Antibacterial effect of TiO2 modified with poly-amidoamine dendrimer – G3 on S. aureus and E. coli in aqueous solutions

This study investigated the bacterial removal using TiO2 nanoparticles (NPs) modified with poly-amidoamine dendrimer macromolecule (PAMAM, G3). The PAMAM G3/TiO2 (nanohybrid) was used to specify antibacterial properties via broth microdilution (MBC-Minimum Bactericidal Concentration and MIC-Minimum Inhibitory Concentration- determination), paper disc diffusion, and surface plate count methods. The nanohybrid was characterized via the different techniques. The effects of different factors including initial bacteria count, run time, solution pH, and the nanohybrid concentration were studied. The nanohybrid cytotoxicity was studied on AGS and MKN45 cells line by MTT assay. It was revealed that the nanohybrid was effective in intercepting both bacterial strains growth. The MIC value for S. aureus and E. coli were determined to be 4 and 2 μg/mL, respectively. The MBC value for both strains were calculated to be 32 μg/mL. The results showed removal efficiency of 100% for S. aureus and E. coli bacteria in optimum situation. The decrease in cell viability in the dosage of 32 μg/mL after 72 h treatment for AGS and MKN45 cells line were shown to be 6.2 and 4.6%, respectively. The nanohybrid was able to decrease the S. aureus and E. coli count in solution, which meets the drinking water criterions aligned with WHO guidelines.

Nanotebuconazole: Điều chế trong môi trường nước và khảo sát hiệu quả kháng nấm bệnh gây hại trên cây trồng

Tebuconazole được phân tán trong hỗn hợp polyethylene glycol (PEG) và nước theo một tỉ lệ xác định với sự hiện diện của dichloromethane (DCM). Hỗn hợp sau đó được làm bay hơi ở 40oC dưới áp suất 480 mbar để loại bỏ DCM và hình thành nanotebuconazole. Kích thước hạt nanotebuconazole được xác định trong khoảng 27 – 35 nm với kích thước trung bình là 29 nm bằng kĩ thuật tán xạ ánh sáng động (DLS) và kết quả nghiên cứu cho thấy tỉ lệ PEG:H2O 4:1 là thuận lợi nhất cho quá trình hình thành hạt nhũ nano. Các thử nghiệm in vitro bằng phương pháp MIC (minimum inhibitory concentration) chứng minh rằng dạng nanotebuconazole cho hiệu quả kháng khuẩn, kháng nấm mạnh gấp 2 lần dạng thương mại trên các chủng Ralstonia solanacearum, Fusarium ambrosium và Rhizoctonia solani và gấp 4 lần trên chủng Phytophthora capsici, với nồng độ ức chế tối thiểu lần lượt là 50 ppm và 25 ppm. Chế phẩm nanotebuconazole được đánh giá chất lượng đáp ứng đầy đủ tiêu chuẩn thuốc bảo vệ thực vật theo Tiêu chuẩn Việt Nam 9482:2012 (TCVN 9482:2012).

Tỷ lệ kháng colistin của vi khuẩn Klebsiella pneumoniae đa kháng và kháng carbapenem phân lập tại Bệnh viện Trung ương Quân đội 108 từ tháng 01/2020 đến tháng 09/2020

Mục tiêu: Xác định tỷ lệ kháng colistin của chủng vi khuẩn Klebsiella pneumoniae đa kháng và kháng carbapenem phân lập tại bệnh viện Trung ương Quân đội 108 giai đoạn từ tháng 01/2020 đến tháng 09/2020. Đối tượng và phương pháp: Tổng số 86 chủng vi khuẩn K. pneumoniae được phân lập từ các mẫu bệnh phẩm lâm sàng được định danh và kháng sinh đồ bằng hệ thống Vitek-2 compact. Tỷ lệ kháng với colistin 86 chủng K. pneumoniae đa kháng kháng nhóm carbapenem được xác định bằng phương pháp khoanh giấy khuếch tán trong canh thang Muller-Hinton có điều chỉnh cation (CBDE, colistin broth disk elution) và nồng độ ức chế tối thiểu (MIC, Minimum Inhibitory Concentration) được xác định tương ứng. Kết quả: Tỷ lệ vi khuẩn K. pneumoniae đa kháng kháng carbapenem là 20,05% (86/429). Trong đó, tỷ lệ phân bố các chủng đó tại các khoa: Khoa Hồi sức tích cực, Viện Truyền nhiễm và Khoa Ngoại tiêu hoá lần lượt là 35,0% (30/86), 17,0% (15/86), 8,0% (7/86). K. pneumoniae kháng carbapenem chủ yếu được phân lập từ bệnh phẩm hô hấp 55,81% (48/86), bệnh phẩm máu 20,93% (18/86), bệnh phẩm nước tiểu 12,79% (11/86), bệnh phẩm dịch 10,47% (9/86). Tỷ lệ kháng colistin (MIC ≥ 4mg/mL) của chủng vi khuẩn K. pneumoniae đa kháng và kháng carbapenem là 45,0% (39/86), ngoài ra có 15,0% (13/86) chủng tăng MIC colistin (1mg/mL < MIC ≤ 2mg/mL). Kết luận: Tình trạng vi khuẩn K. pneumoniae đa kháng, kháng carbapenem và colistin đã tăng cao trong bệnh viện, do đó cần có hướng dẫn sử dụng nhóm kháng sinh này tại bệnh viện, cũng như áp dụng các công cụ chẩn đoán phát hiện nhanh các chủng kháng thuốc.

