Antimicrobial and antiviral activities of an actinomycete (Streptomyces sp.) isolated from a Brazilian tropical forest soil

A promising producer of bioactive compounds isolated from a Brazilian tropical soil was tested for its range of antimicrobial activities. Strain 606, classified as Streptomyces sp., could not be identified up to species level, suggesting a possible new taxon. The supernatant and 10 extracts and fractions, obtained by extraction and chromatographic techniques, presented antimicrobial activity using antibiograms. The methanolic fraction was highly active against pathogenic bacteria, phytopathogenic fungi and the human pathogenic yeast Candida albicans. It also possessed high antiviral activity inhibiting the propagation of an acyclovir-resistant herpes simplex virus type 1 strain on HEp-2 cells at non-cytotoxic concentration. The strong cytotoxic effect suggests an antitumour action. This revised version was published online in August 2006 with corrections to the Cover Date.     

Structure–antimicrobial activity of some natural isocoumarins and their analogues

Three naturally occurring isocoumarins (paepalantine, paepalantine 9-O-beta-D-glucopyranoside and paepalantine 9-O-beta-D-allopyranosyl(1 --> 6) glucopyranoside) and two semi-synthetic analogues, 9,10-acylated compound and 9-OH-10-methylated compound, structurally similar to paepalantine, were evaluated for antimicrobial activity using a spectrophotometric microdilution technique. The paepalantine was active against S. aureus, S. epidermidis, and E. faecalis while the other four compounds proved ineffective against all microorganisms tested at concentrations of 500 microg/ml. Variations in phenolic substitution at OH-9 and/or OH-10 in the paepalantine molecule resulted in compounds without antimicrobial activity. A combination of structural features, two phenolic groups as cathecolic system, forms an oxygenated system arrangement that may reflect the potentially antimicrobial properties of paepalantine.     

Coordination polymers of Ln(III): Synthesis, characterization, catalytic and antimicrobial aspects

Coordination polymers of HEAP-ED with La(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III) and Dy(III) metal ions have been synthesized and characterized by elemental analyses, electronic spectra, magnetic susceptibilities, FTIR, NMR, scanning electronic microscopy (SEM) and thermogravimetric analyses. Catalytic activity of selected coordination polymers was examined for pharmaceutical important organic synthesis. Antimicrobial activity of isolated Ln(III) coordination polymers against Escherichia coli, Bacillus subtilis, Staphylococcus aureus (bacteria) and Saccharomyces cerevisiae (yeast) were measured. It was observed from the study that the Ln(III) coordination polymers acted as an efficient and effective catalysts and antimicrobial agents.     

Confronting the challenges of discovery of novel antibacterial agents

Bacterial resistance is inevitable and is a growing concern. It can be addressed only by discovery and development of new agents. However the discovery and development of new antibacterial agents are at an all time low. This article broadly examines the historical as well as current status of antibacterial discovery and provides some perspective as how to address some of the challenges.     

Morphology of the granular hemocytes of the Japanese horseshoe crabTachypleus tridentatus and immunocytochemical localization of clotting factors and antimicrobial substances

Summary The structure of hemocytes in the normal state and during blood coagulation, and the intracellular localization of three clotting factors and two antimicrobial factors were examined in the Japanese horseshoe crabTachypleus tridentatus. Two types of hemocytes were found in the circulating blood: non-granular and granular hemocytes. The latter contained numerous dense granules classed into two major types: L- and D-granules. The L-granules were larger (up to 1.5 m in diameter) and less electron-dense than the D-granules (less than 0.6 m in diameter). The L-granules contained three clotting factors and one antimicrobial factor, whereas the D-granules exclusively contained the other antimicrobial factor. After treatment with endotoxin, the L-granules were released more rapidly than the D-granules, although almost all granules were finally exocytosed. The granular hemocyte possessed a single Golgi complex; possible precursor granules of L-granules and D-granules contained tubular and condensed dense material, respectively. These data are discussed in relation to the self-defense mechanisms of the horseshoe crab.     

Antimicrobial susceptibility of non-O1 Vibrio cholerae isolated from wastewater stabilization ponds in Marrakesh,Morocco

The 365 strains of Vibrio cholerae, isolated in Marrakesh from raw sewage and stabilization pond effluent, were all identified as non-O1 Vibrio cholerae. When tested for their susceptibilities to ampicillin, amoxicillin, cephalothin, streptomycin, novobiocin, chloramphenicol, nalidixic acid and trimethoprim-sulphamethoxazole, 13% of the strains from raw sewage and 20% of those from stabilization pond effluent were found to be resistant to one or more of the antibiotics. There were no significant differences, in terms of drug resistance, between isolates from the new sewage and those from the ponds' effluent.The authors are with the Université Cadi Ayyad, Faculté des Sciences Semialia, Département de Biologie, Laboratoire de Microbiologie, BP S/15, Marrakesh, Morocco     

Antimicrobial activity of lipoprotein particles containing apolipoprotein Al

Human plasmain vitro inhibits the growth of coagulase negative staphylococci,S. epidermidis, which may be pathogenic in the immunocompromised host. To determine the antimicrobial components, serum was fractionated by column chromatography, which revealed that elution areas where lipoproteins can be yielded had high antimicrobial activity againstS. epidermidis. Therefore, lipoprotein fractions, including very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL), were separated by ultracentrifugation and incubated withS. epidermidis. All 3 lipoprotein fractions suppressed bacterial growth within the first 3 h but VLDL enhanced bacterial growth after 9 h of incubation compared with the control. HDL, however, inhibited bacterial growth throughout 21 h of incubation.To confirm these results, serum from healthy volunteers was separated by ion exchange column chromatography and again by HPLC to purify the antimicrobial fraction. In the protein analysis with gradient polyacrylamide-SDS gel, apolipoprotein Al (apo Al), which is a major apolipoprotein of HDL, was detected in the antimicrobial fraction. Therefore, this fraction was loaded onto an immunoaffinity column coupled with the anti-apo Al monoclonal antibody (Mab). Unbound fraction had no antimicrobial activity, but anti-S. epidermidis activity was recovered from the bound fraction which consisted mainly of apo Al, All and apo C in protein composition.These results indicated that the antimicrobial activity was associated with the apo Al-containing lipoprotein particles (HDL). This property of HDL may directly affect bacterial growth and promote the self-defense mechanisms of normal and immunocompromised individuals.     

