scholarly journals CHITOSAN NANOPARTICLES AS DRUG DELIVERY SYSTEM FOR CEPHALEXIN AND ITS ANTIMICROBIAL ACTIVITY AGAINST MULTIIDRUG RESISTENT BACTERIA

2019 ◽  
pp. 14-27 ◽  
Author(s):  
Mona Elassal ◽  
Nagwan El-Manofy
Keyword(s):  
Antimicrobial Activity ◽  
Electron Microscope ◽  
Mammalian Cells ◽  
Synergistic Effects ◽  
Drug Loading ◽  
Chitosan Nanoparticles ◽  
Clinical Isolates ◽  
Antibiofilm Activity ◽  
Diffusion Kinetic

Objective: The evolution of antimicrobial resistance is a universal obstacle that necessities the innovation of more effective and safe antimicrobial alternatives with synergistic properties. The purpose of this study was to investigate the possible improvement of cephalexin antimicrobial treatments by loading into chitosan-based nanoparticles, then evaluate their antibacterial and antibiofilm activities as well as determination of its cytotoxicity. Methods: Chitosan nanoparticles (CSNPs) were prepared by ionic gelation method. Parameters were studied to optimize the particle size of CSNPs including pH, stirring rate, homogenization and ultra-sonication time. Size was measured by transmission electron microscope (TEM) and Zeta sizer, morphology seen by scanning electron microscope (SEM). Entrapment efficiency, drug loading and drug content were calculated. Stability of both plain and loaded chitosan Nano-carriers, Drug release and Kinetics also compatibilities were studied. Antimicrobial activity of CSNPs and cephalexin loaded CSNPs were evaluated against 4 Gram-positive and 4 Gram-negative standard and clinical isolates by microdilution method, also assessment of antibiofilm activity of both formulas was investigated against two biofilm producers clinical isolates by tube assay in addition to determination of their cytotoxicity by MTT(3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Results: Chitosan nanoparticles and its loaded antibiotics proved compatible combination with small Zeta size, suitable Zeta potential, maximum EE% and drug-loading capacity, sustained controlled release properties followed diffusion kinetic model and six month stability studies. Cephalexin loaded CSNPs showed better antimicrobial activity than plain CSNPs. Synergistic effects were found against S. aureus (ATCC 25923), B. subtilis (ATCC 9372), S. epidermidis, E. faecalis, P. aeruginosa (ATCC 29853) in addition to two carbapenem resistant isolates k. pneumoniae and E. coli. Also cephalexin loaded CSNPs exhibited antibiofilm activity against E. faecalis clinical isolate. Even though, cephalexin loaded CSNPs exhibited significant antibacterial activity, it showed less toxicity against mammalian cells, it had IC50 equal to 231.893 and did not exhibit any cytotoxicity against the WI-38 fibroblast cells at concentration 23.4 µg/ml. Conclusion: Cephalexin loaded CSNPs possessed good stability and sustained release effect in addition to its antimicrobial, antibiofilm activities and reduced cytotoxicity.

scholarly journals Antibiofilm forming, antimicrobial activity and some biochemical properties of Vaccinium vitis idaea leaf and berry extracts on Staphylococcus aureus

2020 ◽  
Vol 28 (3) ◽  
pp. 238-242
Author(s):  
M. V. Kryvtsova ◽  
I. Salamon ◽  
J. Koscova ◽  
M. Y. Spivak
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Properties ◽  
Biochemical Properties ◽  
Bacterial Biofilm ◽  
Biologically Active ◽  
Clinical Isolates ◽  
Antibiofilm Activity ◽  
Leaf Extracts ◽  
Berry Extracts ◽  
Promising Source

