奶牛乳房炎防治技术研究分析

奶牛乳房炎是奶牛的常见病之一,更是影响其养殖业发展、奶产品质量的重要原因。因此在奶牛的养殖中一定要从各个环境入手加强对奶牛乳房炎的防治。本文分析了奶牛乳房炎的发生原因及预防方法,为提升生产技术,保证奶产品的质量提供参考。     

泰州市奶牛乳房炎调查及其病原菌的分离

奶牛乳房炎是奶牛场的常发病和难以防治的疾病,为进一步了解引起奶牛乳房炎的病原微生物,本研究通过对泰州市3个奶牛场572头泌乳牛的乳房炎发病率进行了调查并对乳房炎主要病原菌进行分离和鉴定。结果表明,奶牛临床型乳房炎的发病率为7.69%,隐性型乳房炎发病率为56.64%,乳区阳性率为33.8%,其中临床型:隐性=1:7.36。从65份确定患有乳房炎的奶样中共分离获得8种细菌、156株分离株,且引起乳房炎的主要病原菌是金黄色葡萄球菌和表皮葡萄球菌,其次是停乳链球菌、大肠杆菌、乳房链球菌和无乳链球菌,其检出率分别为42.31%、23.08%、8.97%、6.41%、5.13%和1.28%。该项调查结果初步明确了泰州市乳房炎发病情况,同时为进一步综合防治奶牛乳房炎和研制乳房炎治疗药物提供了科学依据。     

奶牛乳房炎抗性候选基因的研究进展

乳房炎是奶业生产中的一种常见病,发病率很高,每年给世界各国奶牛饲养者造成严重的经济损失。乳房炎的影响因素很多,但遗传因素对其起着重要作用。综述了乳铁蛋白基因、MHC/BoLA基因、ToLL样受体家族基因、趋化性细胞因子受体基因、牛锌指蛋白313基因、β-防御素基因和热休克蛋白70基因等奶牛乳房炎抗性候选基因的研究现状。     

致病性金黄色葡萄球菌新疗法

科学网消息：由台湾中研院生物化学研究所特聘研究员兼副院长王惠钧所领导的研究团队与美国研究室携手合作,共同研究造成严重感染的金黄色葡萄球菌可能的崭新治疗方法。此篇研究论文于2月14日发表于《科学》（Science）上。目前众所皆知的甲氧苯青霉素抗药性金黄葡萄球菌MRSA（methicillin—resistant Staphylococcus aureus）已普遍散播在社区与医院环境中,伺机引起机缘性感染。     

临沂市奶牛乳房炎病原菌的分离鉴定与药敏试验

目的为弄清临沂市奶牛乳房炎主要病原菌种类及其药物敏感情况,为科学防治本病提供依据。方法采集患乳房炎奶牛的乳样进行细菌分离鉴定,并对主要病原菌做药敏试验。结果从115份乳样中,分离出6种127株病原菌,其中金黄色葡萄球菌46株,占36.22%,无乳链球菌33株,占25.98%,停乳链球菌21株,占16.53%,大肠埃希菌17株,占13.39%,乳房链球菌8株,占6.3%,沙门菌2株,占1.57%;主要病原菌均对头孢喹诺和左氧氟沙星高度敏感。结论临沂市奶牛乳房炎主要致病菌为金黄色葡萄球菌、链球菌和大肠埃希菌。首选药物为头孢喹诺和左氧氟沙星。因此,治疗奶牛乳房炎应通过药敏试验,合理地选择药物。     

金黄色葡萄球菌荚膜多糖研究进展

金黄色葡萄球菌作为引起人和动物发病的一种主要的致病菌,已严重影响到人们的身体健康和畜牧业的发展。致病性金黄色葡萄球菌多数含有荚膜成分,并且这种荚膜成分与金黄色葡萄球菌的毒力和抗噬菌作用有关。主要从金黄色葡萄球菌荚膜多糖的5型和8型血清学分类、分子结构、影响因素、表达调控等方面简要介绍了目前国内外关于金黄色葡萄球菌荚膜多糖的研究进展。     