Oxazinethione Derivatives as a Precursor to Pyrazolone and Pyrimidine Derivatives: Synthesis, Biological Activities, Molecular Modeling, ADME, and Molecular Dynamics Studies

In this study, we used oxazinethione as a perfect precursor to synthesize new pyrimidine and pyrazole derivatives with potent biological activities. Biological activities were determined for all compounds against A. flavus, E. coli, S. aureus, and F. moniliform. Compounds 3, 4a-b, and 5 exhibited higher activities toward A. flavus, E. coli, S. aureus, and F. moniliform; this was indicated through the MIC (minimum inhibitory concentration). At the same time, anticancer activities were determined through four cell lines, Ovcar-3, Hela, MCF-7, and LCC-MMk. The results obtained indicated that compound 5 was the most potent compound for both cell lines. Molecular docking was studied by the MOE (molecular operating environment). The in silico ADME of compounds 2 and 5 showed good pharmacokinetic properties. The present research strengthens the applicability of these compounds as encouraging anticancer and antibacterial drugs. Moreover, JAGUAR module MD simulations were carried out at about 100 ns. In addition, spectroscopic studies were carried out to establish the reactions of the synthesized structure derivatives.

Susceptibility in vitro of clinical Candida albicans isolates to the selected azoles

Candida spp. is the most prevalent cause of fungal infection worldwide, and their increasing resistance to anti-fungal agents, especially to azoles, has become problematic. The aim of this work was to establish the susceptibility to fluconazole, itraconazole, voriconazole and posaconazole of 50 clinical C. albicans isolates from hematooncological patients. This has been evaluated using the following parameters: MIC (Minimum Inhibitory Concentration), MIC50 (MIC required to inhibit the growth of 50% of organisms), as well as MIC90 (MIC required to inhibit the growth of 90% of organisms). Susceptibility of the studied clinical isolates to all azoles was high, being 86% for itraconazole, 90% for fluconazole and posaconazole and 92% for voriconazole. The resistance rates ranged from 8% (voriconazole), to 12% (itraconazole). The emergence of azole-resistant yeast strains creates a necessity to determine and monitor the sensitivity of the isolated Candida spp., including C. albicans, especially in patients predisposed to life-threating fungal invasive disease.

Rhizobium Leguminosarum: A Model Arsenic Resistant, Arsenite Oxidizing Bacterium Possessing Plant Growth Promoting Attributes

The threat of arsenic (As) pollution has become serious and leading to opt of low-cost microbial remediation strategies.Some bacteria have the ability to resist As. A group of rhizosphere bacteria have the ability to absorb arsenic. So these bacteria may be a good candidate for arsenic bioremediation from contaminated environment. Our present study of identifying suitable rhizobacterial strains led to the isolation of As-tolerant strains from arsenic pollutedrhizospheric soils of lentil in West Bengal, India.The isolated rhizobacterial strain LAR-7 had a high MIC (minimum inhibitory concentration) towards arsenate (260 mM) and arsenite (27.5 mM) and transformed 39% of arenite to arsenate under laboratory condition. Further, the strain LAR-7 had enormous plant growth-promoting characteristics (PGP), as categorized by efficient ability to solubilize phosphate, siderophore production, production of indole acetic acid-like molecules, ACC deaminase production, and nodule formation under As stressed condition. Based on 16S rRNA homology the LAR-7 was identified as Rhizobium leguminosarum andemerged as the most potent strain for As decontamination and plant growth promoter under the stress environment of As.

AKTIVITAS ANTIBAKTERI EKSTRAK BIJI JERUK SIAM (Citrus reticulata) PADA BAKTERI Escherichia coli

