Journal Article

Plasmid-mediated complementation of <i>gyr</i>A and <i>gyr</i>B in fluoroquinolone-resistant <i>Bacteroides fragilis</i>

M. L. Peterson, J. C. Rotschafer and L. J. V. Piddock

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 52, issue 3, pages 481-484
Published in print September 2003 | ISSN: 0305-7453
Published online September 2003 | e-ISSN: 1460-2091 | DOI:
Plasmid-mediated complementation of gyrA and gyrB in fluoroquinolone-resistant Bacteroides fragilis

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Objectives: To identify whether mutations in gyrA and gyrB confer fluoroquinolone resistance in Bacteroides fragilis.

Methods: Eight fluoroquinolone-resistant (FQR) strains were complemented with plasmid-mediated B. fragilis wild-type gyrA (pMP1) and gyrB (pMP2), and MICs determined. Sequence analysis of the gyrA and gyrB quinolone resistance determining region (QRDR) was performed for all strains.

Results: MICs of fluoroquinolones were two- to 32-fold higher than wild-type for all mutants. Five mutants had a substitution in GyrA (Ser-82→Phe), one mutant had a substitution in GyrA (Asp-81→Gly), one mutant had a substitution in GyrB (Glu-478→Lys), and one resistant strain did not contain mutations in the QRDR of gyrA or gyrB. Following complementation with pMP1 or pMP2, the MICs of fluoroquinolones were reduced two- to 32-fold for the mutants.

Conclusion: These studies verify that substitutions in GyrA and GyrB confer resistance in B. fragilis. Other mechanisms are also responsible for resistance since not all resistant strains fully complemented to the wild-type phenotype.

Keywords: Keywords: anaerobe, quinolone, antibiotic resistance

Journal Article.  2327 words. 

Subjects: Medical Oncology ; Critical Care

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