番鸭源鸭疫里默氏杆菌的耐药性及rpoB基因突变分析

Drug Resistance and rpoB Gene Mutation of Riemerella anatipestifer Isolated from Diseased Muscovy Ducks

【目的】了解福建省莆田市番鸭源鸭疫里默氏杆菌的耐药性及rpoB基因突变情况。【方法】无菌采集病死番鸭的脑、心脏、肝脏进行细菌分离纯化,提取分离株基因组DNA,利用16S rDNA基因特异性引物进行PCR鉴定,纸片法进行药敏试验,扩增并分析rpoB基因利福平耐药决定区序列。【结果】共分离到49株鸭疫里默氏杆菌,这些菌株均表现广谱耐药性,耐药谱介于11~21种药物,分离株对氨基糖苷类、大环内酯类、复方新诺明、多黏菌素B和利福平等药物的耐药性高,对四环素类、β-内酰胺类和氟苯尼考等药物的敏感性高。44株利福平耐药菌的rpoB基因出现R494K(43/44)单点突变和R494K和V382I(1/44)的双点突变,R494K单点突变也在1株利福平敏感菌中发现。【结论】近期防治鸭传染性浆膜炎可首选四环素类、β-内酰胺类和氟苯尼考等药物,利福平耐药决定区氨基酸的R494K单点突变可能是鸭疫里默氏杆菌对利福平耐药的主要机制之一。

【Objective】Drug resistance and rpoB gene mutation of Riemerella anatipestifer isolated from diseased Muscovy ducks in Putian,Fujian were studied.【Method】Brain,heart,and liver tissues were aseptically collected from the dead Muscovy ducks that were infected by the disease for isolation,identification,and drug resistance of the pathogen.The genomic DNA of the isolated strains were extracted and the 16S rDNA gene specific primers used for PCR identification.The disk method was applied to test the drug sensitivity of the isolates.The rifampicin resisting region in the rpoB gene was amplified and analyzed.【Result】Forty-nine strains of R.anatipestifer were isolated to show a broad-spectrum resistance to 11 to 21 kinds of drug,such as,aminoglycosides,macrolides,compound sulfamethoxazole,polymyxin B and rifampicin.But they were highly sensitive to tetracyclines,β-lactams,and florfenicol.In the rpoB gene of 44 rifampicin-resistant strains,a single point mutation,R494K(43/44),and two double point mutations,R494K and V382I(1/44),were found.R494K also existed in one rifampicin sensitive strain.【Conclusion】It appeared that tetracyclines,β-Lactams,and florfenicol could be the first choice for preventing and treating duck infectious serositis.The single point amino acid mutation location of R494K in the region that determines the rifampicin-resistance could harbor the key to unlocking the mechanisms of the drug resistance of R.anatipestifer.