Antibacterial Activity of Citrus seed (Citrus reticulata) Extract on Escherichia coli Indonesian agriculture provides a resource of medicinal plants whose potential needs to be explored in order to benefit society. One of them is the use of Siam orange seeds (Citrus reticulata) which has the potential for the production of antibacterial compounds. This study aims to test the antibacterial activity of the ethanol and n-hexane extract of orange seeds. The extract was obtained through maceration techniques using ethanol and n-hexane as solvents. The antibacterial activity test of orange seeds against Escherichia coli used the paper disc diffusion method with nutrient agar (NA) media. The concentration of orange seed extract for the determination of MIC (Minimum Inhibitory Concentration) was 0.5, 2, 8, 10, 20 mg mL-1. The results showed that the ethanol and n-hexane extract of orange seeds had antibacterial activity against E. coli. However, the ethanol extract had a higher antibacterial effect than the n-hexane orange seed extract. From the results of this study, it is hoped that the waste of orange seeds will provide beneficial contribution for pharmaceutical development. Pertanian Indonesia memiliki sumber tanaman obat yang perlu digali potensinya agar bermanfaat bagi masyarakat. Salah satunya pemanfaatan biji jeruk siam (Citrus reticulata) yang berpotensi menghasilkan senyawa antibakteri. Penelitian ini bertujuan untuk menguji aktivitas antibakteri ekstrak etanol dan n-heksana biji jeruk. Ekstrak diperoleh melalui teknik maserasi menggunakan pelarut etanol dan n-heksana. Uji aktivitas antibakteri biji jeruk terhadap Escherichia coli menggunakan metode difusi paper disc dengan media nutrient agar (NA). Konsentrasi ekstrak biji jeruk untuk penentuan MIC (Minimum Inhibitory Concentration) adalah 0,5, 2, 8, 10, 20 mg mL-1. Hasil penelitian menunjukkan bahwa ekstrak etanol dan n-heksana biji jeruk memiliki aktivitas antibakteri terhadap E. coli. Namun, ekstrak etanol memiliki efek antibakteri yang lebih tinggi dibandingkan ekstrak biji jeruk n-heksana. Dari hasil penelitian ini, limbah biji jeruk diharapkan dapat memberikan kontribusi bermanfaat bagi pengembangan farmasi.

Effect of Selected Antibiotics on Biofilm Formed by Salmonella Enterica Serovars Typhi and Paratyphi

Salmonella enterica serovars Typhi and Paratyphi are the causative agents of typhoid and paratyphoid, respectively, in human. Salmonella is able to form biofilms whereby members are resistant and persistent in both host and nonhost environments. In the present study the effect of the antibiotics, Azithromycin, Imipenem, Ceftriaxone and Cefixime, on planktonic and biofilm phase clinical isolates of Salmonella enterica serovars Typhi (n = 30) and Paratyphi A (n= 07) was investigated. MIC (Minimum Inhibitory Concentration) and MBC (Minimum Bactericidal Concentration) of planktonic phase bacteria were determined and compared with MRC (Minimum Re-growth Concentration) and MBEC (Minimum Biofilm Eradication Concentration) of biofilm population. The present study indicates that, with the exception of Azithromycin, a considerably higher concentration is needed for all other antibiotics investigated to inhibit growth of test isolates in the biofilm phase. We conclude that the requirement of Azithromycin at sub-MIC concentration to inhibit/kill Salmonella in biofilm is of particular significance in that it can be employed for the eradication of Salmonella spp. biofilms. Bangladesh J Microbiol, Volume 37 Number 2 December 2020, pp 62-65

Antibacterial Activity of Honey Samples from Ukraine

The employment of natural substances such as beehive products with a preventive and therapeutic purpose has been a widespread custom since ancient times. In this investigation, the antibacterial activity of 41 honey samples from different Ukraine regions has been evaluated. For each honey, melissopalynological and physico-chemical analysis were performed in order to determine botanical origin, pH, glucose and fructose contents and free acidity. So, antibacterial activity against Staphylococcusaureus CCM 4223, Listeria monocytogenes ATCC 7644, Salmonella enterica serovar Typhimurium CCM 3807 and Escherichia coli ATCC 25922 was assessed through the determination of MIC (Minimum Inhibitory Concentration) and MBC (Minimum Bactericidal Concentration) values by the microdilutions method. The results show that the most susceptible bacterial strain was L. monocytogenes. Its growth was inhibited at a honey concentration ranging from 0.094 to 0.188 g/mL. The most resistant bacterial strain was S. aureus. As concerns MBC values, L. monocytogenes was the most susceptible bacteria, while S. aureus was the most resistant. Helianthus spp. honeys was the most effective against all tested bacterial strains, followed by Robinia spp. and multifloral honeys. Promising results for MIC tests have been found for Brassica spp.

Antibacterial Alkaloids and Polyketide Derivatives from the Deep Sea-Derived Fungus Penicillium cyclopium SD-413

Nine secondary metabolites (1–9), including two new polyketide derivatives 9-dehydroxysargassopenilline A (4) and 1,2-didehydropeaurantiogriseol E (5), along with seven known related secondary metabolites (1–3 and 6–9), were isolated and identified from the deep sea-derived fungus Penicilliumcyclopium SD-413. Their structures were elucidated on the basis of 1D/2D NMR spectroscopic and mass spectrometric analysis and the absolute configurations were determined by the combination of NOESY correlations and time-dependent density functional (TDDFT) ECD calculations. Compounds 1–9 inhibited some pathogenic bacteria including Escherichia coli, E. ictaluri, Edwardsiella tarda, Micrococcus luteus, Vibrio anguillarum, and V. harveyi, with MIC (minimum inhibitory concentration) values ranging from 4 to 32 μg/mL.