Infections caused by Staphylococcus genus bacteria remain a relevant problem due to the high percentage of antibio­tic-resistant biofilm-forming strains of isolates of this genus. Herbs are a promising source for many biologically active compounds with antimicrobial properties. The aim of the research was to study the antimicrobial and antibiofilm formation activity of berry and leaf extracts of Vaccinium vitis-idaea L. upon clinical isolates of S. aureus, and the main biochemical properties of these extracts. For the purpose of analysis, we used S. aureus isolated from the mouth cavities and pharynx of human patients suffering from inflammatory diseases. The plants for the study were gathered in Pylypets, Mizhhiria rayon, Zakarpatska oblast (Transcarpathia). From Vaccinium vitis-idaea L., leaf and berry extracts were produced. To determine the chemical properties of the extracts, the following constituents were investigated: total tannin, flavonoids, total phenols, anthocyanins (by spectrophotometric method), and the total amount of vitamin C in berry extract (chromatographically). The antimicrobial activity was studied by diffusion-into-agar method and determination of minimum inhibitory concentrations. The antibiofilm activity of the extracts was tested in standard 96-well microtitration plates. The main chemical composition of ethyl extracts of Vaccinium vitis-idaea L. berries and leaves was identified. The level of tannins in leaf extracts was established to be higher than in fruit extracts (3.50% and 0.26% per 100 g of extract, respectively). It was shown that extracts of V. vitis-idaea berries and leaves demonstrate high antimicrobial activity against clinical isolates of S. aureus. Further it was established that leaf extracts had high ability to destroy the bacterial biofilm of S. aureus. Leaf extracts were also able to destroy the formed biofilm. Even in the 0.01% concentration, leaf extract inhibited the formation of the biofilm by 69.9% and caused the destruction of the formed biofilm by 62.5%. Thereby, the obtained results show good prospects for the use of V. vitis-idaea leaf extracts as an anti-staphylococcal remedy with antibiofilm forming properties.

Chemical composition, antimicrobial activity and synergistic effects with conventional antibiotics under clinical isolates by essential oil of Hymenaea rubriflora Ducke (FABACEAE)

2020 ◽  
pp. 1-5
Author(s):  
Graziela Claudia da Silva ◽  
Bruno Oliveira de Veras ◽  
Caio Rodrigo Dias de Assis ◽  
Daniela Maria do Amaral Ferraz Navarro ◽  
Dyana Leal Veras Diniz ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Chemical Composition ◽  
Essential Oil ◽  
Synergistic Effects ◽  
Clinical Isolates ◽  
Conventional Antibiotics

In vitro Antimicrobial, Antibiofilm and Antiquorum Sensing Activity of Indian Rhododendron (Melastoma malabathricum) against Clinical Isolates of Escherichia coli and Staphylococcus aureus

2021 ◽  
Author(s):  
Honeysmita Das ◽  
A.K. Samanta ◽  
Sanjeev Kumar ◽  
P. Roychoudhury ◽  
Kalyan Sarma ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Leaf Extract ◽  
Antimicrobial Agents ◽  
Clinical Isolates ◽  
Antibiofilm Activity ◽  
Zone Of Inhibition ◽  
Leaf Extracts ◽  
E Coli ◽  
Melastoma Malabathricum

