The relationship between gyrA and parC gene mutations of Klebsiella pneumoniae and quinolone resistance

[Objective] To analyze the relationship between the mutations in the quinolone-resistance-determining-region(QRDR)of gyrA and parC genes and the quinolone resistance in K.pneumoniae isolates.[Method] The MICs of 3 quinolone-drugs were determined.PCR and DNA sequencing were conducted to analyze QRDR associated genes of gyrA and parC in 26 isolates.[Result]The resistance rate of the 87 isolates were 58.6%,55.2% and 51.7% to norfloxacin,ciprofloxacin and levofloxacm,respectively.In gyrA gene,all 16 resistant isolates had mutation of S83.9 of 16 resistant isolates had mutation of S80 with MICs ranging from 16 to ≥128mg/L.7 of 16 resistant isolates were not found mutation of S80 with MICs ranging from 4 to 32.[Conclusion] Mutations in gyrA and parC genes play an important role in the development of quinolone resistance in K.pneumoniae.Mutation of S80 in parC gene are closely associated with high quinolone-resistance.