Abstract: ObjectiveTo study the status of fluoroquinolones resistance and GyrA gene mutation of U.urealyticum.MethodsIn vit ro susceptibilities(Minimum inhibitory concentration,MIC)to ciprofloxacin,ofloxaxin and levofloxacin of 84 U.urealyticum strains from clinical patients were determined by a broth microdilution method.Specific fragments of gyrA genes of randomly selected 28 strains were amplified by PCR and sequenced.Blast program was used to analyze and compare the sequence of clinical isolates with standard strain T3.ResultsFor U.urealyticum the MIC₅₀ of ciprofloxacin,ofloxacin and levofloxacin were 8,4 and 2 mg/L respectively;Their MIC90 were 64,16 and 8 mg/L respectively.Three alterations of GyrA in 28 U.urealyticum strains were found:(1)A alanine to valine substitution at position 101;(2)A aspartic acid to glutamine substitution at position 112;(3)An absence of T base at position 267.U.urealyticum with GyrA alterations was more resistant to fluoroquinolones.ConclusionMost of U.urealyticum isolated from Jiangsu province are resistant to ciprofloxacin, ofloxacin,and levofloxacin,and these three antibiotics should not used to treat infection of U.urealyticum.Resistance of U.urealyticum to fluroquinolones is mainly due to alterations of GyrA.