Cadmium uptake by growing cells of gram-positive and gram-negative bacteria

The present study evaluates the effect of the cadmium (Cd2+) on the growth and protein synthesis of some Gram-positive (Staphylococcus aureus, Bacillus subtilis and Streptococcus faecium) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and the cadmium uptake by the same micro-organisms. The Gram-negative bacteria tested were less sensitive to metal ions than the Gram-positive, and P. aeruginosa was the most resistant. The Gram-negative bacteria were also able to accumulate higher amounts of cadmium during growth than the Gram-positive bacteria. The maximum values of specific metal uptake (microgram of Cd2+ incorporated per mg of protein) were: 0.52 for S. aureus, 0.65 for S. faecium, 0.79 for B. subtilis, 2.79 for E. coli and 24.15 for P. aeruginosa, respectively. The differences in the ability to accumulate metal found between Gram-negative and Gram-positive bacteria seems to account for different mechanisms of metal resistance.     

The adherence of Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli on cotton, polyester and their blends

The adherent behaviour of the Gram-positive Staphylococcus aureus and Staphylococcus epidermidis and the Gram-negative Escherichia coli on cotton, polyester and their blends through contact in aqueous suspensions was studied. Staphylococcus epidermidis was found to adhere to fabrics much more so than Staph. aureus. The adherence of both Staph. epidermidis and Staph. aureus to fabrics increased as the content of polyester fibres in the fabrics increased. The attachment of E. coli to all fabrics was very low and was not affected by the fibre contents. Total numbers of adherent bacteria on cotton and polyester fabrics were related directly to the concentrations of the bacterial suspensions. The extents of adherence, expressed by the percentage of adherent bacteria from the suspension, however, were independent of the concentration. The length of contact with bacteria was also found to affect the adherence of bacteria on fabrics studied.     

The adherence of Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli on cotton, polyester and their blends

The adherent behaviour of the Gram-positive Staphylococcus aureus and Staphylococcus epidermidis and the Gram-negative Escherichia coli on cotton, polyester and their blends through contact in aqueous suspensions was studied. Staphylococcus epidermidis was found to adhere to fabrics much more so than Staph. aureus. The adherence of both Staph. epidermidis and Staph. aureus to fabrics increased as the content of polyester fibres in the fabrics increased. The attachment of E. coli to all fabrics was very low and was not affected by the fibre contents. Total numbers of adherent bacteria on cotton and polyester fabrics were related directly to the concentrations of the bacterial suspensions. The extents of adherence, expressed by the percentage of adherent bacteria from the suspension, however, were independent of the concentration. The length of contact with bacteria was also found to affect the adherence of bacteria on fabrics studied.     

Composition and antimicrobial activity of the essential oil of Dicyclophora persica Boiss. from Iran

The chemical composition of the essential oil of Dicyclophora persica Boiss. was identified by GC and GC-MS analysis. The analysis of the oil resulted in the identification of forty-five components constituting 98.6% of the total oil. The main constituents were a-pinene (31.5%), (Z)-beta-ocimene (23.3%), p-cymene (6.7%) and (E)-beta-ocimene (5.4%). The antimicrobial activity of the oil was tested by the disk diffusion method against four Gram-positive (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis) and three Gram-negative (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) bacteria together with a fungus (Aspergillus niger). The oil showed strong inhibition activity toward all the tested microorganisms except for Pseudomonas aeruginosa.     

新型乳杆菌素产生菌的筛选及菌株特性的研究

从酸菜汁中分离出 2 4株乳酸杆菌 ,采用牛津杯定量扩散法筛选出 1株抑菌活性较高的乳酸杆菌 ,经鉴定为戊糖乳杆菌。排除乳酸对指示菌作用的干扰 ,该菌株的离心发酵液不仅对革兰氏阳性细菌有抑制作用 ,而且对大肠杆菌 (E .coli.) ,沙门氏菌 (Salmonellatyphi)等革兰氏阴性细菌也有一定的抑制作用     

Antimicrobial activity of Wedelia trilobata crude extracts.

