摘要
为探究牛源非O157产志贺毒素大肠埃希菌(STEC)的耐药基因与毒力基因是否发生共转移,本研究采用PCR方法对29株牛源非O157 STEC利用"Top six"血清群筛查、系统进化分群和毒力基因检测,结果显示31.03%(9/29)STEC为O145血清群;系统进化分群以A群为主(68.97%);75.86%(22/29)STEC的毒力基因谱为stx1a+stx2a+ehxA。采用K-B法测定STEC的抗生素敏感性,通过PCR及测序检测耐药基因bla TEM、bla CTX、bla SHV、tetA、tetE、tetG、sulI、cmlAI、aadAI和aac(3)-IV,利用多重PCR方法对耐药菌进行质粒分型、接合试验确认耐药基因和毒力基因是否发生水平转移。结果显示,29株STEC对四环素、复方新诺明、氯霉素、链霉素、氨苄西林、头孢噻肟、头孢他啶和氨曲南的耐药率在13.79%~27.59%,对庆大霉素、哌拉西林、阿莫西林/克拉维酸、氨苄西林-舒巴坦和阿米卡星的耐药率在6.90%~10.34%。共检测出8株耐药菌(27.59%),且均呈多重耐药表型,对4~13种抗生素耐药。8株耐药菌均携带四环素耐药基因tetA(未检测出其他耐药基因)和质粒incA/C并可转移至受体菌E. coli J53,其中6株可将毒力基因stx1a、stx2a和ehxA共转移至E. coli J53。以上结果表明牛源非O157 STEC存在较严重的耐药情况。本研究首次揭示耐药基因和毒力基因在非O157 STEC中发生共转移,为进一步研究二者共转移机制奠定基础。
To investigate whether the drug resistance genes and virulence genes of bovine non-O157 STEC could be cotransferred, "Top six" serogroups, phylogenetic group and virulence genes screening of 29 bovine non-O157 STEC isolates were performed by PCR. The results showed that 31.03%(9/29) of STEC strains belonged to O145 serogroup, the majority of isolates belonged to phylogenetic group A(68.97%), and 75.86%(22/29) of the virulence gene profile was stx1 a+stx2 a+ehxA. Anti-microbial susceptibility test was performed by Kirby Bauer-disk diffusion method, and the resistance genes of blaTEM, blaCTX, blaSHV, tet A, tet E,tet G, sul I, cma I, aad AI and aac(3)-IV were detected by PCR and DNA sequencing methods. Plasmid carried by drug-resistant bacteria were classified by multiplex PCR method and the horizontal transfer of resistant and virulent genes was con-firmed by conjugation tests. The drug resistance rates of the 29 isolates to tetracycline, cotrimoxazole, chloramphenicol, strepto-mycin,ampicillin, cefotaxime, ceftazidime, and aztreonam ranged from 13.79% to 27.59%, to gentamicin, piperacillin, amoxicillin/clavulanic acid, ampicillin-sulbactam, and amikacin ranged from 6.90% to 10.34%. A total of 8 drug-resistant strains(27.59%)were detected, all of which showed multiple drug-resistant phenotypes and were resistant to 4 to 13 antibiotics. All the 8 multi-drug resistant strains carried tetracycline resistant gene tet A(no other antimicrobial resistance genes were detected) and plasmid inc A/C,and could be transferred to E. coli J53, among which 6 strains could transfer virulence genes stx1 a, stx2 aand ehx A to E. coli J53. The above results indicated that non-O157 STEC of bovine origin had serious drug resistance. This study reveals for the first time that drug resistance genes and virulence genes co-transfer in non-O157 STEC, which lays a foundation for further research on the cotransfer mechanism of the two genes.
作者
佟盼盼
张凌
谢金鑫
张萌萌
唐雪林
张毅
夏利宁
苏战强
TONG Pan-pan;ZHANG Ling;XIE Jin-xin;ZHANG Meng-meng;TANG Xue-lin;ZHANG Yi;XIA Li-ning;SU Zhan-qiang(College of Animal Medicine,Xinjiang Agricultural University,Urumqi 830052,China)
出处
《中国预防兽医学报》
CAS
CSCD
北大核心
2021年第8期820-825,共6页
Chinese Journal of Preventive Veterinary Medicine
基金
国家自然科学基金(31960695)
自治区高层次人才引进工程项目
新疆农业大学博士后科研流动站资助
自治区天山创新团队(2020D14005)。
