内蒙古地区奶牛乳房炎葡萄球菌和链球菌流行病学调查及耐药性分析

发布时间：2018-06-15 13:00

本文选题：奶牛乳房炎 + 葡萄球菌　；参考：《吉林农业大学》2017年硕士论文

【摘要】：奶牛乳房炎是奶牛最常发生的疾病之一,给养殖业带来了巨大的经济损失,而病原菌感染是奶牛乳房炎最主要的病因。为了了解内蒙古不同地区引起奶牛乳房炎的主要病原菌及其耐药性情况,本研究对内蒙古不同地区三个规模化奶牛场采集的330份样本进行了葡萄球菌和链球菌的分离培养和鉴定,共得到174株葡萄球菌和24株链球菌,分离率为52.73%(174/330),7.27%(24/330)。以产色、金黄色葡萄球菌和无乳、停乳及乳房链球菌为研究对象,采用脉冲场凝胶电泳技术(PFGE)分析2种葡萄球菌和3种链球菌菌株的亲缘性,从51株葡萄球菌中获得34株不同克隆谱型的葡萄球菌(包括18株金黄色葡萄球菌,16株产色葡萄球菌),从24株链球菌中获得16株不同谱型的的链球菌(10株无乳链球菌,3株停乳链球菌及3株乳房链球菌),并对其中8株金黄色葡萄球菌进行多位点序列(MLST)分型,其分型结果与PFGE分型结果一致。本研究选取12种抗生素对40株PFGE谱型不同的优势代表株进行药敏实验,检测菌株的耐药表型及相关耐药基因。结果显示:金黄色葡萄球菌对林可霉素(50%)、青霉素(62.5%)、苯唑西林(50%)耐药率≥50%,而对万古霉素、泰妙菌素、沃尼妙林及氟苯尼考4种抗生素全部敏感;产色葡萄球菌对林可霉素(75%)和青霉素(68.75%)耐药严重,而对头孢噻呋、环丙沙星、万古霉素、泰妙菌素、沃尼妙林、氟苯尼考6种抗生素均敏感;16株链球菌对林可霉素和红霉素耐药率60%,对四环素耐药率也较高(50%),但对β-内酰胺类药物耐药率相对较低,耐药率为6%-19%。其中青霉素18.75%,而头孢噻呋仅6.25%。而介导β-内酰胺类抗生素相关耐药基因主要为bla Z基因,介导林可霉素类抗生素相关耐药基因主要为lnu(A)和lnu(B)基因,介导大环内酯类抗生素耐药基因主要为erm(B),介导四环素类抗生素相关耐药基因主要为tet(M),tet(O),tet(L)。3株乳房链球菌存在介导多重耐药lsa(E)基因,且均位于染色体上,可在菌间进行垂直传播。本研究为内蒙古地区由葡萄球菌和链球菌引发的奶牛乳房炎的诊断提供依据,也能为疾病的预防和控制提供必要的理论基础。
[Abstract]:Cow mastitis is one of the most common diseases in dairy cows, which brings huge economic losses to the breeding industry, and the pathogen infection is the main cause of dairy cow mastitis. In order to understand the main pathogens and drug resistance of dairy cow mastitis in different areas of Inner Mongolia, In this study, a total of 174 staphylococci and 24 streptococcus strains were isolated and identified from 330 samples collected from three large-scale dairy farms in different areas of Inner Mongolia. Two strains of Staphylococcus aureus (Staphylococcus aureus) and three strains of Streptococcus brevis (Streptococcus brevis) were analyzed by pulsed field gel electrophoresis (PFGE). 34 strains of Staphylococcus (including 18 strains of Staphylococcus aureus, 16 strains of Staphylococcus chromogenin) and 16 strains of Streptococcus spp (from 24 strains of Streptococcus spp.) were obtained from 51 strains of Staphylococcus. 10 strains of Streptococcus spp without lactobacillus were obtained. Three strains of Streptococcus brevis and three strains of Streptococcus brevis were isolated from Staphylococcus aureus, and 8 strains of Staphylococcus aureus were classified by multilocus sequence analysis (MLST). The results of classification were consistent with those of PFGE. In this study, a total of 12 antibiotics were selected to test the susceptibility of 40 representative strains with different PFGE patterns to identify the phenotypes of drug resistance and related drug resistance genes. The results showed that the resistance rate of Staphylococcus aureus to lincomycin 50, penicillin 62.5 and oxacillin 50 was more than 50, but sensitive to vancomycin, tymitin, Vannimarin and florfenicol. Staphylococcus chromogens is highly resistant to lincomycin (75) and penicillin (68.75), and to cefotioxime, ciprofloxacin, vancomycin, tymycin, and Vannimarin, and to cefuroxime, ciprofloxacin, vancomycin, and vanimicin. Sixteen strains of streptococcus were sensitive to lincomycin and erythromycin, and 50% to tetracycline, but the resistance rate to 尾 -lactam was relatively low. Penicillin 18.75 and ceftiofuroxime only 6.25. However, bla Z gene is the main gene that mediates 尾 -lactam antibiotic related resistance, and Lnuan gene and Lnun B gene are the main genes that mediate lincomycin antibiotic related drug resistance. The major genes that mediate the resistance of macrolide antibiotics are ermmbium and tetracycline antibiotics related resistance genes mainly exist in Streptococcus mastifolia. 3 strains of Streptococcus brevis, which are located on chromosomes and can be transmitted vertically between bacteria. This study provides a basis for the diagnosis of cow mastitis caused by staphylococcus and streptococcus in Inner Mongolia, and also provides the necessary theoretical basis for disease prevention and control.
【学位授予单位】：吉林农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S858.23

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