A biological screening of activity against Gram-positive and Gram-negative bacteria, yeasts, and fungi of crude extracts from Wedelia trilobata is reported. The n-hexane extract showed antibacterial activity against Bacillus subtilis, Mycobacterium smegmatis, Staphylococcus aureus, and Staphylococcus epidermidis (Gram-positive bacteria); along with Proteus vulgaris, Pseudomonas aeruginosa, Salmonella group C, Salmonella paratyphi, and Shigella sonnei (Gram-negative bacteria). The ethyl acetate extract was active only against Salmonella group C; and the aqueous extract was inactive against the tested bacteria. None of the tested extracts showed biological activity against the yeasts (Candida albicans, Candida tropicalis, Rhodotorula rubra) or the fungi (Aspergillus flavus, Aspergillus niger, Mucor sp., Trichophyton rubrum).     

Antimicrobial activity of some Salvia species essential oils from Iran

The aerial parts of Salvia multicaulis, S. sclarea and S. verticillata were collected at full flowering stage. The essential oils were isolated by hydrodistillation and analyzed by combination of capillary GC and GC-MS. The in vitro antimicrobial activity of the essential oils were studied against eight Gram-positive and Gram-negative bacteria (Bacillus subtilis, Bacillus pumulis, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) and three fungi (Candida albicans, Saccharomyces cerevisiae and Aspergillus niger). The results of antibacterial activity tests of the essential oils according to the disc diffusion method and MIC values indicated that all the samples have moderate to high inhibitory activity against the tested bacteria except for P. aeruginosa which was totally resistant. In contrast to antibacterial activity, the oils exhibited no or slight antifungal property, in which only the oil of S. multicaulis showed weak activity against two tested yeasts, C. albicans and S. cerevisiae.     

重庆地区儿童2000年至2004年首位革兰阴性细菌和阳性细菌的耐药性监测

目的了解重庆地区儿童感染的分离至临床标本的首位革兰阴性细菌和阳性细菌对常用抗生素的耐药趋势,指导临床合理使用抗生素。方法常规方法分离、培养细菌,应用美国德灵公司WalkAway-40细菌鉴定仪对2000年至2004年我院细菌室分离至临床标本的首位革兰阴性细菌和阳性细菌共2854株进行细菌鉴定及药敏试验。结果2000年至2004年检出的首位革兰阴性细菌和阳性细菌分别为大肠埃希菌和金黄色葡萄球菌。2000年至2004年前5位革兰阴性菌5777株,革兰阳性菌1565株,其中大肠埃希菌2090株,金黄色葡萄球菌764株,分别占36.2%和48.8%;5年间大肠埃希菌对氨苄西林、头孢吡肟、头孢西丁、庆大霉素、亚胺培南、环丙沙星、头孢噻肟、头孢他啶的总耐药率分别为80.9%、37.5%、15.4%、54.0%、0.8%、34.0%、46.6%、46.2%;金黄色葡萄球菌对青霉素、红霉素、复方新诺明、万古霉素、阿莫西林/克拉维酸的总耐药率分别为95.6%、63.4%、5.8%、0%、11.0%。结论通过细菌耐药监测发现：大肠埃希菌对常用抗生素的总耐药率变化不大,金黄色葡萄球菌对常用抗生素的总耐药率有下降趋势,应引起临床医生重视。     

Synthesis and antibacterial activity of N-[2-(5-bromothiophen-2-yl)-2-oxoethyl] and N-[(2-5-bromothiophen-2-yl)-2-oximinoethyl] derivatives of piperazinyl quinolones

A series of N-[2-(5-bromothiophen-2-yl)-2-oxoethyl] and N-[2-(5-bromothiophen-2-yl)-2-oximinoethyl]derivatives of piperazinyl quinolones were synthesized and evaluated for antimicrobial activity against Gram-positive and Gram-negative microorganisms. Some of these derivatives exhibit comparable or better activity against Gram-positive bacteria, Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis, than ciprofloxacin, norfloxacin and enoxacine as reference drugs.     

