
Volume31
DOIs
Publication statusPublished - Feb 1 2015

Fingerprint

meropenem
Amoxicillin-Potassium Clavulanate Combination
Bacteroides fragilis
Imipenem
Metronidazole
Agar
Vitamin K 1
Anti-Bacterial Agents
Cefoxitin
Hemin
Brucella
Bacteroides
Clindamycin
Microbial Drug Resistance
Atmosphere
moxifloxacin
tazobactam drug combination piperacillin

Keywords

  • Bacteroides fragilis group
  • Breakpoints
  • Disc diffusion
  • MIC determination
  • Susceptibility testing

ASJC Scopus subject areas

  • Microbiology
  • Infectious Diseases
  • Medicine(all)

Cite this

Development of EUCAST disk diffusion method for susceptibility testing of the Bacteroides fragilis group isolates. / on behalf of ESCMID Study Group on Anaerobic Infection.

In: Anaerobe, Vol. 31, 01.02.2015, p. 65-71.

Research output: Contribution to journalArticle

on behalf of ESCMID Study Group on Anaerobic Infection. / Development of EUCAST disk diffusion method for susceptibility testing of the Bacteroides fragilis group isolates. In: Anaerobe. 2015 ; Vol. 31. pp. 65-71.
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