金黄色葡萄球菌耐药性变迁

为了解 1 999～ 2 0 0 3年临床分离金黄色葡萄球菌耐药性的变迁情况 ,采用K B方法和微量肉汤稀释法 ,对 1 999年 1月至 2 0 0 3年 1 2月临床分离的 42 3株金黄色葡萄球菌进行药敏试验 ;耐药率的显著性比较采用x2 检验。结果显示 ,1 999～ 2 0 0 3年从临床送检标本中共分离出金黄色葡萄球菌 42 3株。 2 0 0 2～ 2 0 0 3年MRSA的分离率为 1 9.7% (2 9/ 1 47)有增加趋势 ,高于 1 999～ 2 0 0 0年度分离率 1 7.5 % (3 3 / 1 89)。在 2 0 0 2～2 0 0 3年间MSSA对头孢吡肟、环丙沙星、左旋氧氟沙星、复方新诺明、氯霉素和庆大霉素的耐药率分别为0 .0 % ,4.6% ,2 .3 % ,1 .3 % ,6.8%和 2 1 .8%。而对青霉素、红霉素和克林霉素耐药率较高 ,为 5 1 .9% ,70 .4%和 41 .3 %。与 1 999～ 2 0 0 0年比较 ,MSSA对青霉素G、环丙沙星、四环素和复方新诺明的耐药率明显下降 ,p <0 .0 5。 5a间未发现耐万古霉素和替考拉宁菌株。 1 999～ 2 0 0 3年MRSA发生率有增加趋势。耐药性监测有助于遏制抗菌药物的耐药问题。     

新型奶牛乳房炎多联苗的研制及免疫力试验

目的：筛选出毒力较强的金黄色葡萄球菌、大肠杆菌、无乳链球菌作为制苗菌株,制成多联菌苗,预防及治疗奶牛乳房炎。方法：通过菌株的分离、纯化、鉴定试验及毒力试验获得毒力较强的菌株,制成金黄色葡萄球菌类毒素及菌体蛋白、大肠杆菌和无乳链球菌灭活菌苗,合理配伍制成多联菌苗,进行安全、异常毒性及免疫力试验。结果：所选金黄色葡萄球菌、大肠杆菌、无乳链球菌的最小致死量分别是3．0&#215;10^8／ml、1．5&#215;10^8／ml、9．0&#215;10^8／ml,多联苗安全、异常毒性试验合格,对免疫组小白鼠保护率为83．3％。结论：该多联菌苗具有安全、无毒、高效的特点,可以用来预防及治疗奶牛乳房炎。     

PCR扩增血浆凝固酶基因检测致病性金黄色葡萄球菌

金黄色葡萄球菌致病株能同时产生两种蛋白质,一种分泌于菌体外,另一种结合在菌体表面,它们能使含有抗凝剂的家兔或人的血浆凝固,称为凝固酶（Coagulase）。凝固酶是检验致病性金黄色葡萄球菌的重要指标。试验根据GenBank公布的血浆凝固酶序列,设计特异PCR引物,利用聚合酶链式反应扩增出金黄色葡萄球菌凝固酶基因,克隆测序,与Genbank中已公布的序列同源性达到100％,并且检测结果与用兔血浆进行血浆凝固酶实验结果完全吻合,建立了金黄色葡萄球菌性乳腺炎的快速诊断方法。     

金黄色葡萄球菌的流行病学分型

金黄色葡萄球菌引起的医院获得性感染问题至今仍备受国内外有关部门重视。控制感染的一个重要策略就是弄清传染源及传播途径，中断菌株在敏感病人之间或无症状携带者与病人之间的传播，这样的流行病学研究依赖于有高鉴别力的分型系统来辨别菌株的相关性。本文就金葡菌传统的基于表型的噬菌体分型、血清学分型、耐药谱分型、凝固酶分型以及新兴的质粒分型、染色体ＤＮＡ脉冲电泳分型、核糖分型和全细胞蛋白图谱分型等分子生物学分型方法作一综述。     

Evaluation of six commercial identification kits for the identification of Staphylococcus aureus isolated from bovine mastitis

AIMS: Comparison of six commercially available in human medicine well-established slide agglutination systems for the identification of Staphylococcus aureus. METHODS AND RESULTS: Slide agglutination tests were compared with the conventional tube coagulase test, biochemical identification and with the molecular identification by polymerase chain reaction (PCR) amplification of species-specific parts of the gene encoding the 23S RNA. Systems evaluated included Masta-Staph (Mast Diagnostics), Staphylase-Test (Oxoid), Staphytect-Plus (Oxoid), Staphyloslide Latex (Becton Dickinson), Slidex Staph Plus (bioMerieux) and Dry Spot Staphytect Plus (Oxoid). A total of 141 staphylococcal strains isolated from cases of bovine mastitis including 90 S. aureus, 14 Staphylococcus epidermidis, 10 Staphylococcus warneri, 13 Staphylococcus xylosus, 11 Staphylococcus haemolyticus and three other coagulase-negative staphylococci were tested with each method. Staphylococcus aureus strains were selected by macrorestriction analysis with pulsed field gel electrophoresis (PFGE). Only genetically unrelated strains were included in the study. The sensitivities and specificities of the test were as follows: Masta-Staph 86.7 and 90.1%, Staphylase-Test 78.4 and 85.1%, Staphytect-Plus 81.1 and 86.5%, Staphyloslide Latex 77.8 and 84.4%, Slidex Staph Plus 77.8 and 84.4%, Dry Spot Staphytect Plus 75.6 and 83.0%. CONCLUSIONS: The results of this evaluation suggest that the six slide agglutination methods tested can provide rapid identification of S. aureus also from bovine mastitis. The sensitivity and specificity seems to be less than those reported from human S. aureus isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: This is one of the first comparative reported investigations about the applicability of different commercially available slide agglutination tests for the detection of S. aureus from bovine mastitis using PFGE selected clinical isolates.     

