摘要
15株动物源性耐氟喹诺酮类药物大肠杆菌进行PCR检测、测序、WDNASIS软件分析gyrA基因中的氟喹诺酮耐药决定区(QRDR)、AcrA以及编码与质粒介导的氟喹诺酮类药物耐药机制相关的qnrA、qnrB、qnrS、qepA和aac(6′)-Ib-cr基因。结果表明,15株耐药菌中,QRDR基因在其编码第72、75、83位或第87位氨基酸均发生突变;AcrA基因未检测到氨基酸的突变;qnrS、qepA和aac(6′)-Ib-cr耐药基因阳性菌各检测到1株,序列分析表明不存在氨基酸突变。QRDR基因编码的氨基酸4个位点发生突变,其中Ser83→Leu和Asp87→Asn 2个基因的突变均与文献报道的突变相同,双突变的7个菌株均表现为高度耐氟喹诺酮类抗生素,表明gyrA基因为大肠杆菌耐氟喹诺酮类抗生素的一个重要机制。高度耐氟喹诺酮类抗生素的菌株中有2株没有检测到氨基酸突变的存在,但是aac-(6′)-Ib-cr基因和qnrS检测为阳性,表明质粒介导的喹诺酮类耐药也可单独导致菌株的耐药。存有一个菌株gyrA基因编码的氨基酸发生突变Ser83→Leu,AcrA基因和qnrA、qnrB、qnrS、qepA和aac(6′)-Ib-cr基因检测均为阴性,但是菌株仍然表现为高度耐药,说明还有未知的耐药机制存在。
Quinolone-resistant determining region（QRDR） of gyrA gene,AcrA of Escherichia coli and plasmid-mediated fluoroquinolones resistance gene,qnrA,qnrB,qnrS,qepA and aac（6′）-Ib-cr of 15 clinical isolates of antibiotic-resistant Escherichia coli were detected,sequenced and analyzed by WDNASIS.The results indicated that,the nucleotides were mutated at the sites 72,75,83 and 87 of QRDR.No mutation was detected in the gene of AcrA.The drug resistance gene of qnrS,qepA and aac（6′）-Ib-cr all showed one positive strain,and the sequence analyzsis indicated no amino acids was mutated.There were 4 mutations in the amino acids which coded by QRDR,Ser83→Leu and Asp87→Asn were agreed with the mutations reported by documents.The 7 mutated strains were highly tolerant of fluoroquinolone,indicating gyrA was important for antibiotic-resistant Escherichia coli.The 2 strains in highly tolerant fluoroquinolone strains,were not found with mutation of amino acids.But aac-（6′）-Ib-cr and qnrS were positive which indicated that plasmid-mediated fluoroquinolones resistance gene could lead to resistance along.Ser83→Leu was detected positively in only one amino acid coded by gyrA,and AcrA,qnrA,qnrB,qnrS,qepA and aac（6′）-Ib-cr were negative.But the strain was still highly resistance,which indicated that the mechanism of resistance still uncovered completely.
出处
《中国兽医学报》
CAS
CSCD
北大核心
2011年第6期875-879,共5页
Chinese Journal of Veterinary Science
基金
"十一五"国家科技支撑计划资助项目(2008BADB4B04)
