氟喹诺酮耐药志贺菌中质粒介导qnr基因的检测

The determination of plamid-mediated qnr gene in quinolone-resistant Shigella

目的检测志贺菌对氟喹诺酮抗菌药物的耐药情况,探讨氟喹诺酮耐药与志贺菌携带质粒介导qnr基因的关系。方法用纸片扩散法对100株志贺菌(福氏志贺菌50株,宋内志贺菌50株)进行耐药性检测,聚合酶链反应(PCR)检测志贺菌质粒介导qnr基因并进行DNA测序,分析qnr基因的存在与药敏结果的关系。结果 100株志贺菌中有9株检出qnr基因,检出率为9%(9/100),福氏志贺菌为4%(2/50),宋内志贺菌为14%(7/50);qnr基因阳性菌株对氧氟沙星的耐药率(11.1%)高于阴性菌株(5.5%),但差异无统计学意义。qnr基因阳性菌株对5种氟喹诺酮药物的抑菌圈中位数比较均缩小。结论宋内志贺菌质粒介导氟喹诺酮耐药qnr基因的携带率明显高于福氏志贺菌;志贺菌若携带质粒介导qnr基因则会导致对氟喹诺酮药物的敏感性下降。

Objective To investigate the quinolone-resistance of Shigella isolates and its relationship with the plamid-mediated qnr gene.Methods A total of 100 Shigella isolates were collected.50 isolates were Shigella flexneri,and 50 isolates were Shigella sonnei.The drug resistance was determined by disc diffusion method.The qnr gene was detected by polymerase chain reaction（PCR）.The qnr gene segments were amplified and sequenced to analyze the correlation between quinolone-resistance and the presence of qnr gene.Results The qnr gene was identified in 9（9%）of the 100 Shigella isolates,2（4%）of the 50 Shigella flexneri and 7（14%） of the 50 Shigella sonnei.The resistance rate of ofloxacin in qnr positive isolates（11.1%） was higher than that in qnr negative isolates（5.5%）,but there was no statistical significance.The median diameters of 5 quinolone inhibition zones of the isolates with qnr gene were smaller than those without qnr gene.Conclusions The plamid-mediated qnr gene in Shigella sonnei isolates is more than that in Shigella flexneri isolates.The plamid-mediated qnr gene of Shigella isolates can decrease the resistance rate of quinolone.