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1.
旨在对牛源金黄色葡萄球菌（Staphylococcus aureus，S.aureus）的生物被膜、耐药性、毒素基因和agr基因型进行研究，并分析agr基因型与毒素基因之间的相关性。分别用微量滴定板法、药敏纸片法和PCR对S.aureus的生物被膜、耐药性和毒素基因进行检测，用多重PCR对S.aureus进行agr分型。结果表明，336株牛源S.aureus均能形成生物被膜，其中，形成中等（++）和强（+++）生物被膜的S.aureus分别占52.1%和47.9%。药敏试验结果显示，S.aureus对青霉素耐药最为严重，耐药率达91.7%，其次是红霉素、卡那霉素、克林霉素和庆大霉素，耐药率分别为89.6%、72.9%、66.7%和60.4%，而所有S.aureus对呋喃妥因和利奈唑胺均表现为敏感。PCR检测结果显示，黏附素基因fnbA检出率最高，达99.7%，其次是icaD、icaA、clfA和cna，检出率分别为98.2%、89.6%、86.0%和56.0%，bap基因检出率最低，为14.6%。肠毒素基因sea的检出率为26.5%，其次是seb（8.3%）和sec（6.8%），毒素基因tst的检出率占8.3%。分型结果显示，agr Ⅰ型S.aureus是主要的流行菌株，占77.1%，agr Ⅱ、agr Ⅲ和agr Ⅳ型S.aureus流行率分别为14.0%、4.8%和2.1%。统计分析结果表明，agr Ⅰ型S.aureus更具有携带多种毒素基因的潜力，而agr Ⅳ型S.aureus无毒素基因携带潜力。综上表明，牛乳腺炎性S.aureus对常见的抗菌药物耐药严重，毒素基因分布多样，agr Ⅰ型是奶牛乳腺炎性S.aureus主要的基因型，且具有携带多种毒素基因的能力，其潜在威胁应引起重视。 相似文献
2.
ZHANG Hang LI Xinpu WU Xiaohu DING Xuezhi YAN Zuoting WANG Shengyi LI Hongsheng 《畜牧兽医学报》1956,51(11):2903-2910
The objective of the present study was to investigate the biofilm formation, antimicrobial resistance, virulence genes, and agr genotypes of Staphylococcus aureus (S. aureus) isolated from bovine mastitis cases, and to analyze the correlations between agr genotypes and virulence genes. Biofilm formation, antimicrobial resistance, and virulence genes for 336 strains of S. aureus were detected by microtiter plate method, disk diffusion method, and PCR respectively, and the agr typing of tested strains was determined by multiplex PCR. The results showed that all 336 strains of S. aureus from bovine mastitis were biofilm producers, among which 52.1% and 47.9% of isolates tested were moderate (++) and strong (+++) biofilm producers, respectively. Antimicrobial susceptibility testing demonstrated that S. aureus strains were highly resistant to penicillin, with a resistance rate of 91.7%, followed by erythromycin (89.6%), kanamycin (72.9%), clindamycin (66.7%) and gentamicin (60.4%). However, all isolates were sensitive to nitrofurantoin and linezolid. PCR results showed that the prevalence of fnbA gene was the highest (99.7%), followed by icaD (98.2%), icaA (89.6%), clfA (86.0%), cna (56.0%), and bap (14.6%) genes. Moreover, the sea, seb, sec and tst genes were found in 26.5%, 8.3%, 6.8% and 8.3% of the isolates, respectively. The agr typing results showed that S. aureus strains belonging to agr Ⅰ was predominant in our study, accounting for 77.1% of the isolates, and the frequencies of agr Ⅱ, agr Ⅲ and agr Ⅳ genotypes were 14.0%, 4.8% and 2.1%, respectively. Statistical analysis indicated that the strains of S. aureus belonging to agr Ⅰ genotype have the potential to carry more virulence genes, while no toxin genes could be found in any of the strains belonging to agr Ⅳ. The results revealed high antimicrobial resistance to common antimicrobial agents in S. aureus isolated from bovine mastitis milk samples. Moreover, agr Ⅰ was the predominant genotype with diverse toxin genes in S. aureus from bovine mastitis, and the potential hazard should be of concern. 相似文献
3.
