2.4. Analysis of gyrA mutations.

The QRDR of gyrA gene (triplet 19 to 192) was amplified by PCR with primers 32fw (5’-ATATTGTAGAAGTGGGGATTGAT-3’) and 600rv (5’-ATGCACTAAAGCGTCTATGATT-3’) (18) using Q5 Hot Start High-Fidelity DNA Polymerase (New England Biolabs) as described by the manufacturer. The protocol for thermalcycler was as follows: initial denaturation of 98°C / 3 minutes, 35 cycles of 98°C / 10 seconds + 60°C / 30 seconds + 72°C / 30 seconds, and final extension of 72°C / 2 minutes. The PCR product was electrophoresed in a 1.5% agarose gel and the 569bp fragment purified using Monarch DNA Gel Extraction Kit (New England Biolabs). The sequence of the amplicon was obtained by Sanger sequencing (Service provided by Macrogen Inc., Korea).