Antimicrobial activity of enrofloxacin against Staphylococcus intermedius strains isolated from canine pyodermas

This study examined and compared the minimal inhibition concentrations (MICs) of enrofloxacin against 393 Staphylococcus intermedius strains isolated in France from canine pyodermas during three different years, 1995 (174 isolates), 1997 (101 isolates) and 1999 (118 isolates). The MICs of enrofloxacin against these strains ranged from 0.063 to 64 mg L^?1, with MIC₅₀ and MIC₉₀ equal to 0.125 and 0.25 mg L^?1, respectively. Two resistant strains were found, but only among isolates collected in 1999. The data show that resistance to enrofloxacin among S. intermedius strains is still rare in dogs, but the selection in vitro of variants in which the MICs were increased 4–16‐fold after 10 serial passages in subinhibitory concentrations of enrofloxacin suggests that inappropriate use might favour the development of resistant strains in vivo.     

A model to determine sampling strategies and milk inoculum volume for detection of intramammary Staphylococcus aureus infections in dairy cattle by bacteriological culture

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.     

奶牛乳房炎病例中金黄色葡萄球菌RAPD-PCR基因分型的研究

用随机扩增多态性DNA 技术（RAPD）对来自2个集约化奶牛场不同奶牛乳房炎病例分出的16株金黄色葡萄球菌进行了基因分型。分别用3个寡核苷酸引物扩增，仅OLP11引物可扩增出质量良好、具有RAPD特征的条带图谱。对反应体系的退火温度、模板浓度进行了筛选，模板原倍浓度、33℃的退火温度能使所有检测菌株产生清晰、可分辨、具有较好重复性的带谱。分型结果表明，16株菌可分为2个类群，其中14株位于同一类群，大多数菌株的相关系数差距仅为0.04，这一结果提示这些菌株可能具有相同的来源和相似的遗传背景。     

PCR-based detection of genes encoding virulence determinants in Staphylococcus aureus from bovine subclinical mastitis cases

The present study was carried out to genotypically characterize Staphylococcus aureus (S. aureus) isolated from bovine mastitis cases. A total of 37 strains of S. aureus were isolated during processing of 552 milk samples from 140 cows. The S. aureus strains were characterized phenotypically, and were further characterized genotypically by polymerase chain reaction using oligonucleotide primers that amplified genes encoding coagulase (coa), clumping factor (clfA), thermonuclease (nuc), enterotoxin A (entA), and the gene segments encoding the immunoglobulin G binding region and the X region of protein A gene spa. All of the isolates yielded an amplicon with a size of approximately 1,042 bp of the clfA gene. The amplification of the polymorphic spa gene segment encoding the immunoglobulin G binding region was observed in 34 isolates and X-region binding was detected in 26 isolates. Amplification of the coa gene yielded three different products in 20, 10, and 7 isolates. The amplification of the thermonuclease gene, nuc, was observed in 36 out of 37 isolates. All of the samples were negative for the entA gene. The phenotypic and genotypic findings of the present strategies might provide an understanding of the distribution of the prevalent S. aureus clones among bovine mastitis isolates, and might aid in the development of steps to control S. aureus infections in dairy herds.     

病毒细菌协同凝集试验在蔬菜病毒检测中的应用

在蔬菜病毒病的病毒细菌协同凝集试验（简称ＶＢＡ法）中,首次比较了金黄色葡萄球菌Ｃｏｍｎ１和Ｎｏ．１８００菌株对ＶＢＡ灵敏度的影响,结果表明用Ｎｏ．１８００菌株代替国内、外通用的Ｃｏｍｎ１菌株,ＶＢＡ检测ＴｏＭＶ、ＣＭＶ和ＰＶＸ纯病毒的灵敏度提高了２～１０倍,达３．４～１３．０ｎｇ／ｍＬ,检出病汁液的最大稀释度达１０３～１０５,其灵敏度接近于Ａ蛋白酶联法。在此基础上,又将经抗血清致敏的金黄色葡萄球菌液体免疫剂冷冻干燥,制成一种新型的固体免疫剂,可在４℃下保存;在－１０℃贮藏１年后,用ＶＢＡ法检测ＴｏＭＶ、ＣＭＶ和ＰＶＸ纯病毒的灵敏度分别为８１、２０５和２１０ｎｇ／ｍＬ;即使在１５℃下贮藏１年,灵敏度仍高达２～６μｇ／ｍＬ;在２５℃下贮藏３个月,还有一定的效价。而液体免疫剂不能在１５℃下贮藏;在４℃下贮藏１０个月即失效。因此,固体免疫剂既保持了原液体免疫剂灵敏度高、特异性强、快速简便和经济的特点,又增加了耐贮藏的优点,更加适合在基层单位推广使用。     

