Capillary electrophoretic method for Staphylococcus aureus detection by using a novel antimicrobial peptide

A novel peptide containing antimicrobial sequence and gelatinase cleavage sites was designed for Staphylococcus aureus detection. Since Staphylococcus aureus could secrete gelatinase, the fluorescein labeled peptide GKRWWKWWRRPLGVRGC could be recognized and cleaved. The obtained products were able to be analyzed by capillary electrophoresis with fluorescence detection. To explore the effect of Staphylococcus aureus concentration on enzyme digestion ability of peptide, Staphylococcus aureus with different concentrations were incubated with the peptide. Results indicated that capillary electrophoretic method was efficient for determining Staphylococcus aureus content. Compared with traditional approaches for Staphylococcus aureus detection, capillary electrophoresis possessed higher efficiency, enhanced sensitivity, and low sample consumption. Moreover, the proposed peptide also presented desirable antimicrobial activity. It suggested that the novel antimicrobial peptide used in this research opens a new path of detecting Staphylococcus aureus by capillary electrophoretic method.     

Biological Insights of Fluoroaryl-2,2′-Bichalcophene Compounds on Multi-Drug Resistant Staphylococcus aureus

Resistance of bacteria to multiple antibiotics is a significant health problem; hence, to continually respond to this challenge, different antibacterial agents must be constantly discovered. In this work, fluoroaryl-2,2′-bichalcophene derivatives were chemically synthesized and their biological activities were evaluated against Staphylococcus aureus (S. aureus). The impact of the investigated bichalcophene derivatives was studied on the ultrastructural level via scanning electron microscopy (SEM), molecular level via sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method and on the biofilm inhibition via the electrochemical biosensors. Arylbichalcophenes’ antibacterial activity against S. aureus was affected by the presence and location of fluorine atoms. The fluorobithiophene derivative MA-1156 displayed the best minimum inhibitory concentration (MIC) value of 16 µM among the tested fluoroarylbichalcophenes. Over a period of seven days, S. aureus did not develop any resistance against the tested fluoroarylbichalcophenes at higher concentrations. The impact of fluoroarylbichalcophenes was strong on S. aureus protein pattern showing high degrees of polymorphism. SEM micrographs of S. aureus cells treated with fluoroarylbichalcophenes displayed smaller cell-sizes, fewer numbers, arranged in a linear form and some of them were damaged when compared to the untreated cells. The bioelectrochemical measurements demonstrated the strong sensitivity of S. aureus cells to the tested fluoroarylbichalcophenes and an antibiofilm agent. Eventually, these fluoroarylbichalcophene compounds especially the MA-1156 could be recommended as effective antibacterial agents.     

中草药提取工艺优化及其体外抑菌的研究

对大黄、山楂、苦参、薄荷、黄芩和黄柏采用水煮法和乙醇回流法进行提取,用两倍稀释法测定金黄色葡萄球菌和大肠杆菌的体外最小抑菌浓度(MIC),研究不同中草药提取物的抑菌能力.结果表明:6种中草药对金黄色葡萄球菌呈现不同程度的抑菌作用,MIC值在1.56～50 mg/mL之间,其中大黄和黄芩的提取物对金黄色葡萄球菌的抑菌效果...     

Anti-microbial Activities of Protic Ionic Liquids Studied with Microcalorimetry Method

The anti-microbial activities of seven protic ionic liquids(ILs) against Escherichia coli and Staphylococcus aureus were studied by a micro-calorimetric method at 310 K.The bacterial growth rate constants were determined based on the bacterial growth power-time curves,andminimum biocidal concentrations were estimated.The results indicate that the protic ILs studied show inhibitory activities on the bacteria,implying a potential eco-toxicity to the microorganisms in the water system.Moreover,the inhibition e...     

