JAC Advance Access originally published online on August 10, 2006
Journal of Antimicrobial Chemotherapy 2006 58(4):789-793; doi:10.1093/jac/dkl338
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In vitro activity of linezolid against clinical isolates of Fusobacterium spp.
1 Institute for Medical Microbiology, Martin-Luther-University Halle-Wittenberg Halle/Saale, Germany 2 Department for Hygiene and Medical Microbiology, Medical University of Vienna Vienna, Austria 3 Institute for Hygiene and Environmental Medicine, Ernst-Moritz-Arndt University Greifswald, Germany
Received 26 May 2006; returned 6 July 2006; revised 8 July 2006; accepted 26 July 2006
*Corresponding author. Tel: +43-1-40400-1904; Fax: +43-1-40400-1907; E-mail: ojan.assadian{at}meduniwien.ac.at
Objectives: Although most susceptibility studies for linezolid have investigated aerobic bacteria, only a few have investigated anaerobe isolates. The aim of the present study was to determine the antibacterial activity of linezolid against a larger sample of clinical isolates of Fusobacterium spp. and to report on the detailed susceptibility, stratified by species.
Methods: The in vitro susceptibility of 80 clinical isolates of Fusobacterium (Fusobacterium necrophorum, n = 34; Fusobacterium nucleatum, n = 20; Fusobacterium varium, n = 18; Fusobacterium mortiferum; n = 8) was tested and compared with the activity of the older compounds amoxicillin and amoxicillin/clavulanic acid.
Results: The MIC of linezolid ranged from 0.016 to 1.0 mg/L, with the MIC90 being 0.5 mg/L. The highest MIC obtained for linezolid (1.0 mg/L) was measured for an F. varium isolate. The MIC90 for both, amoxicillin (range: 0.0160.75 mg/L) and amoxicillin/clavulanic acid (range: 0.0470.75 mg/L), was 0.5 mg/L. Overall, no resistant strains were found in the study.
Conclusions: Compared with amoxicillin and amoxicillin/clavulanic acid, linezolid was less active against F. necrophorum (MIC90 0.25 mg/L) and F. nucleatum (MIC90 0.25 mg/L), equally active against F. varium (MIC90 0.75 mg/L) and slightly more active against F. mortiferum (MIC90 0.19 mg/L).
Keywords: anaerobic bacteria , susceptibility , MIC , resistance , amoxicillin , amoxicillin/clavulanic acid