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Caries is a common dental problem brought on by factors like excessive sugar consumption, poor oral hygiene, and the presence of microorganisms in the mouth. This dental pathology is treated with a variety of filling materials, including tooth-colored direct resin dental composite (RDC), glass ionomer cement (GIC), and dental amalgam (also known as silver filling). RDC is the most preferred filling material in dental clinics due to its excellent esthetics and minimal tooth preparation, making it the need of the modern era. However, antimicrobial agents were added to this material in order to enhance its ability to prevent secondary caries. The antibacterial activity of RDC has been tested using a variety of methods, but testing protocols have been found to vary. Thusly, the point of this article is to examine the disparity in the strategy involved by specialists for testing the antibacterial properties of RDCs. [ABSTRACT FROM AUTHOR]

Caries is a common dental problem brought on by factors like excessive sugar consumption, poor oral hygiene, and the presence of microorganisms in the mouth. This dental pathology is treated with a variety of filling materials, including tooth-colored direct resin dental composite (RDC), glass ionomer cement (GIC), and dental amalgam (also known as silver filling). RDC is the most preferred filling material in dental clinics due to its excellent esthetics and minimal tooth preparation, making it the need of the modern era. However, antimicrobial agents were added to this material in order to enhance its ability to prevent secondary caries. The antibacterial activity of RDC has been tested using a variety of methods, but testing protocols have been found to vary. Thusly, the point of this article is to examine the disparity in the strategy involved by specialists for testing the antibacterial properties of RDCs.

In this study, 5% Nd3+ doped Cerium oxide (Ce0.95Nd0.05O2) was prepared by a modified solid-state reaction method. Crystallite size and lattice strain were determined from the Williamson-Hall (W-H) plot. The four distinct peaks in the photoluminescence (PL) spectra in the visible region signify the structural defects within the crystal lattice. Room temperature ferromagnetism (RTFM) was observed from the hysteresis loop, and the mathematical fitting of the hysteresis loop suggests ferromagnetic dominance (∼83%) in the magnetic response. The virgin M-H loop was fitted by the ferromagnetic Brillouin function, which suggests possible domain formation in the sample. The in vitro antibacterial activity of 5% Nd3+doped CeO2 was evaluated against two clinically isolated multidrug-resistant pathogenic bacterial strains, namely MLD 2 (Escherichia coli) and MLD 4 (Staphylococcus aureus), utilizing the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), disc agar diffusion (DAD) assays, etc. Notably, compared to the MLD 4 bacterial strain, the synthesized material revealed comparable better antibacterial results against the Gram-negative MLD 2 and in comparison, to the MLD 2 bacterial strain, a relatively higher concentration of the sample is required to completely eradicate the bacterial population of MLD 4. This implies that Ce0.95Nd0.05O2 can destroy the growth of the two tested bacterial strains. In the context of cytotoxicity, up to a certain concentration, the synthesized particle demonstrated no appreciable toxicity towards healthy PBMCs.

Nystatin is a polyene macrolide antifungal active which is used for the treatment of candidiasis and obtained from some species of Streptomycesbacteria. The present work describes the statistical suitability analysis for regular monitoring of the agar diffusion bioassay in a simple, inexpensive and time-saving process before potency determination. A balanced (symmetrical) two-dose parallel line assay model was applied using the agar well diffusion method for quantification of Nystatin in raw material and finished medicinal dosage form. The routine inspection methodology yielded good results and included calculations by the linear parallel model and by means of regression analysis and verified using analysis of variance (ANOVA). The assay is based on the inhibitory effect of Nystatin upon a standard strain as described in the United States Pharmacopeia (USP). The results of the post validation regular assays were treated statistically by ANOVA and the deviations (expressed as average ± standard deviation) from both raw and column totals were 0.702 ± 0.476 and 0.865 ± 0.468, respectively. The mean value of the variance ratio for regression and parallelism squares were 534.349 ± 212.546 and 0.596 ± 0.345, respectively. The study of Nystatin's ongoing analysis showed that the microbiological assay design is satisfactory with respect to the limiting values for the determination of the potency. The established balanced parallel line assay is reasonably stable and suitable and can be used for the regular drug analysis in routine quality control testing and the quantitation of Nystatin in pharmaceutical dosage form and raw material. Doi: 10.28991/SciMedJ-2021-0304-2 Full Text: PDF

