【摘要】 目的调查大肠埃希菌分离株的耐药特征及质粒介导喹诺酮耐药基因流行状况。方法纸片扩散(K-B)法进行药物敏感试验,采用双纸片法检测产超广谱β内酰胺酶(ESBL),聚合酶链反应(PCR)检测qnr A、qnr B、qnr C、qnr D、qnr S、aac(6’)-Ib、qep A基因,限制性酶切反应确定aac(6’)-Ib-cr基因型。结果 179株大肠埃希菌中95株ESBL表型确证试验阳性,检出率为53.1%;产ESBL菌株未见对美罗培南耐药,对亚胺培南耐药率极低(1.1%),对阿米卡星、哌拉西林-他唑巴坦、头孢哌酮-舒巴坦耐药率皆低于30%,对哌拉西林、头孢噻肟、头孢曲松、氨曲南、甲氧苄啶-磺胺甲唑耐药率皆高于70%,对庆大霉素、头孢他啶、环丙沙星、左氧氟沙星耐药率在60%~70%;PCR扩增结果显示产ESBL菌株,具有qnr基因9株(9.5%),其中qnr A 2株、qnr B 5株、qnr S 2株。非产ESBL菌株,具有qnr B基因3株(3.6%);酶切反应显示产和非产ESBL菌株具有aac(6’)-Ib-cr基因分别为21株(22.1%)和5株(6.0%)。所有菌株皆未检测到qep A基因。结论产ESBL大肠埃希菌呈现多重耐药趋势,质粒介导喹诺酮耐药基因以aac(6’)-Ib-cr基因型为主。更多还原

【Abstract】 Objective To investigate the resistance profile and the prevalence of plasmid-mediated quinolone resistance(PMQR) genes in Escherichia coli isolates. Methods Antimicrobial susceptibility testing was conducted by Kirby-Bauer method. Double disc method was used to detect extended-spectrum Beta-lactamases(ESBLs) phenotypically. The qnr A, qnr B, qnr C, qnr D, qnr S, aac(6’)-Ib, and qep A genes were identified by polymerase chain reaction(PCR). The aac(6’)-Ib-cr gene was confirmed by restriction endonuclease reaction. Results The overall prevalence of ESBLs-producing strains was 53.1%(95/179) in Escherichia coli isolates. The ESBLs-producing strains showed no resistance to meropenem and the lowest resistance rate(1.1%) to imipenem, followed by amikacin, piperacillin-tazobactam, and cefoperazone-sulbactam(16.8%, 24.2%, and 29.5% resistant respectively). More than 70% of the ESBLs-producing strains were resistant to piperacillin, cefotaxime, ceftriaxone, aztreonam, and trimethoprim-sulfamethoxazole, while 60%-70% were resistant to gentamicin, ceftazidime, ciprofloxacin, levofloxacin and levofloxacin. PCR results showed that qnrgene was identified in 9(9.5%) of the ESBLs-producing E. coli strains, including qnr A in 2 strains, qnr B in 5 strains and qnr S in 2 strains. And qnr B gene was identified in 3(3.6%) non-ESBLs-producing E. coli strains. Restriction endonuclease reaction revealed that aac(6’)-Ib-cr gene was positive in 21(22.1%) ESBLspositive strains and 5(6.0%) ESBLs-negative E. coli strains, respectively. qep A gene was not identified in any isolate. Conclusions ESBLs-producing E. coli showed resistance to multiple antimicrobial agents. aac(6’)-Ib-cr is the primary genotype of PMQR.更多还原