Green Synthesized Silver Nanoparticles Immobilized on Activated Carbon Nanoparticles: Antibacterial Activity Enhancement Study and Its Application on Textiles Fabrics

This research aimed to enhance the antibacterial activity of silver nanoparticles (AgNPs) synthesized from silver nitrate (AgNO₃) using aloe vera extract. It was performed by means of incorporating AgNPs on an activated carbon nanoparticle (ACNPs) under ultrasonic agitation (40 kHz, 2 × 50 watt) for 30 min in an aqueous colloidal medium. The successful AgNPs synthesis was clarified with both Ultraviolet-Visible (UV-Vis) and Fourier Transform Infrared (FTIR) spectrophotometers. The successful AgNPs–ACNPs incorporation and its particle size analysis was performed using Transmission Electron Microscope (TEM). The brown color suspension generation and UV-Vis’s spectra maximum wavelength at around 480 nm confirmed the existence of AgNPs. The particle sizes of the produced AgNPs were about 5 to 10 nm in the majority number, which collectively surrounded the aloe vera extract secondary metabolites formed core-shell like nanostructure of 8.20 ± 2.05 nm in average size, while ACNPs themselves were about 20.10 ± 1.52 nm in average size formed particles cluster, and 48.00 ± 8.37 nm in average size as stacking of other particles. The antibacterial activity of the synthesized AgNPs and AgNPs-immobilized ACNPs was 57.58% and 63.64%, respectively (for E. coli); 61.25%, and 93.49%, respectively (for S. aureus). In addition, when the AgNPs-immobilized ACNPs material was coated on the cotton and polyester fabrics, the antibacterial activity of the materials changed, becoming 19.23% (cotton; E. coli), 31.73% (polyester; E. coli), 13.36% (cotton; S. aureus), 21.15% (polyester; S. aureus).     

Aptamer Immobilized Magnetoelastic Sensor for the Determination of Staphylococcus aureus

An aptamer-based magnetoelastic sensor for the determination of Staphylococcus aureus is reported. Aptamers specific to S. aureus were used to ensure specific and selective binding of bacteria on the sensor surface. The sensors were exposed to S. aureus concentrations of 1 × 10¹–1 × 10¹¹ colony forming units per milliliter, and the changes in resonance frequency were monitored. The sensitivity was higher for sensors with smaller physical dimensions. The biosensor with dimensions of 2 × 5 × 0.028 millimeters provided a linear dynamic range of 10¹–10¹¹ colony forming units per milliliter and a detection limit of 5 colony forming units per milliliter. The results also demonstrated that the magnetoelastic sensors determined the targeted pathogenic species with good selectivity. The method was employed to determine S. aureus in water, and the results were comparable to those obtained by plate-counting methods. The high sensitivity, selectivity, and stability of the aptamer provide a promising approach for the determination of pathogenic bacteria.     

Synthesis,characterization, and biological evaluation of Cu(II) complexes with the proton transfer salt of 2,6-pyridinedicarboxylic acid and 2-amino-4-methylpyridine

A proton transfer compound, (Hamp)⁺(Hdipic)^??·?1.5H₂O (1), and Cu(II) complexes, [Cu(dipic)(amp)(H₂O)]?·?[Cu(dipic)(amp)]?·?H₂O?·?CH₃COOH (2) and [Cu(dipic)(amp)Cu(dipic)(amp)(H₂O)Cu(dipic)(amp)(H₂O)]?·?3H₂O (3), have been synthesized from 2,6-pyridinedicarboxylic acid (H₂dipic) and 2-amino-4-methylpyridine (amp). They have been characterized by elemental, spectral (¹H-NMR, IR, and UV-Vis), and thermal analyses. In addition, magnetic measurements and single crystal X-ray diffraction have been applied to 2 and 3. The crystal structure of 2 consists of two independent and different cationic sites with Cu²⁺ ions. Cu1 is four-coordinate in a distorted square planar geometry and Cu2 is five-coordinate in a distorted square pyramid. Compound 3 has three independent and different cationic sites of Cu²⁺ ions. Cu1 is four-coordinate in a distorted square planar geometry and Cu2 and Cu3 have five-coordinate, distorted square-pyramidal sites. Inhibitory effects of 1, 2, and 3 have been studied and compared with starting compounds (amp and H₂dipic) on bacterial growth of Staphylococcus aureus and Escherichia coli cultures. Compounds 2 and 3 prevent bacterial growth although 1 has no effect. Compounds 2 and 3 are more effective than amp and H₂dipic, at similar concentrations on preventing bacterial growth for both organisms.     