Adhesion of Staphylococcus aureus to Bovine Mammary Epithelial Cells Induced by Growth in Milk Whey

Staphylococcus aureus strains isolated from bovine intramammary infection (mastitis) were tested for adhesion to bovine mammary epithelial cells after growth in milk whey or TSB. Bacteria grown in milk whey adhered more efficiently to mammary gland epithelial cells in vitro than the corresponding homologous bacteria grown in TSB. Trypsin treatment of milk whey-grown S. aureus had no effect on their adherence. Whereas, pretreatment with periodate significantly decreased bacterial adherence capacity. Periodate treatment of TSB-grown bacteria had no effect on adhesion to the mammary gland epithelial cells.     

Zfb株牛源金黄色葡萄球菌生物学特性

从临床患病牛乳样内分离出的金黄色葡萄球菌β-溶血型致病菌株, 命名为zfb, 运用微生物学及现代分子生物学手段检测了该菌株的生物学特性, 以金葡菌ATCC 25923为对照株。结果表明, 金黄色葡萄球菌zfb不产生脂酶, 有抗药性, 在改良型血清软琼脂培养基中观察荚膜形态, 活体内和体外均显现散布型状态。同时, 以昆明小白鼠为动物模型, 测定了半数致死量和器官侵袭力。金黄色葡萄球菌牛源分离株zfb的半数致死率为10-4.33/mL, 参考菌株ATCC 25923菌株的半数致死率为10-2.5/mL。对牛源     

Bovine whey proteins inhibit the interaction of Staphylococcus aureus and bacteriophage K

AIMS: To understand the potential use of bacteriophage K to treat bovine Staphylococcus aureus mastitis, we studied the role of whey proteins in the inhibition of the phage-pathogen interaction in vitro. METHODS AND RESULTS: The interaction of bacteriophage K and S. aureus strain Newbould 305 was studied in raw bovine whey and serum. Incubation of S. aureus with phage in whey showed that the bacteria are more resistant to phage lysis when grown in whey and also bovine serum. Whey collected from 23 animals showed a wide variation in the level of phage-binding inhibition. The role of the protein component of milk whey in this inhibition was established; treatment of the whey by heat, proteases and ultrafiltration removed the inhibitory activity. Brief exposure of S. aureus cells to whey, followed by resuspension in broth, also reduced phage binding. Microscopy showed the adhesion of extracellular material to the S. aureus cell surface following exposure to whey. Chromatographic fractionation of the whey demonstrated that the inhibitory proteins were present in the high molecular weight fraction. CONCLUSIONS: The adsorption of whey proteins to the S. aureus cell surface appeared to inhibit phage attachment and thereby hindered lysis. The inhibitory whey proteins are of high molecular weight in their native form and may sterically block phage attachment sites on the cell surface. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings have implications for any future use of phage therapy in the treatment of mastitis, and other diseases, caused by S. aureus. This pathogen is predicted to be much more resistant to phage treatment in vivo than would be expected from in vitro broth culture experiments.     

Aureocin A70 production is disseminated amongst genetically unrelated Staphylococcus aureus involved in bovine mastitis

Aims: The main aim of this study was to analyse the genetic relationship amongst 46 Staphylococcus aureus Bac⁺ strains isolated in Brazil from 12 geographically distant dairy herds, including 34 isolates that produce the antimicrobial peptide aureocin A70. Methods and Results: The comparison of 46 Staph. aureus Bac⁺ strains was performed by pulsed‐field gel electrophoresis (PFGE). Thirteen different pulsotypes were identified, and the subtype A₁ was the most prevalent one. Nine strains belong to pulsotype F, the second most prevalent and mostly confined to a single herd. The PFGE patterns of the 34 Staph. aureus aureocin A70‐producers, isolated in Brazil, were also compared with those of strains isolated from bovine mastitis cases in Argentina and revealed that these strains are not genetically related. Conclusions: Although a previous study has suggested that a prevalent pulsotype of aureocin A70‐producer Staph. aureus involved in bovine mastitis is disseminated in Argentina, this does not occur in Brazil. Additionally, it was possible to demonstrate that closely related staphylococcal strains can produce distinct staphylococcins. Significance and Impact of the Study: This study corroborates the hypothesis of horizontal gene transfer of aureocin A70 genes amongst distinct staphylococcal strains involved in bovine mastitis, giving them a selective advantage when colonizing the mammary glands.     