Background: Development and persistence of multidrug resistant (MDR) bacteria is considered to be one of the biggest threats to public health worldwide. Development of new antimicrobial agents and alternatives to the conventional antimicrobial agents to control the menace of AMR is the need of the hour. Plants based products can be effectively explored as potential antimicrobial, antibiofilm and antiquorum sensing agents against major bacterial pathogens of human and animals. This present study was conducted to explore the antimicrobial, antibiofilm and antiquorum sensing activity of aqueous and methanol extracts of leaf, flower, fruit and stem of Melastoma malabathricum against clinical isolates of Staphylococcus aureus and Escherichia coli.Methods: E. coli and S. aureus were isolated and identified from diarrhoeic pigs and poultry and mastitic milk of cattle of Mizoram, respectively. Leaf, flower, fruit and stem of M. malabathricum were collected from Mizoram and extracted by methanol and aqueous solvents. The antimicrobial activity and MIC was determined by using well diffusion method and 96 wells microtiter plate method, respectively. Antibiofilm activity of plant extracts was determined in 96 well tissue culture plate. Antiquorum sensing activity was determined by disc diffusion method.Result: Methanol leaf extract exhibited antimicrobial activity against E. coli but not against S. aureus with 18 mm and 6 mm zone of inhibition at 200 mg/mL and 12.5 mg/mL, respectively. Methanol flower extract showed antimicrobial activity against S. aureus but not against E. coli with 14 mm and 6 mm zone of inhibitions at 200 mg/ml and 12.5 mg/mL, respectively. Similarly, the aqueous leaf extract showed antimicrobial activity against S. aureus but not against E. coli with 12 mm and 6 mm zone of inhibition at 200 mg/mL and 100 mg/mL, respectively. The MIC of M. malabathricum methanol leaf extract against E. coli was 3.125 mg/mL, whereas the MIC value of methanol flower and leaf extracts was 6.25 mg/mL against S. aureus. Antibiofilm activity of M. malabathricum methanol leaf, methanol flower and aqueous leaf extracts was recorded only against S. aureus isolates with maximum inhibition at 0.05 mg/mL concentration. Good antiquorum sensing activities was exhibited by the M. malabathricum methanol leaf, methanol flower and aqueous leaf extracts against S. aureus isolates at 200 mg/mL concentration.

scholarly journals Determination of Antimicrobial and Antibiofilm Activity of Combined LVX and AMP Impregnated in p(HEMA) Hydrogel

2021 ◽  
Vol 11 (18) ◽  
pp. 8345
Author(s):  
Ola Tarawneh ◽  
Wasan Alwahsh ◽  
Hassan Abul-Futouh ◽  
Luma A. Al-Samad ◽  
Lama Hamadneh ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Young’S Modulus ◽  
Antimicrobial Agents ◽  
Young's Modulus ◽  
Drug Combinations ◽  
Antibiofilm Activity ◽  
Hek 293 ◽  
Elongation Percentage ◽  
Tract Infections

Catheter-associated urinary tract infections (CAUTIs) are nosocomial infections, causing more than one million cases per year. CAUTIs cause serious health issues; in addition, the cost of replacement of the device constrains the employment of urological devices. Therefore, there is an urgent need to develop novel biomaterials for use in catheters. In this study, poly hydroxyethyl-methacrylate p(HEMA) and drugs-loaded p(HEMA) with ampicillin trihydrate (AMP), levofloxacin (LVX), and drug combinations were prepared using free radical polymerization. The characterization of the dried films included the determination of glass transition temperature (Tg), ultimate tensile strength, elongation percentage, and Young’s modulus. Formulation toxicity, antimicrobial activity, and biofilm-formation ability were tested. Decreases in Tg value, U.T.S., and Young’s modulus, and an increase in elongation percentage were observed in AMP-loaded p(HEMA). Different ratios of drug combinations increased the Tg values. The films exhibited a cell viability higher than 80% on HEK 293 cells. Antimicrobial activity increased when p(HEMA) was loaded with LVX or a combination of LVX and AMP. Biofilm-forming ability reduced after the addition of antimicrobial agents to the films. p(HEMA) impregnated with AMP, LVX, and drug combinations showed significantly increased antimicrobial activity and decreased biofilm-forming ability compared with p(HEMA), in addition to the effects on (HEMA) mechanical properties.

scholarly journals Antimicrobial, antibiofilm and biochemichal properties of Thymus vulgaris essential oil against clinical isolates of opportunistic infections

2019 ◽  
Vol 27 (3) ◽  
pp. 270-275 ◽  
Author(s):  
M. V. Kryvtsova ◽  
I. Salamon ◽  
J. Koscova ◽  
D. Bucko ◽  
M. Spivak
Keyword(s):  
Antimicrobial Activity ◽  
Essential Oil ◽  
Opportunistic Infections ◽  
Clinical Isolates ◽  
Thymus Vulgaris ◽  
Antibiofilm Activity ◽  
Diffusion Test ◽  
Antibiotic Resistant ◽  
Thyme Essential Oil ◽  
Agar Diffusion Test

