本文選題：奶牛乳腺炎 + 耐甲氧西林金黃色葡萄球菌��； 參考：《中國(guó)農(nóng)業(yè)大學(xué)》2016年博士論文

【摘要】：乳腺炎是奶牛養(yǎng)殖業(yè)中造成經(jīng)濟(jì)損失最大的疾病,金黃色葡萄球菌是其主要致病菌之一,在泌乳牛頭混合奶樣中的分離率高達(dá)20-50%。目前,抗生素仍是預(yù)防和治療金黃色葡萄球菌的唯一有效藥物,在適應(yīng)性變異和抗生素的選擇壓力下,各地分離菌株已對(duì)多種抗生素產(chǎn)生耐藥,給臨床治療帶來很大困難。為調(diào)查我國(guó)奶牛隱性乳腺炎中金黃色葡萄球菌的耐藥現(xiàn)狀和耐藥基因分布,明確其分子流行病學(xué)特點(diǎn),分析牛源MRSA菌株的基因組特征。采集2010-2013年間北京、山西、山東、內(nèi)蒙古、浙江和新疆六省區(qū)的2103份奶樣,從確診的1069份隱性乳腺炎樣本中分離鑒定出219株金黃色葡萄球菌,采用紙片擴(kuò)散法測(cè)試分離菌株對(duì)獸醫(yī)臨床常用10種藥物的敏感性,并使用多重PCR方法對(duì)其中81株菌進(jìn)行三類六種耐藥基因檢測(cè),結(jié)果顯示,六省區(qū)樣本中70%以上的分離株對(duì)紅霉素、克林霉素、青霉素、復(fù)方新諾明、多西環(huán)素和四環(huán)素耐藥,并且60%的菌株對(duì)5種以上抗生素多重耐藥,但各省區(qū)分離株對(duì)不同藥物的敏感性存在差異；耐藥基因調(diào)查顯示,被檢測(cè)的90%以上的分離株攜帶耐藥基因,ermC, aac(6')/aph(2")、aph(3')-Ⅲ、tetK和tetM耐藥基因是主要流行基因；此外,從中鑒定出mecA陰性耐甲氧西林菌株。進(jìn)一步,使用MLST分型方法對(duì)已完成耐藥基因檢測(cè)的菌株進(jìn)行分子分型,并對(duì)鑒定的MRSA菌株進(jìn)行SCCmec分型,結(jié)果表明該區(qū)域分離株的流行序列型為ST97和ST398,屬于CC5和CC398克隆復(fù)合群;6株MRSA菌株屬于CC5,其中3株為ST97-SCCmec Ⅳ,其它為ST965-SCCmec Ⅳ、 ST6-SCCmec Ⅳ和ST9-SCCmec NT;同時(shí),使用eBURST v3軟件分析MLST數(shù)據(jù)庫(kù)中醫(yī)源和牛源MRSA相關(guān)性,分析表明醫(yī)源和牛源MRSA形成是相對(duì)獨(dú)立的,已報(bào)道的牛源MRSA為MSSA菌株獲得SCCmec而產(chǎn)生的,未大范圍擴(kuò)散。此外,基于Hiseq 2000和PacBio SMRT技術(shù)的測(cè)序數(shù)據(jù),使用de novo拼接方法獲得多重耐藥MRSA菌株Z35和Z43的全基因組序列并進(jìn)行SCCmec特征分析,結(jié)果顯示Z35為ST9-SCCmec ⅩⅡ,攜帶重組酶基因復(fù)合體ccrC2; Z43為ST97-SCCmec Ⅳ,該基因組序列與S. aureus Mu50同源性較高,SCCmec Ⅳ結(jié)構(gòu)中存在約15 Kb的J2區(qū),含有多種耐藥基因。本研究表明我國(guó)六省區(qū)奶牛隱性乳腺炎性金黃色葡萄球菌的流行序列型為ST97和ST398,屬于CC5和CC398克隆復(fù)合群；ermC、aac(6')/aph(2")、aph(3')-Ⅲ和tetM耐藥基因是該區(qū)域金黃色葡萄球菌耐藥的主要基因;牛源MRSA是由不同序列型的MSSA獲得SCCmec而產(chǎn)生的,未造成大范圍擴(kuò)散；牛源ST9-MRSA-SCOmec ⅩⅡ和ST97-MRSA-SCCmecⅣ的全基因組測(cè)序顯示其分別攜帶重組酶基因復(fù)合體ccrC2和含有多種耐藥基因的J2區(qū)。
[Abstract]:Mastitis is the most economic loss disease in dairy cattle breeding, Staphylococcus aureus is one of the main pathogenic bacteria, the isolation rate is as high as 20-50 in mixed milk samples of lactating cattle. At present, antibiotics are still the only effective drugs for the prevention and treatment of Staphylococcus aureus. Under the adaptive variation and the pressure of antibiotic selection, the strains isolated from various places have become resistant to many kinds of antibiotics, which brings great difficulties to clinical treatment. In order to investigate the present situation of drug resistance and gene distribution of Staphylococcus aureus in cow recessive mastitis in China, the molecular epidemiological characteristics of Staphylococcus aureus and the genomic characteristics of bovine MRSA strain were analyzed. From 2010 to 2013, 2103 milk samples were collected from Beijing, Shanxi, Shandong, Inner Mongolia, Zhejiang and Xinjiang provinces, and 219 strains of Staphylococcus aureus were isolated from 1069 confirmed occult mastitis samples. The susceptibility of the isolated strains to 10 kinds of drugs commonly used in veterinary clinic was tested by disk diffusion method, and the multiplex PCR method was used to detect the three types and six drug resistance genes of 81 strains. The results showed that, More than 70% of the isolates in the six provinces were resistant to erythromycin, clindamycin, penicillin, compound sulfamine, doxycycline and tetracycline, and 60% of the isolates were multidrug resistant to more than 5 antibiotics. However, the susceptibility of the isolates to different drugs was different in different provinces, and the drug-resistance gene survey showed that more than 90% of the isolates were carrying the drug resistance gene, aac(6')/aph(2 "Hapaphora 3tetK and tetM resistance genes" were the main prevalent genes, in addition, more than 90% of the isolates carried the drug resistance gene, and the drug resistance genes were found to be the main prevalent genes. MecA negative methicillin-resistant strains were identified. Furthermore, MLST typing method was used to type the strains that had completed the detection of drug resistance genes, and SCCmec genotyping was used to identify MRSA strains. The results showed that the epidemic sequence types of the isolates were ST97 and ST398.The MRSA strains belonging to CC5 and CC398 clone complex belonged to CC5, three of them were ST97-SCCmec 鈪，

本文編號(hào)：2008734