金黄色葡萄球菌是引起奶牛细菌性乳腺炎的主要原因，生物被膜的形成是金黄色葡萄球菌在不利环境条件下持久性存在的关键因素。探索同一株菌在生物被膜态与浮游态生长状态下的耐药性与其生长状态的相关性，可为进一步探究金黄色葡萄球菌的耐药性机制奠定基础。本研究培养了金黄色葡萄球菌的生物被膜，使用光学显微镜和扫描电镜观察其形成过程。测定并比较了9种抗菌药物对32株金黄色葡萄球菌在生物被膜态和浮游态的最小抑菌浓度，并对两种状态下的金黄色葡萄球菌进行转录组学测序，筛选出具有显著性差异的细胞信号通路和表达基因，同时对主要差异表达的基因进行RT-qPCR验证。结果发现，在生物被膜形成前期，随着培养时间的延长，显微镜下观察到的生物被膜态菌聚集面积越来越大，结构也越来越紧密，培养至72 h后，生物被膜逐渐开始分散。MIC测定结果显示浮游态菌的抑菌浓度低于生物被膜态菌。转录组结果显示两种状态菌的差异表达基因共1 512个，其中，生物被膜态菌中上调基因760个，下调752个。GO与KEGG富集分析显示，相比于浮游态菌，生物被膜态菌中与代谢相关的通路显著富集，其次为氨基酸的生物合成和ABC转运蛋白通路。与生物被膜形成相关的基因，如编码ABC转运蛋白的基因表达上调，而与代谢途径相关的基因下调。RT-qPCR验证了10个主要差异基因，其表达差异趋势与转录组测序结果一致。这些差异可能对金黄色葡萄球菌生物被膜态的高耐药性和细菌毒力的研究有所帮助。 相似文献
4.
Kenneth L. Buelow William J. Goodger Michael T. Collins Murray K. Clayton Kenneth V. Nordlund Chester B. Thomas 《Preventive veterinary medicine》1996,25(3-4):343-355
A model was developed to evaluate the effects that methods of obtaining milk samples and culture inoculum volumes had on the sensitivity of microbiological culture to detect Staphylococcus aureus intramammary infections (IMI). An assumption was made that milk from mammary quarters infected with S. aureus only contains bacteria intermittently. A modified sine wave function was used to model this intermittent shedding pattern. Specifications for the components of the shedding cycle used in this function were based on quantitative culture results from 54 experimentally infected S. aureus quarters, sampled daily for a period of 30–49 days. The components of the shedding cycle were length in days, peak number of CFU shed per milliliter of milk, and length of time in the cycle when no shedding occurred. These components were used to estimate the model's predicted distribution of S. aureus CFU ml−1 milk when individual quarter milk samples were cultured for S. aureus. The sensitivity of culture for several sampling methods was then calculated. The model predicted that culture of a single quarter milk sample had a sensitivity ranging from 60 to 87% for detection of S. aureus IMI depending on inoculum volume. Quarter milk samples taken on day 1 and repeated either on day 3 or day 4, and cultured separately using 0.1 ml of milk for culture inoculum, were predicted to have sensitivities of 90–95% and 94–99%, respectively. Other milk-sampling strategies examined included culture of a composite milk sample (equal-volume mixture of milk from four separate mammary quarters ) and pooled milk samples in which samples from different milkings (either quarter or composite samples) were mixed together and then cultured. The range of predicted sensitivities of these other sampling strategies was 30–97%. Factors having the greatest impact on the sensitivity of culture, in order of importance were: the type of milk sample, the volume of milk cultured, and the time interval between repeated milk sample collection strategies. 相似文献
5.