Thyme belongs to a genus encompassing over 215 species of hardy perennial herbaceous plants and sub-shrubs, which are native to Europe, particularly around the Mediterranean. Thymus vulgaris L., or garden thyme, with narrow small leaves and clusters of tubular mauve flowers, is used mainly in cookery. Dried herb yields 1% and more essential oil, which is a pale yellowish-red liquid with a sweet, very aromatic odour. Thyme is widely used in the pharmaceutical industry and is a source of substances of antimicrobial effect upon antibiotic-resistant strains of microorganisms. The purpose of our work was to identify the biochemical and antimicrobial peculiarities of Th. vulgaris essential oil against clinical isolates of opportunistic microorganisms. The analysis of thyme essential oil was carried out using GC/MS analysis. The clinical isolates were isolated with the use of differentially diagnostic nutrient media. The antibiotic susceptibility was identified with the help of the disc-diffusion test. The sensitivity of microorganisms to plant extracts was determined by the agar diffusion test. The antibiofilm activity of the extracts was tested in standard 96-well microtitration plates. The GC/MS results confirm the earlier reports that the major volatile constituents obtained from the aerial parts of thyme species were thymol, γ-terpinene, p-cymene, 3-carene and carvacrol. After subjecting the selected essential oil to effective steam distillation, substantial contents of phenolic monoterpenoids were obtained – thymol (67.7%) and γ-terpinene (8.2%). The European Pharmacopoeia set quality standards for thyme essential oil, which dealt mainly with the % content (w/w) of the volatile phenols (expressed as thymol: 36.0–55.0%). Garden thyme essential oil has been found to show a high antimicrobial activity against antibiotic-resistant microorganism strains. The obtained results proved the wide spectrum of antibiotic activity of thyme essential oil. The highest antimicrobial activity was registered against the typical and clinic strains of S. aureus and microscopic Candida genus fungi. Garden thyme essential oil was ascertained to show high antibiofilm-forming activity against S. aureus. The antimicrobial and antibiofilm-forming activities of thyme essential oil against both bacterial pathogens of opportunistic infections and microscopic fungi have proven the good prospects for development of a broad-spectrum agent against opportunistic microbial associations based on this oil.

scholarly journals The New Probiotic Lactobacillus Plantarum Strain Isolated from Traditional Dairy Showed The Synergistic Effect on Aflatoxin B1 Detoxification Along with Nanochitosan Particles

2021 ◽  
Author(s):  
Neda Zamani ◽  
Abbas Akhavan Sepahi ◽  
Mohammad Reza Fazeli ◽  
Farid Shariatmadari
Keyword(s):  
Antimicrobial Activity ◽  
Synergistic Effect ◽  
Aflatoxin B1 ◽  
High Performance ◽  
Synergistic Effects ◽  
Chitosan Nanoparticles ◽  
Food Products ◽  
Enzyme Linked Immunosorbent Assay ◽  
Different Strains