Till nowadays microbiological assay is still widely used with several antibiotics that are composed of a mixture of related active compounds. However, obtaining a reasonably valid determination of the potency is dependent on the validity and the suitability of the assay design. The present work aimed to validate an assay design of an aminoglycoside antibiotic (Gentamicin Sulfate) using a two-dose Parallel Line Model agar diffusion assay in a large 8×8 rectangular plate. All preparatory procedures were done following United States Pharmacopeia and the Inhibition Zones were measured using a digital caliper to the nearest 0.01 mm. Analysis of variance of compendial requirements of regression and parallelism were found to be satisfactorily meeting the acceptance criteria. Specificity was achieved for the product under investigation with no detectable IZ that could be found for all components except the antibiotic. The validation method showed acceptable linearity of r2≥0.98. Accuracy and precision parameters showed RSD (%)

Introduction: Essential oils are secondary metabolites of aromatic plants and are used in phytotherapy to treat various diseases. In the present study, eight selected essential oils - ajwain oil (Trachyspermum ammi L.), fennel oil (Foeniculum vulgare Mill. subsp. vulgare var. vulgare), thyme oil chemotype (ct.) thymol (Thymus vulgaris L.), tea tree oil (Melaleuca alternifolia Cheel.), oregano oil (Origanum vulgare L.), mountain savory oil (Satureja montana L.), lemongrass oil (Cymbopogon citratus (DC.) Stapf.) and eucalyptus oil (Eucalyptus globulus Labill.) -were examined for their antibacterial effect against Pasteurella (P.) multocida and Mannheimia (M.) haemolytica isolates from deep nasopharyngeal swab samples of fattening calves using agar diffusion and microdilution. All eight essential oils were effective against the tested isolates. Lemongrass oil proved to be the most potent of all eight essential oils, while fennel oil was only weakly effective. Different antimicrobial effects were observed between the two research methods. The effectiveness of ajwain, thyme, oregano and mountain savory oils was comparable in agar diffusion. However, this could not be reproduced using the microdilution method. P. multocida was found to be more sensitive to all essential oils tested than M. haemolytica. This study shows that the tested essential oils have antimicrobial in-vitro effects on P. multocida and M. haemolytica isolates and that the examination method is associated with the test result.

Clove oil contains eugenol as an antibacterial. Meanwhile, products containing clove oil have been widely used as toothpaste and mouthwash. In this study, clove oil was formulated in the form of edible film because it is practical, easy to use, and could be used without water like other oral hygiene preparations. The edible film is a thin layer film made of consumable materials used as a carrier of antibacterial compounds. Clove oil edible film was then formulated with clove oil concentrations of 1%, 1.5%, and 2% and determined for its antimicrobial activity against Streptococcus mutans. Clove oil edible film preparations were evaluated under their physical properties, including friability, drying shrinkage, pH, thickness, and swelling ability. Antibacterial activity testing of clove oil edible film was conducted, employing the blood agar diffusion method against Streptococcus mutans. The physical evaluation of the clove oil edible film showed almost the same physical properties as the comparison (GF). Clove oil edible film test results revealed the greatest inhibition at F1 of 18.6 mm is more or less 0.577, F2 of 22.3 mm is more or less 2.081, and F3 of 25.3 mm is more or less 1.527. According to David and Stout, the inhibition activity of bacteria on F3 was categorized as a very strong group inhibition response. In addition, ANOVA test analysis results uncovered that the concentration of clove oil affected the inhibition of the Streptococcus mutans bacteria with a significance value of 0.000 (p less than 0.05). Also, Duncan's test exhibited that each concentration of clove oil had a significant difference in the inhibition of Streptococcus mutans bacteria.