A study was conducted on 207 lactating camels in six herds in Kenya to evaluate the California mastitis test (CMT) for the detection of intramammary infections (IMIs) caused by Streptococcus agalactiae and Staphylococcus aureus and to investigate the prevalence of both the pathogens in the camel udder. IMI with S. agalactiae was found in 12% of all camels sampled. IMI with S. aureus was present in 11% of all camels sampled. The herd-level prevalence of IMI varied between 0 and 50% for S. agalactiae and between 0 and 13% for S. aureus. Longitudinal observations over 10–12 months confirmed persistent infections for both pathogens. Observations in one herd suggested that camel pox was a contributing factor in spreading and exacerbating S. agalactiae udder infections.
The CMT had quarter-level sensitivities of 77 and 68% for S. agalactiae and S. aureus in camels, respectively. The CMT specificities were 91% for both the pathogens. 相似文献
6.
旨在揭示金黄色葡萄球菌针对β-内酰胺类抗生素可能存在细胞壁增厚的耐药机制。2016-2018年间，采集宁夏地区部分奶牛养殖场临床及亚临床型乳腺炎的乳样，通过显色培养基鉴别、镜检及PCR方法，分离鉴定牛乳源金黄色葡萄球菌；利用微量肉汤稀释法测定细菌对14种抗菌药物的耐药性，了解本地区金黄色葡萄球菌的耐药率及多重耐药情况；通过qRT-PCR方法检测细胞壁增厚相关的pbpB、murG、glmU、atlR基因转录丰度，并结合透射电镜进行形态观察，以确定增厚及发生原因。结果显示，分离鉴定出261株牛乳源金黄色葡萄球菌，其中包括9株耐甲氧西林金黄色葡萄球菌（methicillin-resistant Staphylococcus aureus，MRSA）。药敏试验结果显示，金黄色葡萄球菌对β-内酰胺类抗生素具有较高的耐药率，其中氨苄西林为79.69%，青霉素为78.54%。多重耐药情况是以3、7和8重耐药的菌株居多；其中1株耐药种数达14种之多。qRT-PCR结果表明，4种相关基因的转录丰度均极显著上调（P<0.001或P<0.01）。透射电镜观察发现，甲氧西林敏感的金黄色葡萄球菌（methicillin sensitive Staphylococcus aureus，MSSA）JY21菌株的细胞壁在64和128 μg·mL-1的青霉素浓度下，较对照组均极显著增厚（P<0.001），并可见细胞壁表面粗糙，有结节状凸起；但药物浓度从64 μg·mL-1升高至128 μg·mL-1细胞壁不再显著增厚（P>0.05）。MRSA WLD10菌株细胞壁未出现明显增厚（P>0.05）。综上所述，本地区牛乳源金黄色葡萄球菌针对β-内酰胺类抗生素，存在细胞壁增厚的耐药机制；增厚的原因主要是肽聚糖的过度合成及细胞自溶的减少。与MSSA JY21菌株相比，细胞壁增厚并非MRSA WLD10重要的耐药机制。 相似文献
7.
Screening of subclinical mastitis under field conditions is done using the California mastitis test (CMT). CMT score of ≥1 corresponding to ≥500,000 somatic cells ml−1 is commonly used as threshold of subclinical mastitis in temperate countries. However, given the innately high physiological level of somatic cells in low yielding dairy cows, this threshold may not apply to low yielding dairy cows. The current study was undertaken to investigate the clinical utility of CMT for screening of Staphylococcus aureus subclinical mastitis in low yielding smallholder dairy cows in Tanzania. A total of 1151 of quarter-milk samples were CMT tested, of these 914-originated from cows with a lactation period of 14–305 days. All samples were screened for subclinical mastitis by the CMT as well as microbiological culture of single, duplicate (two consecutive) and triplicate (three consecutive) samples as a gold standard. For the duplicate and triplicate quarter-samples, cows were considered positive for S. aureus subclinical mastitis if results of microbiologic culture for S. aureus were positive for two of two, and for at least two of the first three consecutive quarter-milk samples collected from that cow, respectively. Using a CMT score of ≥1 would classify 78.6% of the 940 quarter-samples as positive. Eighty-two percent of the samples in which S. aureus was isolated had CMT scores ≥2; this would classify 51.6% of the 940 quarter-samples as positive. For the single sample, this cut-off had sensitivity, specificity and likelihood ratio for S. aureus of 0.87, 0.83 and 4.24, respectively. For the duplicate quarter-milk samples this cut-off had sensitivity, specificity, and likelihood ratio of 0.94, 0.86, and 5.19. While, for the triplicate quarter-milk samples this cut-off had sensitivity, specificity and likelihood ratio of 0.97, 0.92 and 7.47, respectively. Based on these results and practical considerations, it is concluded that CMT score of ≥2 corresponding to ≥800,000 somatic cells Ml−1 is the best cut-off to correctly identify S. aureus intramammary infections in low yielding dairy cows in Tanzania. 相似文献
8.
