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目的分析广州地区大肠埃希菌对喹诺酮类等12种抗菌药物耐药性,探讨qnr、qepA、aac-(6′)-Ib-cr质粒基因流行状况以及与耐药的关系。方法收集广州市两所三甲医院临床分离大肠埃希菌103株,采用纸片扩散法进行药敏试验,采用PCR技术检测大肠埃希菌中qnr(qnrA、qnrB、qnrS)、aac-(6′)-Ib-cr和qepA质粒基因,并对PCR产物进行DNA测序分析。结果 103株大肠埃希菌对喹诺酮类抗菌药物的耐药率均>50.0%,20株菌检出阳性基因qnrB、qnrS、aac(6′)-Ib-cr的阳性率分别为9.7%、7.8%、10.7%,有8株菌同时携带≥2种质粒基因,这8株菌对喹诺酮类药物全部耐药,同时合并其他类抗菌药物耐药,其中52号菌同时携带3种基因[qnrB、qnrS、aac-(6′)-Ⅰb-cr],对6类抗菌药物全部耐药,12株菌检出单个质粒基因,其中4株对喹诺酮类敏感。结论广州市大肠埃希菌对喹诺酮类抗菌药物耐药率居高不下;药敏谱呈多样化,多药耐药株比例高;菌株中存在qnrB、qnrS、aac-(6′)-Ⅰb-cr的流行,并呈现出两种或多种耐药基因共存于同一株细菌的特征;质粒介导的喹诺酮耐药基因数量与耐药种类数量呈正相关。
Objective To analyze the resistance of Escherichia coli to quinolones and other antimicrobial agents in Guangzhou and to explore the prevalence of qnr, qepA, aac- (6 ’) - Ib-cr and their relationship with drug resistance. Methods 103 clinical isolates of Escherichia coli isolated from two top three hospitals in Guangzhou were collected and drug susceptibility tests were performed by disk diffusion method. The levels of qnr (qnrA, qnrB, qnrS), aac- (6 ’ ) -Ib-cr and qepA plasmid genes, and PCR products of DNA sequencing analysis. Results The positive rates of qnrB, qnrS and aac (6 ’) - Ib-cr in 20 isolates of Escherichia coli were all above 50.0% %, 10.7%, 8 strains carrying more than two kinds of plasmid genes at the same time, these 8 strains are all resistant to quinolones and resistant to other antibacterial drugs. Among them, 52 strains carry three genes [qnrB, qnrS, aac- (6 ’) - Ib-cr] were all resistant to 6 kinds of antibacterials, and 12 strains were single plasmids, of which 4 were sensitive to quinolones. Conclusion The resistant rate of Escherichia coli to quinolone antibiotics in Guangzhou is high. The drug susceptibility spectrum is diversified and the proportion of multidrug-resistant strains is high. There are qnrB, qnrS, aac- (6 ’) - Ⅰb- cr, and showed the coexistence of two or more resistant genes in the same strain of bacteria. The number of plasmid-mediated quinolone resistance genes was positively correlated with the number of resistant species.