[Display omitted] • Inhibition zone measurements from smartphone app were comparable values from regular callipers. • Bootstrapping method for measurement uncertainty evaluation was implemented in Python. • Both improvements were successfully applied to three different antibiotic substances. Usually, inhibition zone sizes in agar diffusion microbiological assay of antibiotics are measured using regular callipers. In this study, we proposed the use of a smartphone app for measuring inhibition zone sizes. The smartphone app allows for standardized measurements with a reference scale, which provides measured values comparable to those obtained using regular callipers. The main uncertainty source associated with antibiotic potency is inhibition zone size variability. Here, we suggest using the bootstrapping method, a resampling technique, to estimate measurement uncertainty without complex calculations. This simplifies the process and yields comparable results to the usual measurement uncertainty calculations. Both improvements were successfully applied to determine the potency of gentamicin, linezolid, and cefazolin. The results showed that smartphone-based measurements and the bootstrapping approach are valuable tools in agar diffusion microbiological assays. [ABSTRACT FROM AUTHOR]

Wool is considered to possibly exhibit antibacterial properties due to the ability of wool clothing to reduce the build-up of odor, which arises from the microbial activity of skin microbiota. Indeed, when tested with a widely used agar diffusion plate test method, even wool or other textiles not treated with any antimicrobial agent can be interpreted to show certain antibacterial effects due to the lack of growth under the specimen, as instructed in ISO 20645:2004 standard. Therefore, we analyzed in detail what happens to bacterial cells in contact with untreated wool and cotton fabric placed on inoculated agar plates by counting viable cells attached to the specimens after 1 and 24 h of contact. All wool and several cotton samples showed no growth under the specimen. Nevertheless, it was shown without a doubt that neither textile material kills bacteria or inhibits cell multiplication. A reasonable explanation is that bacterial cells firmly attach to wool fibers forming a biofilm during multiplication. When the specimen was lifted off the nutrient agar surface, the cells in the form of biofilm remained attached to the wool fibers, removing the biomass and resulting in a clear, no growth zone underneath it. By imaging the textile specimens with X-ray microtomography, we concluded that the degree of attachment could be dependent on surface topography. The results indicate that certain textiles, in this case, wool, could exhibit antibacterial properties by removing excess bacteria that grow on the textile/skin interface when taken off the body. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin de la Societe Vaudoise des Sciences Naturelles is the property of Societe Vaudoise des Sciences Naturelles and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nalca is an edible rhubarb-type plant from the southern of Chile; with studies focussing on petiole chemical and biological properties. This work evaluated for the first time the antibacterial capacities of three organs of nalca against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Petiole (P), root (R) and flower (F) ethanolic extracts at three different concentrations (25, 50, 100 mg/mL) were evaluated by means of agar diffusion assay and MIC. The result showed that antibacterial activities are bacteria and concentration dependent, with root having the highest antimicrobial activity of the organs plant studied. Compared to commercial antibiotics, nalca extracts show promising control over Ps. aeruginosa. The main polyphenolics of the extracts were identified by UPLC–MS/MS, observing for the first time caffeic, coumaric and gallic acids presence in all samples, with quercetin and rutin determined in petiole and flower extracts only. Our results contribute to better understanding of nalca attributes as potential source of antibacterial compounds to be used in nutraceutical, cosmetic and food industry. [ABSTRACT FROM AUTHOR]

The antagonistic effect of probiotics against oral pathogens merits exploration because these bacteria are beneficial to the host's health. The antimicrobial activity of two probiotic strains, Lactobacillus casei and Lactobacillus salivarius, as well as L. casei and L. salivarius combination (1:1), was investigated against Streptococcus mutans, Streptococcus sobrinus, Candida albicans, Candida glabrata and Candida tropicalis using agar-well diffusion, auto-aggregation and coaggregation assays. L. salivarius cell-free supernatant (CFS) alone exhibited greater inhibitory effect against Streptococci spp. compared to L. casei CFS alone and the combination. However, no inhibition was observed for Candida spp. L. salivarius alone exhibited significantly stronger auto-aggregation than L. casei alone (p = 0.05) and L. casei and L. salivarius combination. L. salivarius exhibited strong coaggregation ability with Candida spp., followed by Streptococci spp. while L. casei exhibited coaggregation only with Streptococci spp. However, L. casei and L. salivarius combination did not display any coaggregation with all strains. L. salivarius alone exhibited a stronger antagonistic effect on the tested organisms than L. casei alone or in combination. Based on the results, both probiotic strains showed good antimicrobial activities against oral pathogens and should be further studied for their human health benefits. [ABSTRACT FROM AUTHOR]