Inhibitory and antimicrobial activities of OGTI and HV-BBI peptides, fragments and analogs derived from amphibian skin

A series of linear and cyclic fragments and analogs of two peptides (OGTI and HV-BBI) isolated from skin secretions of frogs were synthesized by the solid-phase method. Their inhibitory activity against several serine proteinases: bovine β-trypsin, bovine α-chymotypsin, human leukocyte elastase and cathepsin G from human neutrophils, was investigated together with evaluation of their antimicrobial activities against Gram-negative bacteria (Escherichia coli) and Gram-positive species isolated from patients (Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus sp., Streptococcus sp.). The cytotoxicity of the selected peptides toward an immortal human skin fibroblast cell line was also determined. Three peptides: HV-BBI, its truncated fragment HV-BBI(3-18) and its analog [Phe(8)]HV-BBI can be considered as bifunctional compounds with inhibitory as well as antibacterial properties. OGTI, although it did not display trypsin inhibitory activity as previously reported in the literature, exerted antimicrobial activity toward S. epidermidis. In addition, under our experimental conditions, this peptide did not show cytotoxicity.     

Preparation of chitosan-nylon-6 blended membranes containing silver ions as antibacterial materials

Chitosan-nylon-6 blended membranes were prepared by combining solvent evaporation and a phase inversion technique, and then used to chelate silver ions. Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli) were used to study the antibacterial properties of the membranes. Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) indicated hydrogen-bond interactions between chitosan and nylon-6. From the scanning electron microscopy (SEM) pictures, it was observed that with the increase of nylon-6 content, the blended membrane gradually became a material with porous morphology. After chelating silver ions, the tensile strength of the membranes increased. The antibacterial activity with the variation of chitosan content, the pH value and the concentration of the silver nitrate solution used to prepare Ag(+)-loaded membranes were investigated systematically. The results indicated that the chitosan-nylon-6 blended membranes with Ag(+) were antibacterial to both Gram-positive bacteria and Gram-negative bacteria. The antibacterial activity improved with the increased chitosan content due to the larger amount of silver ions loaded. The antibacterial property of the chitosan-nylon-6 blended membranes could be primarily attributed to the content of chitosan and silver ions as well as the surface morphology of the membranes.     

肛周脓肿患者病原菌结构和耐药性分析

摘要 目的：分析肛周脓肿患者的病原菌结构和其耐药情况,为临床抗菌药物的选择提供依据。方法：收集医院2019年1月~2020年12月期间收治的324例肛周脓肿患者的脓液标本,在实验室进行菌株的培养、鉴定及药敏试验,记录并分析结果。结果：324例患者均送检标本共分离出病原菌516株,其中革兰阴性菌421株,占81.59%;革兰阳性菌95株,占18.41%。421株革兰阴性菌中,以大肠埃希菌的检出率最高,其次是肺炎克雷伯菌;95株革兰阳性菌中金黄色葡萄球菌检出率最高。在革兰阴性菌中,大肠埃希菌整体耐药率较高,其对氨苄西林、头孢吡肟的耐药率均超过60.00%;肺炎克雷伯菌的耐药率相对较低,仅对头孢曲松、氨苄西林的耐药率超过30.00%。在革兰阳性菌中,金黄色葡萄球菌、表皮葡萄球菌和溶血葡萄球菌对氨苄青霉素、红霉素、环丙沙星和左氧氟沙星的耐药率均较高,超过50%,同时三种葡萄球菌均未检出万古霉素和利奈唑胺的耐药菌株。结论：肛周脓肿患者的病原菌以革兰阴性菌为主,大多为大肠埃希菌和肺炎克雷伯菌,病原菌对不同抗菌药物的耐药性差异较大,应根据药敏结果合理选用抗菌药物。     

Antimicrobial activity of essential oil and major constituents of Salvia chloroleuca

The aerial parts of Salvia chloroleuca were collected at full flowering stage at Shahrestanak (Tehran province of Iran). The essential oil was isolated by hydrodistillation and analyzed by combination of capillary GC and GC-MS. Thirty-four components were identified, representing 98.5% of the total oil. beta-Pinene (10.6%), alpha-pinene (9.0%), beta-caryophyllene (9.0%), 1,8-cineole (9.0%) and carvacrol (7.9%) were the main components. The in vitro antimicrobial activity of the essential oil of S. chloroleuca was studied against seven Gram-positive and Gram-negative bacteria (Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, S. epidermidis, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) and three fungi (Candida albicans, Saccharomyces cerevisiae and Aspergillus niger); the disc diffusion method and MIC values indicated that the oil exhibited moderate to high antimicrobial activity.     

