宠物源大肠杆菌中质粒介导喹诺酮类耐药基因qnrD的研究

New Plasmid-Mediated Quinolone Resistance Gene qnrD Found in an Isolate of Escherichia coli from Pet Animals

【目的】对临床分离的宠物源大肠杆菌进行质粒介导喹诺酮类耐药基因qnrD的检测,并对该基因进行序列分析和传播机制的研究。【方法】采用微量稀释法对阳性菌株进行15种抗生素的最小抑菌浓度试验;通过PCR对基因克隆,并对克隆产物和菌株阳性质粒进行转化;同时对菌株进行接合转移试验。【结果】从164株宠物源大肠杆菌中检测出1株qnrD阳性菌株(GP2009-036),GP2009-036对14种兽医临床常用抗生素耐药严重,表现为多重耐药(14耐);PCR产物经连接PMD19-T载体后可转化入DH5α感受态细胞中;接合转移试验成功地将质粒转移到大肠杆菌J53中;可从GP2009-036与其转化子中抽提出阳性质粒。【结论】该qnrD阳性菌株对临床常用抗生素耐药严重,且阳性质粒可在病原微生物间进行水平传播,其水平传播机制可能使该基因在宠物临床上进行传播。

【Objective】The objective of this study is to detect plasmid-mediated quinolone resistance qnrD gene in clinical isolates of Escherichia coli from pet animals,analyze the sequence of this gene and study the transmission mechanism of qnrD gene. 【Method】Susceptibility of positive strain to 15 antimicrobial agents was determined by micro-dilution method;PCR method was used for cloning qnrD gene,clone products and positive plasmid were used for transmission tests,and conjugation experiments were made.【Results】One（GP2009-036） of the 164 specimens was detected containing qnrD gene,GP2009-036 showed high rate of resistance to 14 antimicrobial agents widely used in veterinary clinical medicine and showed multiple-resistance（14 drugs） .PCR products connected with PMD19-T vector could be transformed into DH5αcompetent cells.The positive plasmid were transmitted into Escherichia coli J53 successfully by conjugation experiments and the positive plasmid could be extracted from GP2009-036 and transconjugants.【Conclusion】This qnrD positive strain of Escherichia coli showed high rate of resistance to antimicrobial agents widely used in veterinary clinical medicine,and the positive plasmid can transmit among pathogenic microorganism,and the mechanism of transmission indicates that qnrD gene may spread in pet animal veterinary clinic.