N-methyl Benzimidazole Tethered Cholic Acid Amphiphiles Can Eradicate S. aureus-Mediated Biofilms and Wound Infections

Infections associated with Gram-positive bacteria like S. aureus pose a major threat as these bacteria can develop resistance and thereby limit the applications of antibiotics. Therefore, there is a need for new antibacterials to mitigate these infections. Bacterial membranes present an attractive therapeutic target as these membranes are anionic in nature and have a low chance of developing modifications in their physicochemical features. Antimicrobial peptides (AMPs) can disrupt the microbial membranes via electrostatic interactions, but the poor stability of AMPs halts their clinical translation. Here, we present the synthesis of eight N-methyl benzimidazole substituted cholic acid amphiphiles as antibacterial agents. We screened these novel heterocyclic cholic acid amphiphiles against different pathogens. Among the series, CABI-6 outperformed the other amphiphiles in terms of bactericidal activity against S. aureus. The membrane disruptive property of CABI-6 using a fluorescence-based assay has also been investigated, and it was inferred that CABI-6 can enhance the production of reactive oxygen species. We further demonstrated that CABI-6 can clear the pre-formed biofilms and can mitigate wound infection in murine models.     

针对不同来源金黄色葡萄球菌分离菌株的agr Ⅰ-Ⅳ分型初探

目的:金黄色葡萄球菌附属基因调节子(agr)位点是一个全面的群集感应系统并且控制着毒力因子的产生,本研究旨在针对不同来源的金黄色葡萄球菌分离菌株进行agr Ⅰ-Ⅳ基因分型研究.方法:根据金黄色葡萄球菌agrⅠ-Ⅳ基因组别类型的引物,对五种不同来源的169株金黄色葡萄球菌DNA模板进行多重PCR扩增,获得目的基因,以判断agr基因型.结果:169株分离菌株中,agrⅡ型的检出率为19%(32/169),agrⅢ型检出率为12%(20/169),agrⅣ型检出率为8%(14/169),五种不同来源的金黄色葡萄球菌均有检出agrⅡ型,均未检出agrⅠ型,并且都含有未能分型的agr阴性菌株.研究结果表明不同来源金黄色葡萄球菌分离菌株中agr Ⅰ-Ⅳ基因型的流行情况.该方法对于金黄色葡萄球菌菌株分子分型有一定的借鉴意义,也为金黄色葡萄球菌菌株分子流行病学调查奠定一定的基础.     

抗金黄色葡萄球菌活性炭的制备及工艺优化

本研究采用浸渍法制备了良好抗菌性能的载铜活性炭。通过单因素Plackett －Burman （ PB）设计和Box－Behnken Design （ BBD）中心组合设计法,考察各工艺条件对所制备的载铜活性炭抗菌率的影响,确定制备载铜活性炭的最佳工艺条件为活化时间2h,氯化铜浓度为0．07 mol· L－1,浸渍时间2h,活化温度700℃,浸渍比3时,抗菌率达100％。另外,采用傅立叶红外光谱仪、比表面积及孔径分析仪表征了活性炭的孔结构及表面官能团,通过傅立叶红外光谱仪分析得知其表面基团存在较多的含氧基团,通过孔径及表面积分析可知活性炭主要以微孔为主,也有不少数量的中孔存在。