多重耐药鸡源大肠杆菌EC86菌株耐药基因鉴定及耐药机制分析OA

This study aimed to elucidate the resistance mechanisms of a multidrug-resistant Escherichia coli strain EC86 isolated from the livers of diseased and deceased chickens in Zunyi,Guizhou Province.Strain EC86 was identified as Escherichia coli via BLAST alignment of the 16S rRNA gene sequence.The results of antimicrobial susceptibility testing using the agar doubling dilution method showed that this strain was resistant to a variety of antibiotics,with remarkable resistance particularly to penicillins,quinolones,and tetracyclines.Whole-genome sequencing analysis revealed that the chromosome of EC86 was 5,033,242 bp in size,and it harbored one resistance plasmid of 269,290 bp.This plasmid carried 15 resistance genes,among which the presence of broad-spectrum β-lactamases blaTEM-1 and blaCTX-M-55 may have enhanced the resistance of EC86 to penicillins,while the presence of QnrS1 may have improved its resistance to quinolones.