Abstract Background: Reduction of aflatoxin toxins in food products is of great importance. Therefore, in the present study, the effects of new Lactobacillus plantarum strain isolated from dairy products as well as chitosan nanoparticles were studied on reducing of aflatoxin B1 (AFB1) toxicity in vitro.Methods: After collection and preparation yogurt, cheese, milk and whey products, lactic acid bacteria (LABs) were isolated and identified using biochemical and molecular methods. To measure probiotic activity, pH, bile and salt tolerance tests were used. Then, the antimicrobial activity of LABs against gastrointestinal pathogens was studied. Next, the cheese-separated strain (C1) was selected as the superior strain and antibiotic susceptibility testing was performed. Then, the effect of C1 isolate and chitosan nanoparticles on reducing aflatoxin B1 (AFB1) in the medium was studied by measuring AFB1 using the enzyme-linked immunosorbent assay (ELISA) and high performance liquid chromatography (HPLC).Results: The results of biochemical evaluations indicated the separation of different strains of Lactobacillus plantarum. Antimicrobial activity test showed extensive antimicrobial activity of C1 isolate. The results showed that this strain has good probiotic activities. This strain was shown to be resistant to the antibiotics erythromycin, fusidic acid, gentamicin, kanamycin, nalidixic acid, neomycin, ofloxacin and vancomycin. C1 strain together with chitosan nanoparticles had the ability to reduce AFB1 in the medium and when both were used simultaneously, and synergistic effect in reducing AFB1 from the medium was seen.Conclusion: In general, it was concluded that the new C1 L. plantarum strains together with chitosan nanoparticles could have synergistic effects in reducing AFB1 toxin in food products.

Synthesis and Antimicrobial Activity of Thiohydantoins Obtained from L-Amino Acids

2019 ◽  
Vol 17 (1) ◽  
pp. 94-102 ◽  
Author(s):  
Priscila Goes Camargo de Carvalho ◽  
Jhonatan Macedo Ribeiro ◽  
Renata Perugini Biasi Garbin ◽  
Gerson Nakazato ◽  
Sueli Fumie Yamada Ogatta ◽  
...  
Keyword(s):  
Amino Acids ◽  
Antimicrobial Activity ◽  
Antibacterial Activity ◽  
Mammalian Cells ◽  
Antimicrobial Agents ◽  
Ammonium Thiocyanate ◽  
Antibiofilm Activity ◽  
Bacterial Strains ◽  
Wide Range ◽  
Time Kill

Background: Thiohydantoins are an important class of heterocyclic compounds in drug discovery since they are related to a wide range of biological properties including antimicrobial activity. Objective: The objective of this study was to synthesize a series of thiohydantoins derived from Laminoacids and to evaluated their inhibitory effect on the growth of Gram-negative and Grampositive bacteria. Methods: All title compounds were synthetized by reaction of L-amino acids with thiourea or ammonium thiocyanate. Their antimicrobial activities were evaluated against bacterial strains by broth microdilution assays. The time-kill kinetics, the antibiofilm activity and the cytotoxicity to mammalian cells were determined for the compound that exhibited the best antimicrobial profile (1b). Results: Eleven thiohydantoins were readily obtained in good yields (52-95%). In general, thiohydantoins were more effective against Gram-positive bacteria. Compound 1b (derived from Lalanine) showed the best antibacterial activity against Staphylococcus epidermis ATCC 12228 and S. aureus BEC 9393 with MIC values of 940 and 1921 µM, respectively. The time-kill kinetics demonstrated time-dependent bactericidal effect in both strains for this derivative. Besides, 1b also exhibited antibacterial activity against biofilms of S. epidermidis ATCC 12228, leading to a 40% reduction in their metabolic activity compared to the untreated control. No cytotoxicity of 1b to mammalian cells was observed at MIC values. Conclusion: The data reported herein indicate relevant antimicrobial activity of thiohydantoins derived from L-aminoacid, mainly 1b, as potential pharmacophore to guide further chemical modification aiming at the search for new and improved antimicrobial agents.

scholarly journals Oleoresins and naturally occurring compounds of Copaifera genus as antibacterial and antivirulence agents against periodontal pathogens

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fariza Abrão ◽  
Thayná Souza Silva ◽  
Claudia L. Moura ◽  
Sérgio Ricardo Ambrósio ◽  
Rodrigo Cassio Sola Veneziani ◽  
...  
Keyword(s):  
Cysteine Protease ◽  
Biofilm Formation ◽  
Clinical Isolates ◽  
Antibiofilm Activity ◽  
Inhibition Assay ◽  
Periodontal Pathogens ◽  
Protease Inhibition ◽  
Periodontal Tissues ◽  
Causative Agents

