养鸡场空气中抗性基因和条件致病菌污染特征

集约化养殖场被认为是空气环境中抗性基因和致病菌的重要来源.本研究采集了养鸡场粪便和舍内外空气样本,对其抗生素抗性基因和条件致病菌的种类进行分析,包括五类抗生素(β-内酰胺类的23个基因、四环素23个基因、喹诺酮5个基因、磺胺类5个基因和红霉素2个基因)抗性基因、5种条件致病菌(肠球菌属、大肠杆菌属、葡萄球菌属、弯曲杆菌属和产气荚膜梭状芽胞杆菌属各1个基因)以及一类整合子(int I1)特异基因;并利用荧光定量PCR对检出率较高的典型基因浓度进行检测.结果显示,空气中5类抗生素抗性基因分别检出8、7、2、3和2个,同时检测到两种致病菌.目标基因在舍内空气中的检出率小于等于粪便样本.蛋鸡和肉鸡舍内空气中总细菌基因(16S r DNA)浓度为106copies·m-3,其他典型基因浓度约104copies·m-3,且在舍外的浓度要远低于舍内.抗生素抗性基因和条件致病菌基因在空气中所占比例高于粪便,舍内高于舍外.初步研究结果表明,粪便可能是舍内抗生素抗性基因、条件致病基因以及一类整合子的重要来源.本研究结果将为集约化养殖场抗生素抗性基因和致病菌的来源分析,以及养殖场对周边空气环境污染的风险评估提供基础数据.

Sources and Pollution Characteristics of Antibiotic Resistance Genes and Conditional Pathogenic Bacteria in Concentrated Poultry Feeding Operations

Concentrated animal feeding operations (CAFOs) is considered a source of airborne human pathogens and antibiotic resistance genes. This study collected fecal samples and corresponding air samples from inside and outside atmospheric environments of layer and broiler feeding operations. We detected the types of 61 genes including five classes of antibiotics antibiotic resistance genes (23 genes of ampicillin, 23 genes of tetracycline, 5 genes of quinolones, 5 genes of sulfonamides and 2 genes of erythromycin), five conditional pathogenic bacteria (Enterococcus, Escherichia coli, Staphylococcus, Campylobacter and Clostridium perfringens) and class1 integron. Quantitative real time PCR was used to analyze concentrations of typical genes with relatively high detection rates. The results indicated that the detection rates of antibiotic resistance genes were 8,7,2,3 and 2. At the same time, two kinds of pathogenic bacteria were detected. The detection rates of the target genes in the air were lower than those of the fecal sample. The total bacterial gene (16S rDNA) concentration in the air of layer and broiler was 10⁶ copies·m^-3, and that of the other typical genes was about 10⁴copies·m^-3. And the outdoor concentration was much lower than the indoor concentration. The proportions of antibiotic resistance genes and conditional pathogenic bacteria in the air were higher than those in the fecal samples and the outdoor proportions were lower than the indoor proportions. Preliminary results of this study indicated that feces was an important source of antibiotic resistance genes, conditional pathogenic bacteria and class1 integron. Aerosolization degrees of genes in feces were different. This study will provide the basic data for both source tracking of antibiotic resistance genes and pathogens from CAFOs and risk assessment of pollution of CAFOs in the surrounding air environment.