gyrA和parC基因与粪肠球菌对氟喹诺酮类抗菌药物耐药的关系

Relationship between gyrA and parC genes and Enterococcus faecalis to fluoroquinolone resistance

目的探讨粪肠球菌DNA解旋酶和拓扑异构酶Ⅳ基因与氟喹诺酮类抗菌药物的耐药的关系,为临床治疗和新药的开发提出实验依据。方法用琼脂稀释法检测112株粪肠球菌对4种氟喹诺酮类抗菌药物的体外敏感试验,并选择对氟喹诺酮类抗菌药物耐药的菌株对其gyrA和parC的喹诺酮耐药决定区域基因进行PCR扩增,然后随机选择5株PCR产物纯化后直接测序经基因同源性分析(BLAST)分析其氨基酸序列。结果 4种氟喹诺酮类抗菌药物对粪肠球菌的抑菌效果依次为:加替沙星>左氧氟沙星>诺氟沙星、环丙沙星;5株菌的gyrA基因有4株第83位氨基酸发生了改变,parC基因均发生了突变。结论粪肠球菌对氟喹诺酮类药物的耐药情况严重,gyrA基因和parC基因的氨基酸突变是引起粪肠球菌对氟喹诺酮类抗菌药物产生耐药的重要原因。

Objective To study DNA gyrase and topoisomerase Ⅳ gene mutation to fluoroquinolone resistance and provide experimental evidence in treatment for clinical and developing new drugs.Methods Detected by agar dilution method against 112 strains of Enterococcus faecalis 4 fluoroquinolone antibiotics in vitro susceptibility testing,and PCR amplified QRDR of gyrA and parC that quinolone resistant strains,Then randomly selected 5 direct sequencing of PCR products were purified and compared by BLAST analysis of its amino acid sequence.Results 4 fluoroquinolone antibiotics against E.faecalis on the antibacterial activity as follows： GATLVXNOR and CIP.GyrA gene had changed with Ser83→Ile（AGT→ATT）and Ser83→Tyr（AGT→TAT）;parC genes occurred mutation with Ser80→Ile（AGC→ATC）,Ser48→Leu（TCA→TTA）,Met89→Leu（ATG→CTA）,Lys94→Ile（AAG→ATA）.Conclusion Enterococcus faecalis resistant to fluoroquinolones in serious condition.The mutation of gyrA and parC gene is an important reason of E.faecalis resistant to fluoroquinolone antibiotics.