奶牛乳房炎是一種主要由病原微生物引起的奶牛疾病,在世界各地都有發(fā)生。感染后奶牛奶產(chǎn)量的下降,甚至是慢性感染牛的淘汰,都給奶牛養(yǎng)殖業(yè)造成巨大的經(jīng)濟(jì)損失。病原微生物能穿透乳頭管,并在泌乳腔中繁殖,進(jìn)而引起乳房炎。多數(shù)乳房炎病例是由一個相對小群體的細(xì)菌造成的,包括金黃色葡萄球菌,乳房鏈球菌,大腸桿菌和隱秘化膿桿菌等。奶牛乳房炎指的是乳腺的炎癥,炎癥嚴(yán)重程度取決于病原體和宿主反應(yīng)。這些病原微生物會發(fā)生進(jìn)化,并通過許多戰(zhàn)略抵制抗生素的作用和得以生存。小菌落突變株和生物膜的形成,以及介導(dǎo)滅活酶的基因表達(dá),都是細(xì)菌逃避抗生素作用的生存策略。進(jìn)化后的細(xì)菌常常能引起持續(xù)感染的奶牛乳房炎。在本研究中,我們從臨床與亞臨床型奶牛乳房炎（第二章與第三章）,慢性與復(fù)發(fā)性奶牛乳房炎（第四章）分離出金黃色葡萄球菌和隱秘化膿棒狀桿菌,并對其毒力因子,生物膜的形成,小菌落突變體（small colony variants,SCVs）的形成,耐藥基因,以及耐藥特征進(jìn)行了檢測與分析。研究一：本文著重研究35株在兩個奶牛場內(nèi)分離到的金黃色葡萄球菌的流行情況,測定金黃色葡萄球菌的耐藥性,尤其是青霉素和甲氧西林,并研究金黃色葡萄球... 

【文章頁數(shù)】：140 頁

【學(xué)位級別】：博士

【文章目錄】：
中文摘要
Abstract
ABBREVIATIONS
Chapter 1 REVIEW OF THE LITERATURE
    1.1 MASTITIS
        1.1.1 Description
        1.1.2 The Mammary Gland
        1.1.3 Mammary Epithelial Cells(MEC)
    1.2 Mastitis Pathogens
        1.2.1 Staphylococcus aureus
        1.2.2 Trueperella (Arcanobacterium) pyogenes
    1.3 Bacterial survival strategies
        1.3.1 Antibiotic resistance
        1.3.2 Forming biofilm (slime)
        1.3.3 Forming small colony variants (SCVs)
        1.3.4 Searching for novel antibiotics targets
    1.4 Objective and meaning of the studies described in this Ihesis
Chapter 2:Properties of Staphylococcus aureus Isolated from Mastitis at twoDairy Herds in China
    2.1 Molecular methods for PCR-mediated identification
        2.1.1 16S rRNA gene
        2.1.2 Random amplified polymorphic DNA (RAPD)
    2.2 The role of bacterial virulence factors in Staphylococcus aureus intramammaryinfection
        2.2.1 Control and expression of virulence factors
        2.2.2 Virulence factors involved in establishing an infection
        2.2.3 Virulence factors involved in maintenance of infection
    2.3 Staphylococcal biofilm formation
        2.3.1 Molecules responsible for exopolysaccharide production
        2.3.2 PIA production and the intracellular adhesion locus
    2.4 Antimicrobial resistance of bovine Staphylococcus aureus
    2.5 Materials and methods
        2.5.1 Origin of S. aureus isolates
        2.5.2 Study animals and herds
        2.5.3 Clinical examination of the cows and mastitis follow-up
        2.5.4 Sample collection
        2.5.5 Bacterial isolation and conventional identification
        2.5.6 Biofilm formation
        2.5.7 DNA extraction and preparation
        2.5.8 Detection of genes encoding virulence and adhesion factors using PCR
        2.5.9 Detection of ica locus by PCR
        2.5.10 Antimicrobial susceptibility testing
    2.6 Results
        2.6.1 Bacterial isolation and conventional identification
        2.6.2 Random amplified polymorphic DNA (RAPD)
        2.6.3 Biofilm formation
        2.6.4 S.aureus virulence gene profiles
        2.6.5 Detection of ica locus by PCR
        2.6.6 Antimicrobial resistance of S.aureus
    2.7 Discussion
    2.8 Conclusion
Chapter3:Characteristics of Trueperella pyogenes isolated from bovinemastitis
    3.1 Putative virulence factors of A.(T.) pyogenes
        3.1.1 Pyolysin
        3.1.2 Collagen-binding proteins
        3.1.3. Exoenzymes
        3.1.4 Fimbriae
        3.1.5 Hemolytic properties and CAMP-like hemolytic reactions
    3.2 Materials and methods
        3.2.1 Isolation and identification of T. pyogenes from milk samples
        3.2.2 Identification and further characterization of the bacteria by conventional methods
        3.2.3 Biochemical tests
        3.2.4 Growth curve
        3.2.5 Growth on Loeffler medium
        3.2.6 Identification and molecular characterization of the bacteria by PCR
        3.2.7 Detection of potential virulence factor and antibiotic resistance genes
        3.2.8 Biofilm production
        3.2.9 Antibiotic resistance
        3.2.10 Intracellular assessment of T. pyogenes
        3.2.11 Preservation of the bacteria
    3.3 Results
        3.3.1 Isolation and identification of T. pyogenes from milk
        3.3.2 Biochemical properties and CAMP-like hemolytic reactions
        3.3.3 Growth curve
        3.3.4 Analysis of DNA amplification products obtained by RAPD
        3.3.5 Biofilm production
        3.3.6 Antibiotic resistance
        3.3.7 Intracellular assessment of T. pyogenes
        3.3.8 Genes encoding potential virulence factors
    3.4 Discussion
    3.5 Conclusion
CHAPTER 4:Characteristics of Staphylococcus aureus and Trueperellapyogenes-Small Colony Variants and their Parent Strains Isolated fromChronic Mastitis
    4.1 Characteristics of Staphylococcus aureus Small Colony Variant and Its Parent Strain Isolated from Chronic Mastitis
        4.1.1 Project aims
        4.1.2 Materials and methods
        4.1.3 Results
        4.1.4 Discussion
        4.1.5 Conclusion
    4.2 Isolation and characterization of novel Trueperella pyogenes small colony variants from bovine mastitis cases
        4.2.1 Project aims
        4.2.2 Materials and methods
        4.2.3 Results
        4.2.4 Discussion
        4.2.5 Conclusion
Chapter 5:Conclusions
References
Acknowledgement
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