In Vivo-Like Antigenic Surface Properties of Staphylococcus aureus from Bovine Mastitis Induced upon Growth in Milk Whey

Antigenic surface properties of Staphylococcus aureus strains grown in milk whey were compared with TSB-grown bacteria using immuno-gold electron microscopy. It is shown that colloidal gold (CG) particles coated with polyclonal antibody raised against Staphylococcus aureus surface antigen expressed in vivo bound to the surface of S. aureus strain F1440 grown in milk whey, but not to homologous bacteria grown in TSB. S. aureus strains grown in milk whey agglutinated in the presence of the polyclonal antibody, whereas the corresponding bacteria grown in TSB did not agglutinate. Immuno-gold particles did not bind to milk whey-grown bacteria treated with periodate. Periodate-treated milk whey-grown bacteria did not agglutinate in the presence of the polyclonal antibody, whereas periodate treatment had no effect on TSB-grown bacteria.     

Diversity of staphylocoagulase and identification of novel variants of staphylocoagulase gene in Staphylococcus aureus

Staphylocoagulase (SC) is a major phenotypic determinant of Staphylococcus aureus. Serotype of SC (coagulase type) is used as an epidemiological marker and 10 types (I-X) have been discriminated so far. To clarify genetic diversity of SC within a single and among different serotype(s), we determined approximately 1500 bp-nucleotide sequences of SC gene encoding D1, D2, and central regions (N-terminal half and central regions of SC; SC(NC)) for a total of 33 S. aureus strains comprising two to three strains from individual coagulase types (I-VIII, X) and 10 strains which were not determined as previously known SC serotypes (ND-strains). Amino acid sequence identities of SC(NC) among strains with a single coagulase type of II, III, IV, V, VI and X were extremely high (more than 99%), whereas lower identity (56-87%) was observed among different types. In contrast, within a single coagulase type of I, VII, or VIII, sequence divergence was found (lowest identity; 82%). SC(NC) sequences from the ND-strains were discriminated into two genetic groups with an identity of 71% to each other (tentatively assigned to genotypes [XI] and [XII]), and exhibited less than 86% sequence identities to those of most known coagulase types. All the types [XI] and [XII] strains were methicillin susceptible and belonged to different sequence types from those of coagulase types I-X strains reported so far by multilocus sequence typing. These findings indicated genetic heterogeneity of SC in coagulase types I, VII, and VIII strains, and the presence of two novel SC genotypes related to antigenicity of SC serotypes.     

Selective growth of Staphylococcus aureus from flushed dairy manure wastewater using acriflavine-supplemented mannitol salt agar

AIMS: To investigate the use of mannitol salt agar (MSA) supplemented with acriflavine for selective growth and quantification of Staphylococcus aureus from flushed dairy manure wastewater (FDMW). METHODS AND RESULTS: Minimal inhibitory concentrations of acriflavine in MSA were determined by comparing the growth of S. aureus subsp. aureus (ATCC 33591) and Staphylococcus epidermidis (ATCC 155) in pure culture. Acriflavine concentrations of 1.3, 1.4 and 1.5 mg l(-1) reduced CFU of S. epidermidis by 43%, 55% and 87%, respectively, while CFU of S. aureus subsp. aureus were only reduced by 15%, 20% and 26% at the respective concentrations of acriflavine. MSA supplemented with 1.5 mg l(-1) acriflavine was tested for selective growth of indigenous S. aureus from three grab samples of FDMW. Acriflavine concentrations of 1.5 mg l(-1) reduced background flora without significantly reducing (P < 0.05) indigenous S. aureus counts. CONCLUSIONS: Acriflavine-supplemented MSA provides an effective media for selective growth and quantification of indigenous S. aureus from FDMW in the presence of high levels of background microflora. SIGNIFICANCE AND IMPACT OF THE STUDY: S. aureus is implicated for mastitis infections in dairy cows. Therefore, a reliable means for monitoring and detecting the organism in FDMW provides a tool for measuring the effectiveness of treatment for reducing S. aureus levels and implementing flushwater recycling without affecting herd health.