生物材料植入后发生感染与表皮葡萄球菌生物膜

表皮葡萄球菌是生物材料植入后发生感染的主要条件致病菌,细菌生物膜的形成是导致生物材料植入后感染难治性的主要根源。文章就表皮葡萄球菌生物膜、生物材料植入后发生感染与表皮葡萄球菌生物膜进行综述,同时阐述生物材料表面细菌生物膜的研究方法。     

血糖对树鼩感染表皮葡萄球菌清除能力及植入性材料细菌黏附性的影响

背景：高浓度葡萄糖培养条件下,细菌在生物材料表面有较强的生物膜形成能力。 目的：观察血糖升高对表皮葡萄球菌在动物体内清除能力及植入性生物材料上细菌生物膜形成的影响。 方法：注射链脲佐菌素建立高血糖树鼩模型(血糖≥11.1 mmol/L),采用生物膜形成阳性与阴性表皮葡萄球菌感染高血糖与正常对照树鼩,并同时在动物股静脉内植入PVC导管。 结果与结论：感染生物膜形成阳性的表皮葡萄球菌株后,血糖≥11.1 mmol/L树鼩血液、心脏、肝脏、肾脏、胰腺的细菌感染率及菌落计数较正常对照组高(P < 0.05);扫描电镜观察血糖≥11.1 mmol/L组植入生物材料上有明显的生物膜形成。感染生物膜形成阴性表皮葡萄球菌株后无论血糖高低,均未观察到生物膜形成。表明血糖升高不仅使植入生物材料树鼩的细菌清除能力下降,同时可诱导细菌在植入生物材料表面形成明显的生物膜。     

表皮葡萄球菌ica操纵子与生物材料感染

表皮葡萄球菌是医院感染的主要条件致病菌,常伴随医用生物材料进入体内并通过黏附形成细菌生物膜.表皮葡萄球菌生物膜是具有高度组织化的多细胞群体结构,生物膜的形成是以生物材料为中心的感染难治性的关键所在.对生物材料相关感染、表皮葡萄球菌ica操纵子与生物膜形成、生物膜治疗及其研究方法等问题进行了综述,指出目前有关表皮葡萄球菌生物膜致病的研究多局限于实验室突变菌株及浮游生长方式获得,未能完全反映临床表皮葡萄球菌生物膜致病的自然情况,因此应进一步研究临床生物材料应用发生的感染中,表皮葡萄球菌生物膜的形成及其防治的方法.     

agrC对表皮葡萄球菌生物膜形成作用机制的研究进展

表皮葡萄球菌在医用生物材料表面形成的生物膜可有效抵御抗生素的治疗,导致感染迁延不愈,已成为近年来的研究热点.影响生物膜形成的众多基因构成了复杂的调控网络,在生物膜形成的不同阶段发挥不同的作用,其中表皮葡萄球菌附属基因调节子(agr)系统是调节生物膜形成的最重要基因之一.就细菌生物膜的形成过程、agr系统及其相关基因对生物膜形成调控机制的研究现状进行综述,为研究以agr为靶点治疗表皮葡萄球菌生物膜引发的相关感染提供参考.     

表皮葡萄球菌生物被膜结构观察

随着生物材料被广泛应用于临床,表皮葡萄球菌已经成为医院感染的主要条件致病菌.生物材料表面细菌生物被膜(biofilm,BF)的形成是导致感染反复发作及久治不愈的根本原因,且常常引发灾难性的后果[1].本研究通过建立医用生物材料聚氯乙烯(polyvinyl chloride,PCV)表面表皮葡萄球菌BF体外模型,观察PVC材料表面细菌BF的结构,为生物材料植入感染研究提供实验模型和方法.     

