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Article Dans Une Revue International Journal of Antimicrobial Agents Année : 2009

In vitro selection of fluoroquinolone resistance in Brucella melitensis.

Résumé

Moxifloxacin-resistant mutants of Brucella melitensis 16M [moxifloxacin minimum inhibitory concentration (MIC)=1mg/L] were selected in order to characterise fluoroquinolone resistance mechanisms in this species. Eight independent mutants were obtained, with moxifloxacin MICs of 16-32mg/L. The mutants displayed variable cross-resistance levels to other fluoroquinolone compounds, but no increased resistance to aminoglycosides, tetracycline, rifampicin, macrolides or co-trimoxazole. Sequencing of type II topoisomerase-encoding genes (gyrA, gyrB, parC and parE), which are natural targets for fluoroquinolones, revealed a gyrA mutation leading to the amino acid substitution Ala83Val (Escherichia coli numbering system) in five mutants with a moxifloxacin MIC of 32mg/L, whereas no mutation was found in the remaining three mutants with a MIC of 16mg/L. Phenylalanine-arginine-beta-naphthylamide dihydrochloride, an efflux pump inhibitor, reduced moxifloxacin MICs by a factor of two to eight in all resistant mutants. In B. melitensis, fluoroquinolone resistance may arise from gyrA mutation and efflux pump overexpression mechanisms.

Dates et versions

hal-00409936 , version 1 (14-08-2009)

Identifiants

Citer

N. Ravanel, B. Gestin, M. Maurin. In vitro selection of fluoroquinolone resistance in Brucella melitensis.. International Journal of Antimicrobial Agents, 2009, 34 (1), pp.76-81. ⟨10.1016/j.ijantimicag.2009.01.002⟩. ⟨hal-00409936⟩

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