J.P. Varshney M.P. Kapur Anshu Sharma 《Comparative immunology, microbiology and infectious diseases》1993,16(4):317-321
A total of 49 isolates of Staphylococcus aureus of buffalo mammary origin were studied for biochemical characteristics. Coagulase production, clumping factor, haemolytic activity, pigment production and fermentation of maltose and mannitol were employed to differentiate S. aureus from S. hyicus and S. intermedius. Out of 49 isolates, 97.95, 93.87, 93.87, 89.79, 95.91, 100.0, 95.91, 59.18, 100.0, 100.0, 100.0, 89.79, 91.83 and 100.0% isolates were positive for coagulase production, protein-A production, haemolysin production, thermostable nuclease production, deoxyribonuclease production, tellurite reduction, nitrate reduction, lipase production, phosphatase production, mannitol fermentation, glucose fermentation, M.R. test, V.P. test and pigment production respectively. The only isolate from which coagulase production could not be detected, however, showed haemolytic activity, protein-A productivity, pigmentation and mannitol fermentation. One of the protein-A negative isolate was coagulase positive and showed mennitol fermentation, pigmentation and haemolytic activity. The study revealed that the biochemical characteristics of S. aureus of buffalo mammary origin did not differ from those of cattle origin. Coagulase, haemolysin, thermostable nuclease, deoxyribonuclease, phosphatase, lipase, tellurite and nitrate reduction closely related with protein-A. The presence of protein-A seems to be as reliable an indicator for S. aureus of buffalo origin as is coagulase production. 相似文献
9.
为探明牦牛隐性乳房炎（SCM）主要病原菌及其耐药和毒力基因的分布情况，本研究自甘肃省甘南州夏季牧场收集无乳房炎临床症状牦牛乳样，通过兰州乳房炎试验（LMT）筛选SCM乳样，从中分离病原菌并纯化培养，利用16S rDNA鉴定主要病原菌，通过纸片扩散法判定其药物敏感性，并采用PCR方法对相关耐药及毒力基因进行检测。结果显示，共筛选出牦牛SCM乳样324份，检出率14.43%；主要病原菌为葡萄球菌属、埃希氏菌属和肠球菌属，其中葡萄球菌分离株对青霉素和四环素耐药率最高，分别为59.57%和47.52%；大肠埃希氏菌分离株对四环素和氨苄西林耐药率最高，分别为43.40%和20.75%；粪肠球菌分离株对四环素和红霉素耐药率最高，分别为25.00%和16.67%；59株耐青霉素金黄色葡萄球菌中共检出MRSA 12株，其中7株携带mecA基因，5株含mecC基因；四环素外排泵基因tetK、tetA携带率最高（85.45%、56.36%），核糖体保护基因tetM携带率最低（34.55%）；毒力基因中，clfA、clfB、fib、coa基因检出率较高（87.64%、84.27%、83.15%、82.02%）。研究表明，牦牛SCM的主要病原菌为金黄色葡萄球菌和大肠埃希氏菌，均对青霉素类和四环素类抗生素耐药性较高，其中金黄色葡萄球菌的主要毒力因子为黏附因子和凝固酶。 相似文献
10.