肺癌患者中心静脉导管相关表皮葡萄球菌icaA、icaD表达及转化生长因子β1与 生物膜的关系**☆

背景：研究证实,以生物材料为中心的感染细菌临床株致病力与其在中心静脉导管材料表面形成细菌生物膜的能力呈正相关。 目的：分析肺癌患者中心静脉导管相关表皮葡萄球菌icaA、icaD mRNA表达及外周血转化生长因子β1水平与细菌生物膜形成的关系。 方法：种属鉴定相关性血流感染肺癌患者表皮葡萄球菌类型后行细菌基因组 DNA 抽提,PCR法检测生物膜形成相关基因icaA、icaD mRNA表达及生物膜表型。酶联免疫吸附试验检测相关性血流感染与未感染肺癌患者血清转化生长因子β1水平。 结果与结论：相关性血流感染肺癌患者表皮葡萄球菌操纵子icaA、icaD基因表达与生物膜形成呈正相关(P < 0.01),且表皮葡萄球菌生物膜阳性患者外周血转化生长因子β1水平较无相关性血流感染肺癌患者高(P < 0.05)。表明置入中心静脉插管引起表皮葡萄球菌感染icaA、icaD基因表达阳性肺癌患者较易形成细菌生物膜,外周血高水平转化生长因子β1对细菌生物膜形成有积极作用。     

高浓度葡萄糖对表皮葡萄球菌生物膜在生物材料表面形成的影响

背景:因植入性材料所带来的生物材料感染在糖尿病患者中较高,在非糖尿病手术期间存在高血糖的患者也有较高感染率。在体外研究不同浓度血糖对生物材料上形成细菌生物膜的影响报道较少。目的:观察高浓度葡萄糖对表皮葡萄球菌生物膜在生物材料表面形成的影响。方法:采用不同浓度葡萄糖培养表皮葡萄球菌感染模型。结晶紫染色法对生物膜进行半定量检测,激光共聚焦显微镜观察生物膜的厚度。结果与结论:半定量实验显示生物膜形成阳性株(表皮葡萄球菌ATCC35984)吸光度值均大于0.12,随着培养基中葡萄糖浓度的增加,其吸光度值呈上升趋势,而在50mmol/L葡萄糖浓度时其吸光度值最高。激光共聚焦显微镜观察生物膜形成阳性株(表皮葡萄球菌ATCC35984)中,≥11.1mmol/L葡萄糖各组与无葡萄糖组相比,其生物膜厚度明显增加(P0.05)。生物膜形成最高值在50mmol/L组。生物膜形成阴性株(表皮葡萄球菌ATCC12228)中均无明显生物膜形成。结果表明高浓度葡萄糖明显诱导表皮葡萄球菌生物膜的形成,控制血糖是降低糖尿病生物材料感染的重要措施之一。     

夫西地酸钠联合利福平对表皮葡萄球菌体外培养生物膜的作用

背景：表皮葡萄球菌是材料植入后感染的主要病原体,致病机制是在材料表面形成生物膜,生物膜形成后,单一用药抑制其细菌生长的效果较差。 目的：建立表皮葡萄球菌生物膜体外模型,观察夫西地酸钠联合利福平对表皮葡萄球菌体外培养生物膜的作用。 方法：体外培养生物膜,微量肉汤稀释法检测最低抑菌浓度,将低于最低抑菌浓度的夫西地酸钠和利福平单独或联合使用作用于表皮葡萄球菌早期与成熟期生物膜,观察其对表皮葡萄球菌早期和成熟生物膜的影响。 结果与结论：夫西地酸钠和利福平均可抑制表皮葡萄球菌的黏附和生物膜的形成,对早期及成熟期生物膜内细菌有杀菌效应,二者联合应用后疗效明显优于单独应用(P < 0.05)。提示夫西地酸钠联合利福平可明显抑制抑制表皮葡萄球菌的黏附和生物膜的形成,对早期及成熟期表皮葡萄球菌-生物膜有破坏作用,具有明显杀菌活性,是治疗细菌生物被膜相关感染的良好选择。     