AbstractInvasion of periodontal tissues by Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans can be associated with aggressive forms of periodontitis. Oleoresins from different copaifera species and their compounds display various pharmacological properties. The present study evaluates the antibacterial and antivirulence activity of oleoresins obtained from different copaifera species and of ten isolated compounds against two causative agents of periodontitis. The following assays were performed: determination of the minimum inhibitory concentration (MIC), determination of the minimum bactericidal concentration (MBC), and determination of the antibiofilm activity by inhibition of biofilm formation and biofilm eradication tests. The antivirulence activity was assessed by hemagglutination, P. gingivalis Arg-X and Lis-X cysteine protease inhibition assay, and A. actinomycetemcomitans leukotoxin inhibition assay. The MIC and MBC of the oleoresins and isolated compounds 1, 2, and 3 ranged from 1.59 to 50 μg/mL against P. gingivalis (ATCC 33277) and clinical isolates and from 6.25 to 400 μg/mL against A. actinomycetemcomitans (ATCC 43717) and clinical isolates. About the antibiofilm activity, the oleoresins and isolated compounds 1, 2, and 3 inhibited biofilm formation by at least 50% and eradicated pre-formed P. gingivalis and A. actinomycetemcomitans biofilms in the monospecies and multispecies modes. A promising activity concerning cysteine protease and leucotoxin inhibition was also evident. In addition, molecular docking analysis was performed. The investigated oleoresins and their compounds may play an important role in the search for novel sources of agents that can act against periodontal pathogens.

The Analysis of Dislocations Using a Symmetry Criterion

1972 ◽  
Vol 30 ◽  
pp. 660-661
Author(s):  
J. C. Ingram ◽  
P. R. Strutt ◽  
Wen-Shian Tzeng
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Displacement Field ◽  
Standard Technique ◽  
Residual Image ◽  
Symmetry Criterion

The invisibility criterion which is the standard technique for determining the nature of dislocations seen in the electron microscope can at times lead to erroneous results or at best cause confusion in many cases since the dislocation can still show a residual image if the term is non-zero, or if the edge and screw displacements are anisotropically coupled, or if the dislocation has a mixed character. The symmetry criterion discussed below can be used in conjunction with and in some cases supersede the invisibility criterion for obtaining a valid determination of the nature of the dislocation.The symmetry criterion is based upon the well-known fact that a dislocation, because of the symmetric nature of its displacement field, can show a symmetric image when the dislocation is correctly oriented with respect to the electron beam.

Feasibility of Molecular Structure Determination With a High Resolution Electron Microscope

1968 ◽  
Vol 26 ◽  
pp. 338-339
Author(s):  
T. A. Welton
Keyword(s):  
Electron Microscope ◽  
Substrate Surface ◽  
Helical Axis ◽  
Base Plane ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
High Degree ◽  
Degree Of Order ◽  
Purine Pyrimidine

An ultimate design goal for an improved electron microscope, aimed at biological applications, is the determination of the structure of complex bio-molecules. As a prototype of this class of problems, we propose to examine the possibility of reading DNA sequence by an imaginable instrument design. This problem ideally combines absolute importance and relative simplicity, in as much as the problem of enzyme structure seems to be a much more difficult one.The proposed technique involves the deposition on a thin graphite lamina of intact double helical DNA rods. If the structure can be maintained under vacuum conditions, we can then make use of the high degree of order to greatly reduce the work involved in discriminating between the four possible purine-pyrimidine arrangements in each base plane. The phosphorus atoms of the back bone form in projection (the helical axis being necessarily parallel to the substrate surface) two intertwined sinusoids. If these phosphorus atoms have been located up to a certain point on the molecule, we have available excellent information on the orientation of the base plane at that point, and can then locate in projection the key atoms for discrimination of the four alternatives.

Sign in / Sign up

Export Citation Format

Share Document