【目的】本研究旨在从金黄色葡萄球菌(Staphylococcus aureus,S.aureus,以下简称金葡菌)处理奶牛乳腺上皮细胞(bovine mammary epithelial cell,BMEC)上清中分离外泌体,探究金葡菌与BMEC数量比值(MOI)和处理后培养时间对外泌体总浓度的影响,并对金葡菌诱导BMEC释放的外泌体进行分离和鉴定。【方法】采用金葡菌临床分离菌株以MOI＝1和MOI＝10分别处理BMEC 3 h,对已处理的BMEC继续无外泌体培养9、12、24 h,同时设空白对照组,通过扫描电镜观察金葡菌处理对BMEC造成的超微结构损伤。采用超速离心法分离金葡菌诱导的BMEC上清液中的外泌体,分别用透射电镜、纳米颗粒追踪分析技术及Western blotting法对外泌体形态、颗粒大小和特异性标志蛋白进行分析鉴定。通过检测外泌体总蛋白浓度评估不同MOI和处理后培养时间对外泌体总量的影响,明确金葡菌诱导BMEC释放外泌体的最佳条件。【结果】通过扫描电镜观察发现,金葡菌处理BMEC后,细胞微绒毛脱落,细胞骨架破坏。透射电镜观察分离的外泌体为圆形的双层膜囊泡,直径在30~150 nm,形态均一。通过检测外泌体总蛋白浓度显示,在MOI＝10时,培养9、12和24 h金葡菌诱导BMEC释放外泌体蛋白浓度均高于MOI＝1,而培养12 h时释放外泌体蛋白浓度最高。对金葡菌诱导BMEC释放的外泌体进一步鉴定,其平均直径约为116 nm;Western blotting检测结果显示外泌体标记物CD9、CD81和TSG101表达阳性。【结论】本研究从形态学和分子生物学特征等方面证实获得的分离物为外泌体;金葡菌可以诱导BMEC释放外泌体,当MOI＝10时,金葡菌处理细胞3 h后继续无外泌体培养12 h,收获的细胞上清中外泌体蛋白含量最高。 相似文献
11.
本试验拟探究金黄色葡萄球菌（金葡菌）表面蛋白A（Staphylococcus aureus surface protein A，SasA）编码基因在奶牛乳源金葡菌中是否具有普遍性及同源性，并结合蛋白结构组成研究SasA对奶牛乳腺上皮细胞的黏附作用。试验前期从中国北方5个荷斯坦牛场无菌条件下分离纯化了73株奶牛乳源金黄色葡萄球菌菌株，PCR扩增鉴定SasA基因并进行序列保守性分析。利用原核表达系统表达SasA蛋白的丝氨酸富集片段1（serine-rich repeat region 1， SRR1）及非重复区域（non-repeat region， NRR）并进行蛋白纯化。利用流式细胞仪检测NRR，牛血清白蛋白（bovine serum albumin， BSA）及SRR1对奶牛乳腺上皮细胞（Mac-T）黏附性差异。为进一步在NRR中定位发挥主要黏附作用的片段，试验采用了长度不同的NRR片段与完整NRR片段做竞争性黏附处理。PCR扩增产物鉴定及序列同源性分析结果显示，86.3%的牛源金葡菌菌株含SasA基因且序列一致性超过95%。相较于SRR1和BSA，NRR对细胞具有更强的黏附性。黏附抑制试验结果表明，NRR1-2片段（230—540 aa）对NRR抑制作用最明显。综上表明，SasA基因在奶牛乳源金葡菌中具有普遍性，该基因序列具有高度的保守性。在SasA蛋白中，对奶牛乳腺上皮细胞起主要黏附作用的为NRR1-2片段，大致定位在其结构域的230—540位氨基酸。本研究结果表明，与该区域结合的受体中可能存在SasA作为黏附素与奶牛乳腺上皮细胞互作的位点。 相似文献
12.