鸡外周血白细胞吞噬试验的研究

[目的]确定鸡外周血白细胞吞噬葡萄球菌的最佳条件。[方法]使用葡萄球菌10145为吞噬材料,以瑞士染色法检测鸡外周血白细胞的吞噬活性。通过正交试验研究吞噬时间、吞噬温度、葡萄球菌浓度对外周血白细胞吞噬百分率(PP)和吞噬指数(PI)的影响,并对其进行形态观察。[结果]细菌浓度是影响白细胞吞噬指数的主要因素,白细胞吞噬指数最高的条件为:温度41℃,时间40 min,菌液浓度为5×106个/ml。各因素对白细胞吞噬指数的影响程度为:细菌浓度>时间>温度。[结论]该研究为白细胞吞噬功能的检测提供了一种较为简便、可靠的方法。     

天刃牌消毒液对4种细菌的抑菌和杀菌效果

将天刃牌消毒液(pH值为6.5和7.5)按照不同的稀释度稀释后与炭疽芽孢杆菌、金色葡萄球菌、鼠伤寒沙门氏菌、大肠杆菌分别作用不同时间,进行抑菌、杀菌效果的检测。结果表明,2种pH值消毒剂在不同稀释倍数下对4种细菌均有一定的抑制和杀灭作用。     

牛源抗金黄色葡萄球菌α溶血素单链抗体研制

由金黄色葡萄球菌引起的奶牛乳腺炎给养殖业造成了严重损失,抗生素是治疗奶牛乳腺炎的首选方法,但易出现耐药菌株。而目前针对金黄色葡萄球菌的疫苗也不能对奶牛乳腺炎提供足够的保护,疫苗的主要作用机理是激发机体产生抗体,故被动免疫针对金黄色葡萄球菌毒力因子的抗体也许能对感染起到一定的治疗作用。本研究首先扩增得到影响其致病性的重要毒力因子-α溶血素(Hla)的编码基因,然后将其转化到E.coli中进行表达并纯化,再以此纯化产物为抗原,从牛源噬菌体单链抗体表达文库中筛选到了一株针对α溶血素(Hla)高亲和力的scFv,最终将该scFv进行纯化。本研究一方面为治疗金黄色葡萄球菌所致奶牛乳腺炎提供一种新思路,另一方面也为分子水平上研究α溶血素的致病机制提供了有效的阻断分子。     

混合发酵剂对发酵香肠脂肪酸败和蛋白质氧化的影响

为了探究混合发酵剂对猪肉香肠脂肪酸败和蛋白质氧化的影响,测定接种植物乳杆菌及模仿葡萄球菌后猪肉香肠在发酵及后熟过程中菌落总数、乳酸菌总数、pH、巯基质量摩尔浓度、羰基质量摩尔浓度、硫代巴比妥酸（TBARS）值及感官评分随时间的变化,并与自然发酵组进行比较。结果表明：在发酵后熟期间,接种发酵组猪肉香肠的菌落总数、pH、肌原纤维蛋白的羰基质量摩尔浓度、TBARS值均显著低于自然发酵组,接种发酵组猪肉香肠的乳酸菌总数、肌原纤维蛋白的巯基质量摩尔浓度及感官评价（尤其是滋味和气味）显著高于自然发酵组。说明植物乳杆菌及模仿葡萄球菌对猪肉香肠的发酵抑制了猪肉香肠的蛋白质氧化及脂肪酸败,同时对猪肉香肠的感官品质有重要的改善作用。     

利奈唑胺治疗耐甲氧西林金黄色葡萄球菌肺炎的疗效及影响因素分析

目的 分析利奈唑胺治疗耐甲氧西林金黄色葡萄球菌(MRSA)肺炎的疗效、影响因素及安全性.方法 回顾性分析41例利奈唑胺治疗MRSA肺炎的临床资料.结果 利奈唑胺治疗MRSA肺炎的有效率为78.0%,细菌清除率为73.2%,不良反应率为2.4%.血培养阳性、合并感染性心内膜炎者的临床疗效及细菌清除率明显降低(P＜0.05...