成都地区肉鸭屠宰链弯曲菌毒力基因分布及分子分型研究

目的 了解并分析肉鸭屠宰环节中弯曲菌分离株的9种毒力基因分布及分子分型特征。方法 利用特异性引物对弯曲菌9种与致病力相关的毒力基因进行PCR检测;参照美国PulseNet 脉冲场凝胶电泳(PFGE)标准方法,对68株鸭源弯曲菌分离株进行PFGE分型。结果 毒力基因PCR检测结果显示空肠弯曲菌中cadF、iamA和cheY毒力基因携带率均为100%,flaA(97.1%)、cdtB(94.3%)、cdtC(94.3%)和ciaB(80%)毒力基因的携带率也较高,其余毒力基因cdtA(25.7%),virB11(2.9%)较低;结肠弯曲菌中除cadF(100%)毒力基因外,高于50%携带率的毒力基因有cheY(84.8%)、cdtB(72.7%)、iamA(66.7%)和cdtA(54.5%),另外4个毒力基因flaA(48.5%)、virB11(18.2%)、cdtC(36.4%)和ciaB(18.2%)携带率均较低。利用PFGE方法对弯曲菌分离株进行分子分型,结果显示35株空肠弯曲菌和33株结肠弯曲菌可分为15个和11个谱型,表现为较低的遗传多样性。结论 弯曲菌毒力基因分布广泛,且空肠弯曲菌携带率较高;PFGE基因谱型相似性表明该肉鸭屠宰场存在交叉感染和弯曲菌沿屠宰链传播的现象。

Virulence gene distribution and molecular typing of Campylobacter isolates from duck- slaughter chain in Chengdu,China

To understand the virulence gene distribution and molecular typing characteristics of Campylobacter isolates from duck slaughter chain, a total of 9 virulence-associated genes of Campylobacter spp. were investigated by PCR to assess the potential risk to human. In addition, 68 isolates of Campylobacter were subjected to genotype analysis using pulsed-field gel electrophoresis (PFGE) according to the method of PulseNet. The results indicated that the most commonly observed virulence genes were cadF (100%), iamA (100%) and cheY (100%) in 35 strains of Campylobacter jejuni, followed by flaA (97.1%), cdtB (94.3%), cdtC (94.3%) and ciaB (80%). The occurrence of virulence genes of cdtA (25.7%) and virB11 (2.9%) were lowe. As for Campylobacter coli, the virulence gene of cadF (100%) was observed in all the 33 isolates, followed by cheY (84.8%), cdtB (72.7%), iamA (66.7%) and cdtA (54.5%). The virulence genes of flaA (48.5%), virB11 (18.2%), cdtC (36.4%) and ciaB (18.2%) had low carrying rates. In the PFGE molecular typing, the band similarity coefficient greater than 85% was regarded as the identical genotype. The PFGE results showed that 35 strains of Campylobacter jejuni and 33 strains of Campylobacter coli could be divided into 15 and 11 patterns, which were characterized by lower genetic diversity. The analysis of the genotypes of Campylobacter isolates indicated that there was a cross contamination and transmission along the slaughter chain in the duck slaughterhouse. The virulence gene of Campylobacter is widely existed, and the carrying rate of Campylobacter jejuni is high. The similarity of PFGE gene profile indicated that there is cross infection and campylobacter transmission along the slaughter chain.