Differentially expressed genes associated with Staphylococcus aureus mastitis of Canadian Holstein cows 总被引：1，自引：0，他引：1
To study pathway specific gene expression within the immune-endocrine axis of dairy cows with Staphylococcus aureus mastitis, mRNA was collected from blood mononuclear cells (BMCs) and milk somatic cells (MSCs) of cows (n = 7) identified as culture positive for S. aureus and their matched negative control cows (n = 7) with no evidence of S. aureus mastitis. Labeled cDNA probes derived from BMCs and MSCs of infected and healthy cows were applied to a bovine immune-endocrine cDNA array containing 167 genes. Genes with a log2 ratio ≥ 0.5 were considered to be up-regulated and genes with a log2 ratio ≤ −0.5 to be down-regulated. In total, 22 genes were differentially displayed in BMCs and 16 genes in MSCs of case versus controls. Expression of selected genes in BMCs and MSCs were confirmed by real-time PCR. The RT-PCR results were highly correlated with microarray measurements. Some of these genes, such as interleukin (IL)-8 have been previously implicated in other bacterial diseases, and are known to regulate immune responses; whereas, others may reflect novel pathways or genes involved in progressive mammary gland disease. For example, IL-18 was up-regulated in BMCs but not MSCs of mastitic quarters, while IL-17 was more highly expressed in MSCs compared to BMCs. This study identified a number of differentially expressed genes associated with bovine S. aureus mastitis and demonstrates the intricacy of the patterns of gene expression that influence host response to a complex pathogen of significant relevance to both human and veterinary medicine. 相似文献
13.
The activity of a range of antibiotics on intracellular Staphylococcus aureus was examined using an in vitro system in which staphylococci survived within bovine neutrophils and extracellular organisms were killed by lysostaphin. Cloxacillin in the presence of lysostaphin caused a reduction in the number of viable intracellular S. aureus but cloxacillin alone failed to reduce such bacteria significantly. The cloxacillin appeared to sensitize the staphylococci to lysis by extracellular traces of lysostaphin following neutrophil disruption. Extracellular staphylococci which remained viable after exposure to cloxacillin in the absence of lysostaphin were subsequently killed more rapidly by neutrophils, but this was not found with bacteria exposed to cloxacillin while inside cells. Vancomycin with lysostaphin produced a similar but smaller sensitization effect but this antibiotic also appeared to increase survival of intracellular staphylococci when compared with controls, possibly by impeding neutrophil bactericidal mechanisms. The only other antibiotic to show significant intracellular killing was rifampicin, and in this case the action was independent of lysostaphin. 相似文献