Green synthesis of zinc oxide nanoparticles using Anoectochilus elatus,and their biomedical applications

Zinc and its derivatives requirement increased to enhance human immunity against the different pandemics, including covid-19. Green synthesis is an emerging field of research. Zinc oxide (ZnO) nanoparticles have been prepared from Anoectochilus elatus and characterized using absorption, vibrational and electron microscope analysis. They were carried for antibacterial, inflammatory control tendency, and potential antioxidant activities. The brine shrimp lethal assay tested the biologically derived nanomaterial toxicity and the lethal concentration (LC₅₀) is 599.79 µg/ml. The inhibition against the important disease-causing pathogens was measured against four-gram negative, gram-positive bacteria and two fungus pathogens. The nanomaterial exposed inhibition zone for gram-positive bacteria between 17 mm and 25 mm. The inhibition zone against gram-negative bacteria exists between 19 mm and 24 mm. The anti-inflammatory activity was assessed by inhibition of protein denaturation and protease inhibitory activity using nanomaterial. The antioxidant activity was examined using four assays for the therapeutic activities. The average size range of 60–80 nm nanoparticles has prepared and exposed the good biological activity between 50 µg/ml and 100 µg/ml. The comparative results of anti-inflammatory and antioxidant assay results with standards such as Aspirin and vitamin C exposed that two to three times higher concentrations are required for the fifty percent of inhibitions. The prepared low-cost nanoparticle has exhibited excellent biological activity without any side effects and may enhance immunity.     

Silver nanostructures prepared via novel green approach as an effective platform for biological and environmental applications

Silver nanoparticles play a significant role in biomedical sciences due to their unique properties allowing for their use as an effective sensing and remediation platform Herein, the green synthesis of silver nanostructures (Ag NSs), prepared via aqueous extract of waste Brassica oleracea leaves in the presence of silver nitrate solution (10^-4 M), is reported. The Ag NSs are fully characterized and their efficacy with respect to 4-nitrophenol reduction, glucose sensing, and microbes is determined. Visually, the color of silver nitrate containing solution altered from colorless to yellowish, then reddish grey, confirming the formation of Ag NSs. HRTEM and SEAD studies revealed the Ag NSs to have different morphologies (triangular, rod-shaped, hexagonal, etc., within a size range of 20–40 nm) with face-centered cubic (fcc) crystal structure. The Ag NSs possess high efficacy for nitrophenol reduction (<11 min and degradation efficiency of 98.2%), glucose sensing (LOD: 5.83 µM), and antimicrobial activity (E. coli and B. subtilis with clearance zones of 18.3 and 14 mm, respectively). Thus, the current study alludes towards the development of a cost-effective, sustainable, and efficient three-in-one platform for biomedical and environmental applications.     

陕西食源性沙门氏菌耐药及相关基因

【目的】研究食源性沙门氏菌对常用抗生素的药敏性及相关耐药基因,更好的了解耐药性的产生和传播途径,确保食品安全。【方法】使用the Clinical and Laboratory Standards Institute推荐的琼脂稀释法测定沙门氏菌的药敏性,PCR和基因序列测定方法确定耐药沙门氏菌中整合子及其携带的耐药基因、与头孢菌素抗性相关的基因、沙门氏菌基因岛及与氟喹诺酮类抗生素耐药相关的基因突变。【结果】359株沙门氏菌中,67%的菌株对磺胺甲恶唑产生抗性,对甲氧苄啶/磺胺甲恶唑、四环素、卡那霉素、萘啶酮酸、氨苄西林、阿莫西林/克拉维酸、链霉素、氯霉素和庆大霉素、环丙沙星、头孢曲松、头孢西丁和头孢哌酮的耐药率分别为58%、56%、37%、35%、33%、32%、29%、26%、21%、16%、9%和8%。284株耐药菌中,79%的菌株可抗至少1种抗生素,25.9%可抗10种以上抗生素,2.5%可抗14种抗生素。耐药的Ⅰ类整合子以1.4kb最为常见,携带的耐药基因有aadA1、aadA2、aadA5、tetR、blaPSE-1、blaDHA-1、blaVEB-1、dhfrⅠ、dhfrⅤ、dhfrⅦ和dhfr17等。62株耐头孢曲松和/或头孢哌酮的沙门氏菌中,blaTEM和blaCMY-2基因的检出率分别为51.6%和56.5%。13.6%的沙门氏菌中检出了沙门氏菌基因岛。35株耐氟喹诺酮类抗生素的沙门氏菌的gyrA、parC和parE基因中共检出68个点突变,gyrA基因中常见突变为Ser83Phe、Ser83Tyr、Asp87Gly和Asp87Asn,parC基因中为Ser80Arg。parE基因中检出了Lys441Ile、Lys428Gln、Asp494Asn、Lys428Gln和Gly442Ser突变,这些点突变均为首次在食源性沙门氏菌中检出。【结论】陕西食源性沙门氏菌耐药状况严重,整合子、沙门氏菌基因岛和β-内酰胺酶编码基因的存在及解旋酶和拓扑异构酶基因突变是导致沙门氏菌耐药的重要机制。