Anti-infection silver nanoparticle immobilized biomaterials facilitated by argon plasma grafting technology

Many research groups have attained slow, persistent, continuous release of silver ions through careful experimental design using existing methods. Such methods effectively kill planktonic bacteria and therefore prevent surface adhesion of pathogens. However, the resultant modified coatings cannot provide long-term antibacterial efficacy due to sustained anti-microbial release. In this study, the anti-infection activity of AgNP immobilized biomaterials was evaluated, facilitated by argon plasma grafting technology and activated by bacterial colonization. The modified materials generated in this study showed excellent specificity and were active against both Gram-positive and Gram-negative biofilm forming bacteria, including methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli. The anti-infection biomaterials developed in this study demonstrate several attractive advantages in comparison to traditional anti-bacterial surfaces loaded with antibiotics or other types of antibacterial agents and include (1) broad spectrum of activity against antibiotic resistant bacteria, (2) the unlikelihood of bacterial resistance, (3) specificity, (4) biocompatibility, and (5) stability.     

Antibacterial action of a heat-stable form of L-amino acid oxidase isolated from king cobra (Ophiophagus hannah) venom

The major l-amino acid oxidase (LAAO, EC 1.4.3.2) of king cobra (Ophiophagus hannah) venom is known to be an unusual form of snake venom LAAO as it possesses unique structural features and unusual thermal stability. The antibacterial effects of king cobra venom LAAO were tested against several strains of clinical isolates including Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli using broth microdilution assay. For comparison, the antibacterial effects of several antibiotics (cefotaxime, kanamycin, tetracycline, vancomycin and penicillin) were also examined using the same conditions. King cobra venom LAAO was very effective in inhibiting the two Gram-positive bacteria (S. aureus and S. epidermidis) tested, with minimum inhibitory concentration (MIC) of 0.78μg/mL (0.006μM) and 1.56μg/mL (0.012μM) against S. aureus and S. epidermidis, respectively. The MICs are comparable to the MICs of the antibiotics tested, on a weight basis. However, the LAAO was only moderately effective against three Gram-negative bacteria tested (P. aeruginosa, K. pneumoniae and E. coli), with MIC ranges from 25 to 50μg/mL (0.2-0.4μM). Catalase at the concentration of 1mg/mL abolished the antibacterial effect of LAAO, indicating that the antibacterial effect of the enzyme involves generation of hydrogen peroxide. Binding studies indicated that king cobra venom LAAO binds strongly to the Gram-positive S. aureus and S. epidermidis, but less strongly to the Gram-negative E. coli and P. aeruginosa, indicating that specific binding to bacteria is important for the potent antibacterial activity of the enzyme.     

4种中药贯众原植物提取物的体外抗菌活性研究

用水提法和醇提法制备苏铁蕨（Brainea insighis）、华南紫萁（Osmunda vachellii）、狗脊蕨（Woodwardia japonica）和乌毛蕨（Blechnum orientale）的根状茎的提取液,应用纸片扩散法和试管二倍稀释法测定了各提取液对11种常见致病菌的抑菌圈、最低抑菌浓度（MIC）和最低杀菌浓度（MBC）。结果表明,各提取液（1g生药／mL）对表皮葡萄球菌、枯草芽孢杆菌、金黄色葡萄球菌及李斯特菌4种革兰氏阳性菌有明显抑制作用,对表皮葡萄球菌的抑制作用尤为明显,且醇提液的抑菌效果优于水提液;对大肠埃希氏菌等革兰氏阴性菌则无抑制作用。在4种贯众原植物中,苏铁蕨对革兰氏阳性菌的抑制活性最强。     

Syntheses and biological studies of novel spiropiperazinyl oxazolidinone antibacterial agents using a spirocyclic diene derived acylnitroso Diels-Alder reaction

Several novel oxazolidinone antibiotics with a spiropiperazinyl substituent at the 4'-position of the phenyl ring were synthesized through nitroso Diels-Alder chemistry and the in vitro antibacterial activities were evaluated against various Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and mycobacteria (Mycobacterium vaccae, Mycobacterium tuberculosis). Analogs (8a and 12) were active against selected drug resistant microbes, like methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) and had no mammalian toxicity in a Hep-2 cellular assay (CC(50) >100 μM).     