14.
Staphylococcus aureus(SA)bovine mastitis is a chronic and subclinical infectious disease, which is hard to control. It brings unpredictable losses to dairy-farming industry. Immune escape effect of SA plays an important role in the occurrence and development of mastitis, and some virulence factors are mostly associated with the immune evasion of bacteria. In this paper, some important immune evasion mechanisms of SA in recent researches were reviewed in order to provide theoretical reference for further prevention and treatment of mastitis in dairy cows. 相似文献
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旨在探究金黄色葡萄球菌（Staphylococcus aureus，简称金葡菌）对小胶质细胞α干扰素（interferon α，IFN-α）生成的影响，本研究先用金葡菌感染BV2细胞，检测IFN-α的mRNA表达、分泌到细胞培养液上清的量以及TBK1/IRF3通路的激活情况，再分别用TBK1抑制剂BX-795和amlexanox、NF-κB抑制剂IMD-0354处理细胞，检测TBK1/IRF3的激活以及IFN-α水平。结果表明，BV2感染金葡菌后，IFN-α转录水平在3~12 h升高，6~12 h释放量增加，呈剂量依赖性，TBK1和IRF3的转录水平和蛋白水平未发生变化，但在1~12 h其磷酸化水平升高，表明金葡菌激活BV2细胞TBK1/IRF3通路，BX-795、amlexanox和IMD-0354处理细胞后，IRF3磷酸化水平降低，IFN-α生成减少，表明TBK1和NF-κB参与金葡菌促进BV2细胞生成IFN-α。综上所述，金葡菌感染BV2后促进IFN-α生成，且该过程依赖于TBK1和NF-κB，本结果为临床防治中枢神经系统感染金葡菌提供了可能靶点和理论基础。 相似文献
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In order to establish the mouse mastitis model induced by Staphylococcus aureus small colony variants (SCVs),40 BALB/c mice 6 to 8 days postpartum were randomly divided into eight groups,negative control group,physiologic saline group and six treated groups with different doses (1.0×103,1.0×104 and 1.0×105 CFU/mL) of Staphylococcus aureus SCVs or Staphylococcus aureus quality control strains.50 μL physiologic saline and Staphylococcus aureus liquid were injected into the forth mammary glands in physiologic saline group and the six treated groups,respectively.All the mice were sacrificed 24 h after treatment.One side of the forth mammary glands was used to make pathological section,the other side was used to detect the concentration of TNF-α in the supernatant.The results showed that mice had different degrees of clinical symptoms in the treated groups,their mammary glands appeared different degrees of inflammatory symptoms and pathological changes.Under the same injected dose,the Staphylococcus aureus quality control strains group pathologic changed more severe than the Staphylococcus aureus SCVs group.The experimental data had been statistically analyzed by using SPSS software,the result showed that the expression of TNF-α of the Staphylococcus aureus quality control strains group were extremely significantly higher than that of Staphylococcus aureus SCVs group with high dose (P<0.01).The results indicated that Staphylococcus aureus