金银花抑制大肠埃希菌生物膜活性部位的化学成分研究

目的:研究金银花抑制细菌生物膜有效部位中的化学成分。方法:采用微量板方法对金银花的有效部位进行追踪,并利用硅胶柱色谱等手段分离化学成分,并研究它们对细菌生物膜的影响。结果:乙醇洗脱部位为有效部位,并分离得到了15个化合物,分别为大豆脑苷Ⅱ(1)、5-O-咖啡酰基奎宁酸丁酯(2)、白果醇(3)、獐牙菜苷(4)、7-表断马钱子苷半缩醛内酯(5)、十八烷醇(6)、二十八烷醇(7)、原儿茶醛(8)、原儿茶酸(9)、肉桂酸(10)、咖啡酸(11)、熊果酸(12)、槲皮素(13)、齐墩果酸(14)、阿魏酸(15)。在质量浓度为1 g.L-1时,化合物4,5,12对大肠埃希菌生物膜的抑制率分别为36.16%,37.16%,46.18%。结论:化合物1首次从金银花中分离到,化合物4,5,12对大肠埃希菌生物膜有一定的抑制作用。     

Inhibition of bacterial growth and biofilm production by constituents from Hypericum spp

Biofilm embedded bacterial pathogens such as Staphylococcus spp., Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii are difficult to eradicate and are major sources of bacterial infections. New drugs are needed to combat these pathogens. Hypericum is a plant genus that contains species known to have antimicrobial properties. However, the specific constituents responsible for the antimicrobial properties are not entirely known, nor have most compounds been tested as inhibitors of biofilm development. The investigation presented here tested seven secondary metabolites isolated from the species Hypericum densiflorum, Hypericum ellipticum, Hypericum prolificum, and Hypericum punctatum as inhibitors of bacterial growth and biofilm production. Assays were conducted against Staphylococcus epidermidis, Staphylococcus aureus, clinical methicillin‐resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Escherichia coli, and Acinetobacter baumannii. Five of the seven compounds demonstrated growth inhibition against the Gram‐positive bacteria with minimum inhibitory concentrations (MIC) ranging from 1.95 µg/mL to 7.81 µg/mL. Four of the secondary metabolites inhibited biofilm production by certain Gram‐positive strains at sub‐MIC concentrations. Copyright © 2011 John Wiley & Sons, Ltd.     

Tyrosine phosphorylation and bacterial virulence

Protein phosphorylation on tyrosine has emerged as a key device in the control of numerous cellular functions in bacteria.In this article,we review the structure and function of bacterial tyrosine kinases and phosphatases.Phosphorylation is catalyzed by autophosphorylating adenosine triphosphate-dependent enzymes(bacterial tyrosine(BY) kinases) that are characterized by the presence of Walker motifs.The reverse reaction is catalyzed by three classes of enzymes:the eukaryotic-like phosphatases(PTPs) and dual-specific phosphatases;the low molecular weight protein-tyrosine phosphatases(LMW-PTPs);and the polymerase-histidinol phosphatases(PHP).Many BY kinases and tyrosine phosphatases can utilize host cell proteins as substrates,thereby contributing to bacterial pathogenicity.Bacterial tyrosine phosphorylation/dephosphorylation is also involved in biofilm formation and community development.The Porphyromonas gingivalis tyrosine phosphatase Ltp1 is involved in a restraint pathway that regulates heterotypic community development with Streptococcus gordonii.Ltp1 is upregulated by contact with S.gordonii and Ltp1 activity controls adhesin expression and levels of the interspecies signal AI-2.     

慢性鼻-鼻窦炎纤毛上皮细菌生物膜超微形态学观察

目的:观察慢性鼻-鼻窦炎(CRS)纤毛上皮细菌生物膜的超微形态学特点。方法:取4例行鼻内镜鼻窦手术的CRS患者中鼻甲黏膜,每个标本约4mm×4mm大小。经4%多聚甲醛固定24h、1%四氧化锇固定2h、乙醇梯度脱水、二氧化碳干燥、表面喷金镀膜后,用扫描电子显微镜观察标本超微形态。结果:4例标本均发现细菌生物膜的存在,生物膜主要形成于纤毛表面,细菌的鞭毛与纤毛缠绕;可见由多种细菌或细菌和真菌构成的混合感染。结论:细菌生物膜可以形成于CRS纤毛上皮上。     

The effects of rose bengal- and erythrosine-mediated photodynamic therapy on Candida albicans

The aim of this study was to evaluate the effects of photodynamic therapy (PDT) using rose bengal or erythrosine with light emitting diode (LED) on Candida albicans planktonic cultures and biofilms. Seven C. albicans clinical strains and one standard strain (ATCC 18804) were used. Planktonic cultures and biofilms of each C. albicans strain were submitted to the following experimental conditions: (a) treatment with rose bengal and LED (RB+L+); (b) treatment with erythrosine and LED (E+L+); and (c) control group, without LED irradiation or photosensitiser treatment (P-L-). After irradiation of the planktonic cultures and biofilms, the cultures were seeded onto Sabouraud dextrose agar (37 °C at 48 h) for counting of colony-forming units (CFU ml(-1) ) followed by posterior anova and Tukey's test analyses (P < 0.05). The biofilms were analysed using scanning electron microscopy (SEM). The results revealed a significant reduction of planktonic cultures (3.45 log(10) and 1.97 log(10) ) and of biofilms (<1 log(10) ) for cultures that were subjected to PDT mediated using either erythrosine or rose bengal, respectively. The SEM data revealed that the PDT was effective in reducing and destroying of C. albicans blastoconidia and hyphae. The results show that erythrosine- and rose bengal-mediated PDT with LED irradiation is effective in treating C. albicans.     