Anti-Helicobacter pylori activity of the methanolic extract of Geum iranicum and its main compounds

Geum iranicum Khatamsaz, belonging to the Rosaceae family, is an endemic plant of Iran. The methanol extract of the roots of this plant showed significant activity against one of the clinical isolates of Helicobacter pylori which was resistant to metronidazole. The aim of this study was the isolation and evaluation of the major compounds of G. iranicum effective against H. pylori. The compounds were isolated using various chromatographic methods and identified by spectroscopic data (1H and 13C NMR, HMQC, HMBC, EI-MS). An antimicrobial susceptibility test was performed employing the disk diffusion method against clinical isolates of H. pylori and a micro dilution method against several Gram-positive and Gram-negative bacteria; additionally the inhibition zone diameters (IZD) and minimum inhibitory concentrations (MIC) values were recorded. Nine compounds were isolated: two triterpenoids, uvaol and niga-ichigoside F1, three sterols, beta-sitosterol, beta-sitosteryl acetate, and beta-sitosteryl linoleate, one phenyl propanoid, eugenol, one phenolic glycoside, gein, one flavanol, (+)-catechin, and sucrose. The aqueous fraction, obtained by partitioning the MeOH extract with water and chloroform, was the most effective fraction of the extract against all clinical isolates of H. pylori. Further investigation of the isolated compounds showed that eugenol was effective against H. pylori but gein, diglycosidic eugenol, did not exhibit any activity against H. pylori. The subfraction D4 was the effective fraction which contained tannins. It appeared that tannins were probably the active compounds responsible for the anti-H. pylori activity of G. iranicum. The aqueous fraction showed a moderate inhibitory activity against both Gram-positive and Gram-negative bacteria. The MIC values indicated that Gram-positive bacteria including Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus subtilis are more susceptible than Gram-neagative bacteria including Escherichia coli and Pseudomonas aeruginosa.     

Bactericidal activities of rat defensins and synthetic rabbit defensins on Staphylococci, Klebsiella pneumoniae (Chedid, 277, and 8N3), Pseudomonas aeruginosa (mucoid and nonmucoid strains), Salmonella typhimurium (Ra, Rc, Rd, and Re of LPS mutants) and Escherichia coli.

Rat defensins were purified and tested for in vitro bactericidal assay against gram-positive and gram-negative bacteria. Staphylococcus aureus (209P, Cowan I, Smith diffuse and Smith compact) were resistant to defensins, whereas Staphylococcus epidermidis, Staphylococcus saprophyticus, Micrococcus lysodeikticus and Bacillus subtilis were less sensitive. Gram-negative bacteria, such as Pseudomonas aeruginosa (mucoid and K) and Klebsiella pneumoniae (Chedid, 277, and 8N3 which were heavily capsulated, moderately capsulated and noncapsulated, respectively) were all very sensitive to defensins and killed within 20 min. Escherichia coli was moderately sensitive and the rough mutants of lipopolysaccharide (LPS) of Salmonella typhimurium LT2, such as Ra, Rc, Rd, and Re were equally sensitive to defensins, being killed within 40 min. Lysozyme did not show any bactericidal activity except against M. lysodeikticus and B. subtilis, whereas it enhanced the bactericidal activity of defensins against P. aeruginosa, E. coli, and K. pneumoniae and suppressed the killing activity of defensins against S. typhimurium and S. aureus. With regard to the three synthetic rabbit defensins, NP1, NP4, and NP5, NP1 showed strong bactericidal activity against K. pneumoniae 277, comparable to that of rat defensins. Neither NP4 nor NP5 showed any bactericidal activity, while NP5 rather enhanced the bactericidal activity of NP1 against K. pneumoniae 277.     

Purification and characterization of an antibacterial factor from snail mucus

The antibacterial factor from the body surface of the African giant snail, Achatina fulica Férussac, was isolated by DEAE-Toyopearl 650M ion exchange chromatography. The isolated preparation exhibited highly positive antibacterial activity both for the Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus and for the Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, but it lost such activity when heated at 75 degrees C for 5 min. The antibacterial factor of the snail mucus was a glycoprotein whose molecular weight (MW) was about 160,000. It was composed of two subunits of MW 70,000-80,000.