and its SCVs could be used to establish the mice mastitis model,and Staphylococcus aureus SCVs caused relatively minor inflammation than the normal strains.The results provided a new research materials and meaningful exploration to research the prevention and control of chronic mastitis cows and its pathogenic mechanism caused by Staphylococcus aureus SCVs,and laid the foundation for studying the deeper relationship between Staphylococcus aureus SCVs and chronic mastitis. 相似文献
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为了建立由金黄色葡萄球菌小菌落突变株(small colony variants,SCVs)诱发感染乳房炎动物模型,本试验取40只分娩6~8 d的BALB/c小鼠,随机分成8组(n=5),分别为阴性对照、生理盐水组和不同剂量金黄色葡萄球菌SCVs及金黄色葡萄球菌质控菌株(1.0×103、1.0×104、1.0×105 CFU/mL)试验组,对生理盐水组及各试验组小鼠第4对乳腺注射生理盐水和对应剂量的菌液(50 mL/只),注射后24 h解剖观察病理变化,一侧乳头制作石蜡切片,另一侧研磨后用ELISA检测试剂盒检测组织匀浆上清中的TNF-α含量。结果显示,注射菌液的试验组,小鼠均出现不同程度的临床症状,乳腺出现不同程度的炎性症状和病理变化。同一注射剂量下,金黄色葡萄球菌质控菌株较金黄色葡萄球菌 SCVs病理变化严重,通过SPSS等软件对试验数据进行统计分析后得出,高浓度处理组金黄色葡萄球菌质控菌株的TNF-α表达量极显著高于金黄色葡萄球菌SCVs(P<0.01)。结果表明,金黄色葡萄球菌及其SCVs均可用来建立小鼠乳房炎模型,且金黄色葡萄球菌SCVs引起的情况较其正常株轻微,这一结果为由金黄色葡萄球菌SCVs引起的奶牛慢性乳房炎的预防和控制及其致病机制的研究提供了新的材料和有益的探索,为SCVs与慢性乳房炎更深层次关系的研究奠定基础。 相似文献
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为了研究前列腺素D2（prostaglandin D2,PGD2）/DP1受体途径对大肠杆菌（Escherichia coli）和金黄色葡萄球菌（Staphylococcus aureus）感染奶牛子宫内膜组织中炎症介质HMGB-1和PAFR的表达及对组织损伤程度的影响,试验以体外培养奶牛子宫内膜组织为研究对象,应用1×10-6 mol/L DP1受体激动剂（BW-245C和15d-PGJ2）和等量（1×106 CFU/mL）大肠杆菌、金黄色葡萄球菌共同处理奶牛子宫内膜组织,采用实时荧光定量PCR、免疫组化和HE染色法检测奶牛子宫内膜组织中HMGB-1和PAFR的表达并评价组织损伤情况。结果显示,与空白对照组相比,大肠杆菌和金黄色葡萄球菌感染奶牛子宫内膜组织中HMGB-1和PAFR表达量显著升高（P<0.05）,而DP1受体激动剂与大肠杆菌和金黄色葡萄球菌共处理奶牛子宫内膜组织中DP1受体激动剂显著抑制奶牛子宫组织中HMGB-1和PAFR的表达（P<0.05）。HE染色结果显示,大肠杆菌与金黄色葡萄球菌感染的奶牛子宫内膜组织上皮细胞和腺上皮细胞完全脱落、坏死、崩解;而DP1受体激动剂、大肠杆菌、金黄色葡萄球菌共同处理奶牛子宫内膜组织中,DP1受体激动剂的加入显著减轻奶牛子宫内膜组织的损伤程度（P<0.05）。免疫组化染色法结果与以上两种方法结果一致。结果表明,PGD2能够抑制大肠杆菌与金黄色葡萄球菌感染的奶牛子宫内膜组织中损伤相关因子HMGB-1、PAFR的表达,减轻组织损伤程度,这一作用可能是由DP1受体所介导的。 相似文献
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旨在探讨金黄色葡萄球菌（S.aureus）型和大肠杆菌（E.coli）型乳腺炎奶牛乳腺组织的炎症相关因子基因的mRNA转录水平。将105 CFU·mL-1的S.aureus和E.coli经乳导管分别注入奶牛乳房,在感染第7天采用活体无菌手术法采集乳腺组织,并采用组织HE染色和免疫荧光法进行乳腺炎模型的鉴定;利用qPCR分别检测了2个诱导组和对照组奶牛乳腺组织的趋化因子家族（CCL2、CCL8、CXCR1、CXCL2和CXCL13）、补体因子（CFI和CFB）、自噬调节因子DEPP1和白细胞介素受体IL21R共9个基因的mRNA转录水平。结果显示：与对照组相比,TLR4/NF-κB炎症相关信号通路中的关键分子（TLR4、NF-κB和TNFα）在2个诱导组乳腺组织中的蛋白表达水平均极显著上调（P<0.01）;结合HE染色结果,表明本试验成功构建了2种类型的奶牛乳腺炎活体模型。mRNA转录水平的检测结果表明,与对照组相比,7个基因（CCL2、CCL8、CXCR1、CXCL2、CFI、CFB和IL21R）在2个诱导组乳腺组织中的mRNA转录水平均极显著上调（P<0.001）,CXCL13的mRNA转录水平仅在S.aurues诱导组乳腺组织中极显著上调（P<0.01）;DEPP1的mRNA转录水平在2个诱导组中均极显著下调（P<0.01）。此外,CCL2、CCL8、CXCR1、CFI和IL21R共5个基因在E.coli诱导组中的mRNA转录水平均极显著高于S.aureus组（P<0.01）。S.aureus和E.coli感染均可导致奶牛产生严重的临床乳腺炎症状,并促使上述炎症相关基因的mRNA转录水平在乳腺组织中发生变化,以应对乳腺炎症的发生与发展过程;趋化因子CCL2等5个基因在E.coli诱导组中的mRNA转录水平显著高于S.aureus诱导组,解释了E.coli常常能引起急性乳腺炎,而S.aureus可引起慢性乳腺炎的原因。上述结果可为深入研究不同类型乳腺炎的分子调控机制提供参考。 相似文献