禽源大肠杆菌多重耐药机制初探

Preliminary Study on Multi-drug Resistant Mechanism of Avian Escherichia coli Isolates

为了解禽源性大肠杆菌的多重耐药机制,对禽临床样品分离株进行了药敏试验、多重耐药调控基因soxS基因及氟喹诺酮类耐药基因检测。药敏试验结果显示,从禽临床样品分离出的12株大肠杆菌中,6株对氟喹诺酮类抗菌药物耐药,11株对氨基糖苷类抗菌药物耐药,12株对四环素类抗菌药物耐药和酰胺醇类耐药。PCR检测结果显示,12株禽源大肠杆菌均携带soxS基因,表明禽源大肠杆菌多重耐药与soxS基因关系密切。序列分析结果显示,7株大肠杆菌soxS基因无突变,4株存在点突变并导致A12S替换,2株soxS突变菌株同时携带氟喹诺酮类耐药基因qnrS。因此,12株禽源大肠杆菌具有多重耐药性,可能与soxS基因调控相关,突变株的出现增强了氟喹诺酮类的耐药性。

In order to deterrmine the multi-drug resistance mechanism in Escherichia coli of avian origin,isolates from avian clinical samples were subjected to drug susceptibility,multi-drug resistance regulatory gene soxS and fluoroquinolone resistance gene testing.The drug susceptibility test revealed that among 12 avian E.coli strains isolated,6,11 and 12 strains were resistant to fluoroquinolone,aminoglycoside,and both tetracycline and florfenicol,respectively.The PCR results showed that the 12 strains carried the soxS gene,indicating a possible link between E.coli multi-drug resistance and the presence of the soxS gene.Sequence analysis confirmed that 7 strains harbored no mutation in the soxS gene,4 strains had point mutations in the soxS gene leading to A12S substitution underlying fluoroquinolone resistance,and 2 strains with soxS mutation also contained fluoroquinolone resistance gene qnrS.These results indicate that E.coli multi-drug resistance may be related to the dysregulation of the soxS gene,as E.coli strains harboring soxS mutations display increased resistance to fluoroquinolone.