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T. Katome, H. Eguchi, T. Kuwahara, H. Shiota, T. Miyamoto; Relationship Between Susceptibility to Quinolones in Corynebacterium Ophthalmic Clinical Isolates and the GyrA Gene Mutations. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1982.
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© ARVO (1962-2015); The Authors (2016-present)
Toinvestigate the relationship between minimal inhibitory concentrations (MICs) of LVFX, GFLX and MFLX against ophthalmic clinical isolates of Corynebacterium with amino acid exchange in the gyrA genes.
Forty-three strains of Corynebacterium, including five strains that have differences among susceptibilities to three quinolones, were collected from 12 eye institutes in Japan are involved in this study. The species assignment of these isolates was made by the sequence analysis of the 16S ribosomal RNA gene (rDNA). The genomic DNA of each strain grown in brain heart infusion broth containing 0.1% Tween 80 was purified and the QRDRs of the gyrA gene were analyzed. MICs were tested with E-test .
The MICs of GFLX and MFLX are approximately equivalent and those of LVFX are higher than the formers in all Corynebacterium. All the strains that have high-level resistance to the three quinolones (MIC>32µg/ml) possess double mutations generating changes in Ser-83 and Asp-87. Three strains that are susceptible to GFLX and MFLX, despite they have high-level resistance or intermediate to LVFX, are found. They possess amino acid changes of Ser83 to Leu or Arg and Asp87 to Asn. Two strains that are intermediate (MIC=4µg/ml) or susceptible (MIC=2µg/ml) to GFLX, despite they have high-level resistant or intermediate to LVFX (MIC>32µg/ml) or MLFX (MIC=8µg/ml), possess amino acid changes of Ser83 to Ala and Asp87 to Tyr.
This study strongly indicates that there is a relationship between MICs of quinolones against ophthalmic clinical isolates of Corynebacterium and amino acid exchange in the gyrA genes.
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