溴代呋喃酮对胸心外科聚氯乙烯材料表面金黄色葡萄球菌生物膜形成的影响

目的 探讨溴代呋喃酮对胸心外科聚氯乙烯(PVC)材料表面金黄色葡萄球菌生物膜形成的影响,为生物材料表面改性研究及临床生物材料植入感染的防治提供新思路.方法 选用具有化学结构代表性的3种溴代呋喃酮[呋喃酮1:3,4-二溴基-5-羟基-呋喃酮;呋喃酮2:4-溴-5-(4-甲氧基苯基)-3-(甲氨基)- 呋喃酮;呋喃酮3:3,4-二溴基-5,5-二甲苯基-2(5H)-呋喃酮]分别对PVC材料进行表面涂层改性,分别将改性过的PVC材料与金黄色葡萄球菌共同培育,激光共聚焦显微镜动态观察PVC材料表面细菌群落及细菌生物膜厚度的形成,扫描电子显微镜观察PVC材料表面细菌生物膜表面结构.结果 呋喃酮1组PVC材料表面金黄色葡萄球菌群落数量和细菌生物膜厚度明显大于对照组(P < 0.05),呋喃酮2、呋喃酮3组金黄色葡萄球菌群落数量和细菌生物膜厚度与对照组比较差异无统计学意义(P > 0.05).结论 不同溴代呋喃酮对PVC材料表面金黄色葡萄球菌生物膜形成的影响不同,呋喃酮1可以促进PVC材料表面金黄色葡萄球菌群落数量和细菌生物膜厚度的形成.     

SspA对生物材料细菌黏附及生物膜形成的影响

金黄色葡萄球菌(staphylococcusaureus,SA)是以生物材料为中心感染的主要致病菌之一,主要通过细菌黏附并形成生物膜造成感染,给患者带来灾难性的后果。SA的表面蛋白纤维连接蛋白结合蛋白(fibronectin-bindingprotein,FnBP)是其关键的黏附因子,而金黄色葡萄球菌丝氨酸蛋白酶(staphy-lococcalserineprotease,SspA)可降低细菌的FnBP,抑制自溶素(autolysin,AtlE)分泌,降解表面A蛋白(surfaceproteinA,Spa)从而抑制细菌黏附和生物膜(bacterialbiofilm,BF)的形成,为SspA在控制SA感染方面提供了一个重要的治疗途径。     

Lack of Association between fbe Gene with Adherence and Biofilm Forrr：ation in Staphylococcus epidermidis Clinical Isolates

Biofilm formation plays a major role in the pathogenesis of nosocomial infections caused by Staphylococcus epidermidis (S. epidermidis). It has been suggested that protein encoded by the foe (fibrinogen binding protein) gene of S. epidermidis enhances bacterial adherence to medical devices and biofilm formation by binding to host fibrinogen (Fg). In this study, a 1.7 kbfoe gene fragment was amplified in 111 of 115 strains of S. epidermidis chnical isolates using PCR. Contrary to expectations, only 14 strains showed marginally increased adherence to Fg-coated polystyrene wells compared with BSA coated wells. Quantitative real-time PCR revealed no statistically significant difference in Fbe expression between Fg binding strains and Fg non-binding strains. Fttahermore, in the presence of soluble Fg, S. epidermdis biofilm formation decreased in a dose-dependent manner. In contrast, the Staphylococcus aureus ( S. aureus ) strain Cowan I and other 5 S. aureus clinical isolates showed a substantial increase in both adherence and biofilm formation in the presence of Fg. The resuits suggest that in S. epidermidis the foe gene may not be associated with bacterial adherence and biofilm formation.     

Role of the luxS quorum-sensing system in biofilm formation and virulence of Staphylococcus epidermidis

Nosocomial infections caused by Staphylococcus epidermidis are characterized by biofilm formation on implanted medical devices. Quorum-sensing regulation plays a major role in the biofilm development of many bacterial pathogens. Here, we describe luxS, a quorum-sensing system in staphylococci that has a significant impact on biofilm development and virulence. We constructed an isogenic DeltaluxS mutant strain of a biofilm-forming clinical isolate of S. epidermidis and demonstrated that luxS signaling is functional in S. epidermidis. The mutant strain showed increased biofilm formation in vitro and enhanced virulence in a rat model of biofilm-associated infection. Genetic complementation and addition of autoinducer 2-containing culture filtrate restored the wild-type phenotype, demonstrating that luxS repressed biofilm formation through a cell-cell signaling mechanism based on autoinducer 2 secretion. Enhanced production of the biofilm exopolysaccharide polysaccharide intercellular adhesin in the mutant strain is presumably the major cause of the observed phenotype. The agr quorum-sensing system has previously been shown to impact biofilm development and biofilm-associated infection in a way similar to that of luxS, although by regulation of different factors. Our study indicates a general scheme of quorum-sensing regulation of biofilm development in staphylococci, which contrasts with that observed in many other bacterial pathogens.     

