解脲脲原体对氟喹诺酮类药物耐药性研究

Study on fluroquinolones resistance and GyrA resistance gene mutation of ureaplasma urealyticum

目的探讨解脲脲原体对氟喹诺酮类药物的耐药状况与gyrA基因突变之间的关系。方法对鉴定确认的解脲脲原体临床分离株,采用微量肉汤稀释法检测其环丙沙星、氧氟沙星和左旋氧氟沙星的最小抑菌浓度(MIC),随机抽取28株菌株,PCR扩增gyrA基因并测序,采用Blast比对法分析临床菌株与标准菌株的序列差异。结果解脲脲原体的环丙沙星、氧氟沙星和左旋氧氟沙星MIC50分别为8,4和2 mg/L;MIC90分别为64,16和8 mg/L;在28株解脲脲原体菌株中,经测序分析发现gyrA基因3种突变形式:(1)101位丙氨酸改变为缬氨酸;(2)112位天冬氨酸改变为谷氨酸;(3)267位碱基T缺失。具有基因突变的菌株其MIC明显高于没有突变的菌株。结论江苏省部分地区解脲脲原体对第1、2代氟喹诺酮类药物耐药严重,此类药物不再适用于治疗解脲脲原体感染;解脲脲原体对氟喹诺酮类药物的耐药主要是由于gyrA基因突变导致相应氨基酸改变所介导。

Objective To study the status of fluoroquinolones resistance and GyrA gene mutation of U. urealytieum. Methods In vitro 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. Results For U. urealyticum the MIC50 of ciprofloxacin, ofloxacin and levofloxacin were 8, 4 and 2 mg/L respectively;Their MIC50 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 gluramine substitution at position 112; （3） An absence of T base at position 267. U. urealyticum with GyrA alterations was more resisrant to fluoroquinolones. Conclusion Most of U. urealyticum isolated from Jiangsu province are resistant to ciprofloxacin, ofloxacin, and levofloxacin, and these three antibiotics should not used to treat irdection of U. urealyficum. Resistance of U. urealyticum to fluroquinolones is mainly due to alterations of GyrA.