聚合酶链反应检测石蜡切片中金黄色葡萄球菌DNA的研究

目的　探讨聚合酶链反应技术 (PCR)在检测石蜡包埋组织中金黄色葡萄球菌DNA的应用及价值。方法　利用PCR技术 ,对 55例福尔马林固定、石蜡包埋小鼠组织中SA DNA进行了检测。结果　 55例石蜡包埋的小鼠组织中均检测到SA DNA ,这与临床病理诊断为金黄色葡萄球菌 (S .aureus)感染相一致。结论　PCR技术可用于检测石蜡包埋组织中的SA DNA片段 ,为鼠S .aureus感染的回顾性分析提供了有效手段     

Plasmids from Staphylococcus aureus replicate in yeast Saccharomyces cerevisiae

It is known that some plasmids, such as RP4, can replicate in many Gram-negative bacteria. Certain small Staphylococcus aureus plasmids have an even broader host range, being able to replicate in not only phylogenetically distant Gram-positive bacteria such as Bacillus subtilis or Streptococcus pneumoniae, but also in the Gram-negative bacterium Escherichia coli. Here we have examined whether these plasmids can also replicate in a lower eukaryote, the yeast Saccharomyces cerevisiae. For this purpose we constructed hybrids between a S. aureus plasmid pC194 and an E. coli plasmid YIp5, which carries a ura-3 gene easy to select for in yeast but cannot replicate in this host. We found that the hybrids transformed yeast with high efficiency (as did hybrids between YIp5 and three other S. aureus plasmids); were maintained extrachromosomally in yeast; and were not modified during residence in yeast. We conclude from this evidence that S. aureus plasmids can replicate in yeast, which raises the questions of whether the replication signals used by prokaryotes and eukaryotes are similar, and how far up the phylogenetic tree the organisms still able to be hosts to S. aureus plasmids may be.     

Efficient inactivation of Staphylococcus aureus by silver and copper loaded photocatalytic titanate nanotubes

One dimensional titanate nanotubes(TNTs) were synthesized by microwave assisted alkaline hydrothermal process. The process was followed by UV-photodeposition of Ag and Cu on the surface of TNTs to enhance the photocatalytic activity in visible light spectrum. The loading of Ag and Cu(single and combination mode)offered a new insight to inactivate multi-drug resistant micro-organisms. The antibacterial properties of these samples were studied on Gram positive bacteria, Staphylococcus aureus(S. aureus) using well diffusion method.The TNTs with Ag and Cu loading showed a clear zone of inhibition after overnight incubation of S. aureus. The bacterial inactivation efficiency of nanoparticles in the visible light was further analyzed by kill kinetics. TNTs with Ag and/or Cu loading showed a significant reduction in bacterial growth. Cu co-loaded with Ag sample showed the highest inactivation efficiency within 90 min of visible light irradiation. To elucidate the mechanism of bactericidal properties of samples under visible light irradiation, the formation of reactive oxygen species(ROS), particularly, superoxide radical anion was determined by nitro blue tetrazolium(NBT) assay and the protein degradation by each samples were measured. Based on overall results, it was observed that the Cu coloaded with Ag on TNTs samples were found to be more effective as compared to either Ag or Cu loaded TNTs. It provides new avenues for utilizing the combination of Cu and Ag for enhancing the antimicrobial efficacies for different nanoparticles.     

Antibacterial Activity and Structure-Activity Relationships of Schiff Bases on Staphylococcus aureus by Microcalorimetry

The growth of Staphylococcus aureus under the action of six kinds of Schiff bases(A,B,C,D,E,F) was studied by means of microcalorimetry. Growth constant k and inhibition ratio I were calculated. Also,the antibacterial activity,the action characteristics and the structure-activity relationships of the compounds on S. aureus were analyzed. Results indicate that B,F show good antibacterial activity(IC50:293.6 mg · L-1 and 307.8 mg · L-1) ,D,E show moderate antibacterial activity(IC50:966.3 mg · L-1 and 1 126.7 mg · L-1) ,and A,C just show weak antibacterial activity(IC50 1 200 mg · L-1) . The I-c curves mainly present a straight line shape for B,D,E and F,but an inverse S shape for A and C. Structure-activity relationships analysis suggests that the species and position of the substituents determine the antibacterial activity of these Schiff bases,and the charge density distribution is one of the most important influencing factors.     

金黄色葡萄球菌功能蛋白的酵母表面展示

利用酿酒酵母表面展示系统,成功地将金黄色葡萄球菌功能蛋白ZZ锚定在酵母表面,并进一步用展示有蛋白ZZ的酵母细胞纯化出兔IgG.以pEZZ18为模板,通过PCR技术克隆了ZZ基因,将ZZ基因通过双酶切连接到穿梭载体pICAS,构建了酵母表面展示载体pICZZ,并将其转化至酿酒酵母(Saccharomyces cerevisiae)MT8-1中.核酸电泳结果表明ZZ基因成功整合到了酵母基因组中.重组菌经培养,利用免疫荧光染色方法进行染色,显微镜观察表明ZZ蛋白已经展示在酵母细胞表面,流式细胞仪分析结果证实80.4%的酵母细胞表达了ZZ蛋白.利用展示有蛋白ZZ的酵母细胞吸附兔血清中的IgG,洗脱后进行十二烷基磺酸钠-聚丙烯酰胺电脉,并进行W estern blot免疫印迹,结果表明,此重组酵母细胞纯化的兔IgG比标样兔IgG纯度更高.     

用生物素标记核酸探针检测鼠金黄色葡萄球菌的研究

利用聚合酶链反应技术从金黄色葡萄球菌基因组DNA中扩增出 6 78bp耐热核酸酶nuc基因特异性片段 ,经生物素标记后作为核酸斑点杂交试验的探针 ,对实验动物的金黄色葡萄球菌及其临床样品进行了检测。结果显示 ,标记探针与金黄色葡萄球菌DNA呈杂交阳性 ,而与链球菌、大肠埃希氏菌和巴氏杆菌DNA呈杂交阴性 ,斑点杂交的检测灵敏度为 1pg基因组DNA。用斑点杂交试验和PCR对 2 4 0份临床样品进行了检测 ,检出率为 2 9% (7 2 4 0 ) ,符合率为 10 0 %。这些试验结果表明 ,研究制备的核酸探针及建立的斑点杂交试验具有较高的特异性和敏感性 ,可用于实验动物金黄色葡萄球菌的快速检测     

几种表面活性剂对金黄色葡萄球菌生长的影响

在液体培养基中分别加入不同浓度不同种类的表面活性剂(AES、Tween-80、Tween-20和SDS),接种金黄色葡萄球菌,37℃恒温振荡培养,在不同培养时间测定培养液OD值,比较4种常用表面活性剂对金黄色葡萄球菌生长的影响.结果表明:4种表面活性剂对金黄色葡萄球菌的生长都表现出抑制作用,但抑制效应不同:AES对金黄色葡萄球菌生长的抑制作用最大,其次为Tween-80和Tween-20,SDS抑菌作用最弱.