Addition of DNase improves the in vitro activity of antifungal drugs against Candida albicans biofilms

Cells within Candida albicans biofilms display decreased susceptibility to most clinically used antifungal agents. We recently demonstrated that extracellular DNA (eDNA) plays an important role in biofilm integrity, as a component of the biofilm matrix. This study aimed at gaining insights into the contributions of eDNA to C. albicans biofilms antifungal susceptibility by the investigation of the impact of the combined use of deoxyribonuclease I (DNase) and antifungals to treat biofilms. Candida albicans biofilms were formed using a simple and reproducible 96-well plate-based method. The activity of the combined use of 0.13 mg l(-1) DNase and antifungals was estimated using the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide (XTT) reduction assay and total viable counts. Herein, we report the improved efficacy of amphotericin B when in combination with DNase against C. albicans biofilms, as assessed using XTT readings and viable counts. Furthermore, although DNase increased the efficacy of caspofungin in the reduction of mitochondrial activity, no changes were observed in terms of culturable cells. Deoxyribonuclease I did not affect biofilm cells susceptibility to fluconazole. This work suggests that agents that target processes affecting the biofilm structural integrity may have potential use as adjuvants of a catheter-lock therapy.     

Decontamination efficacy of erbium:yttrium–aluminium–garnet and diode laser light on oral Candida albicans isolates of a 5-day in vitro biofilm model

The different forms of superficial and systemic candidiasis are often associated with biofilm formation on surfaces of host tissues or medical devices. The biofilm formation of Candida spp., in general, necessitates significantly increased amounts of antifungal agents for therapy. Often the therapeutic effect is doubtful. A 5-day biofilm model with oral Candida isolates was established according to Chandra et al. [39](J Dent Res 80:903–908, 2001) on glass and titanium surfaces and was modified by Sennhenn-Kirchner et al. [40](Z Zahnärztl Implantol 3:45–51, 2007) to investigate different aspects unanswered in the field of dentistry. In this model, the efficacy of erbium:yttrium–aluminium–garnet (Er:YAG) light (2940 nm, 100 mJ, 10 Hz, 300 μs pulsed mode applied for 80 s) and diode laser light (810 nm, 1 W, continuous wave mode applied for 20 s with four repetitions after 30 s pauses each) was evaluated and compared to untreated controls. The photometric evaluation of the samples was completed by observations on morphological changes of yeast cells grown in the biofilm. Compared to the untreated controls Candida cells grown in mature in vitro biofilms were significantly reduced by both wavelengths investigated. Comparison between the different methods of laser treatment additionally revealed a significantly greater effect of the Er:YAG over the diode laser. Scanning electron microscopy findings proved that the diode laser light was effective in direct contact mode. In contrast, in the areas without direct contact, the fungal cells were left almost unchanged. The Er:YAG laser damaged the fungal cells to a great extent wherever it was applied.     

Hydrophobic interactions in complexes of antimicrobial peptides with bacterial polysaccharides

Biofilms of Pseudomonas aeruginosa are responsible for chronic lung infections in cystic fibrosis patients, where they are characterized by overproduction of the exopolysaccharide alginate and are recalcitrant to treatment with conventional antibiotics. Cationic antimicrobial peptides (CAPs) are potential alternatives for the treatment of multi-drug-resistant P. aeruginosa. However, alginate in P. aeruginosa biofilms has been proposed to bind these peptides through hydrophobic interactions, consequently reducing their activity [Chan et al., J Biol Chem 2004; 279: 38749-38754]. Here we perform biophysical analyses of the interactions of alginate with a series of novel peptide antibiotics (alpha-CAPs) of prototypic sequence KK-AAAXAAAAAXAAWAAXAAA-KKKK (where X = Phe, Trp or Leu). The hydrophobic interaction interface in alginate was investigated by examining (i) the effects of polysaccharide composition with respect to D-mannuronate and L-guluronate content; (ii) glycan chain length; (iii) alpha-CAP Trp fluorescence; and (iv) 1-anilinonaphthalene-8-sulfonate fluorescence. The results show that, while M and G residues produce equivalent effects, hydrophobic interactions between alginate and alpha-CAPs require a minimal glycan chain length. Peptide interactions with alginate are deduced to be mediated by hydrophobic microdomains comprised of pyranosyl C-H groups that are inducible upon formation of alpha-CAP-alginate complexes due to charge neutralization between the two species.     

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。     

Implications of oral biofilms in medically at risk persons

There is the need to understand the composition of oral biofilms so that appropriate preventive and treatment regimens,including using appropriate antimicrobials,can be developed further.Additionally,when the systemic effects from specific microorganisms in oral biofilms are better understood,more targeted preventive treatment options may be recommended for persons at high risk for potential systemic diseases such as cardiovascular disease,and for aspiration pneumonia.Hence,the possible association between periodontopathic microorganisms,and also between cariogenic microorganisms in high caries risk persons,and systemic diseases requires further research involving metagenomic and large well-designed clinical studies.Effective preventive oral care is important for reducing potential systemic diseases.