Vaccination with SesC Decreases Staphylococcus epidermidis Biofilm Formation

The increased use of medical implants has resulted in a concomitant rise in device-related infections. The majority of these infections are caused by Staphylococcus epidermidis biofilms. Immunoprophylaxis and immunotherapy targeting in vivo-expressed, biofilm-associated, bacterial cell surface-exposed proteins are promising new approaches to prevent and treat biofilm-related infections, respectively. Using an in silico procedure, we identified 64 proteins that are predicted to be S. epidermidis surface exposed (Ses), of which 36 were annotated as (conserved) hypothetical. Of these 36 proteins, 5 proteins-3 LPXTG motif-containing proteins (SesL, SesB, and SesC) and 2 of the largest ABC transporters (SesK and SesM)-were selected for evaluation as vaccine candidates. This choice was based on protein size, number of antigenic determinants, or the established role in S. epidermidis biofilm formation of the protein family to which the candidate protein belongs. Anti-SesC antibodies exhibited the greatest inhibitory effect on S. epidermidis biofilm formation in vitro and on colonization and infection in a mouse jugular vein catheter infection model that includes biofilms and organ infections. Active vaccination with a recombinant truncated SesC inhibited S. epidermidis biofilm formation in a rat model of subcutaneous foreign body infection. Antibodies to SesC were shown to be opsonic by an in vitro opsonophagocytosis assay. We conclude that SesC is a promising target for antibody mediated strategies against S. epidermidis biofilm formation.     

S. epidermidis biofilm formation: effects of biomaterial surface chemistry and serum proteins

Most infections due to implanted cardiovascular biomaterials are initiated by bacterial adhesion of Staphylococcus epidermidis, followed by colonization and biofilm formation on the surface of the implant. This study examined the role of serum proteins and material surface chemistry in the formation of S. epidermidis biofilm on polyurethanes (Elasthane 80A, hydrophobic) modified with polyethylene oxide (Elasthane 80A-6PEO, hydrophilic) and fluorocarbon (Elasthane 80A-6F, hydrophobic). Initial adhesion, aggregation, biofilm thickness, viability, and slime formation of S. epidermidis strain, RP62A in phosphate buffered saline (PBS), tryptic soy broth (TBS), and 20% pooled human serum was quantified. In the presence of adsorbed serum proteins, initial bacterial adhesion was suppressed significantly to <2% relative to adhesion in TSB or PBS. However, adhesion, aggregation, and proliferation increased dramatically in the 12-24 h period on Elasthane 80A and Elasthane 80A-6F, which resulted in an extensive network of biofilm. A contrasting trend was observed on the hydrophilic Elasthane 80A-6PEO surface, with minimal bacterial adhesion, which decreased steadily over 24 h. In the presence of serum proteins, an increasingly thick ( approximately 20 mum) biofilm formed on the hydrophobic surfaces over 48 h whereas the formation of a mature biofilm on the hydrophilic surface was impeded with few viable bacteria present over 48 h. Furthermore, slime was detected during the initial phase of bacterial adhesion at 2 h and increased over time with the formation of biofilm. These results have shown that while initial S. epidermidis adhesion is suppressed in the presence of adsorbed proteins, inter-bacterial adhesion possibly aided by slime production leads to the formation of a robust mature biofilm. Also, biomaterial surface chemistry affected biofilm formation and, most notably, polyethylene oxide significantly inhibited S. epidermidis biofilm formation over 48 h in vitro.