Background: the current research studies why it is effective using Anredera cordifolia, Psidium guajava, and Pogostemon cablin by the local community as a traditional medicine for diarrhea treatment caused by Escherichia coli bacteria. Objectives: We compared the inhibitor effectiveness of three leaf extracts against Escherichia coli; we also identified the anti-bacterial substances contained in leaf extracts. Methods: We determined the bacterial test activity using the "agar diffusion" method and the thin layer chromatography (TLC) as qualitative analysis for determining the anti-bacterial substances contained in the extract. Results: The Pogostemon cablin leaf extract contained terpenoids, phenolic, and flavonoids compound as bacterial inhibitors, and the comparison showed that Pogostemon cablin leaf extract had the greatest bacterial inhibition power. Conclusion: The antibiotic substances found in the leaf extracts of Anredera cordifolia, Psidium guajava, and Pogostemon cablin can be used as traditional medicine. The breakthrough was evidenced by the ability to inhibit Escherichia coli bacteria. This research shows that traditional medicine has ancient knowledge used by this paper. [ABSTRACT FROM AUTHOR]

Propolis is a substance produced by bees, especially Apis mellifera, from resins of plant shoots. It possesses numerous biological properties, such as antimicrobial and anti-inflammatory. Activities such as organic dairy farming show high demand for natural products with proprieties like those of propolis, since milk contamination and mastitis are major problems of the dairy industry. The objective of this study was to evaluate in vitro the antimicrobial activity of different concentrations of an ethanolic extract of propolis (EEP). Action of the EEP extracted from beehives in southern Brazil was tested against 13 different genera of bacterial agents that cause mastitis in dairy cattle. The experiment was carried out in the Laboratory of Parasitology and Microbiology at the Federal University of Pampa, Campus Dom Pedrito - RS, Brazil, during May and June 2016. Agar diffusion and microdilution plate methodologies were followed. Based on the results of the minimum inhibitory concentration test (MIC), the EEP had inhibitory activity on 100% of the bacteria tested at concentrations above 10% (w/v). These results show that propolis has antimicrobial potential against bacteria involved in the process of mastitis.

Green fabrication of nanoparticles has been established by means of a simple, economical and environmentally pleasant process. The present investigation describes the use of Myrtus communis plant leaves extract for the biosynthesis of the silver nanoparticle. The surface plasmon resonance peak at 435 nm, distinctive for silver, determined the synthesis of AgNP. The morphology of the particles was spherical and in size with an average diameter of ∼ 15 nm. Energy dispersive X-ray Fourier Transformed Infrared and X-ray diffraction techniques investigated the crystalline structure, purity and functional groups. The biogenic nanoparticles revealed the antibacterial efficacy against both gram-positive bacteria and gram-negative bacteria, suggesting its prospective applicability as an effective antibacterial agent.

Marine environment is the main source of natural bioactive products whose chemical-structural properties are not similar with other natural products of plants and other inland organisms. The present study was carried out to evaluate antibiotic properties of diethyl ether and methanol extracts of two marine species including starfish and carpet anemone. The samples of starfish and carpet anemone were collected from the Lark Island coasts. Extraction was done using diethyl ether and methanol solvents and antibiotic properties analysis on Escherichia coli and Bacillus subtilis were evaluated using agar diffusion method. Then tube dilution to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). According to the results, diethyl ether extract from carpet anemone had no inhibitory effect on E. coli tested bacteria. While, starfish methanol extract(40 mg/ml) and hadshowed a growth inhibitory effect on E. coli bacteriastarfish at a concentration of 40 mg/ml for E. coli bacteria. [M1] [32] The starfish methanol extract from starfish at concentration of (30 and 50 30 mg/ml) had an growth inhibitory effect onfor B. subtilis bacteria had an inhibitory effect on growth and at concentration of 50 mg/ml. The effect of Carpet anemone methanolic extract of (carpet anemone at 40 mg/ml) cause a growth inhibitory effect on for E. coli had an inhibitory effect on growth, but did not have a deleterious effect. starfish methanol extract [M3] [34] showed the highest growth inhibitory effect onThe diameter of the inhibition zone for B. subtilis and created a growth inhibitory circle zoonthe methanolic extract of the starfish showed of ( 12.1±0.8 mm diameter). [M5] [36] The results showed that the methanolic extract of the starfish has higher growth inhibitory effect on the two studied bacterial species. In conclusion, methanolic extracts of the starfish were effective in inhibiting the growth of Bacillus subtilis bacteria and methanolic extract of carpet anemone in inhibiting E. coli bacteria growth. methanolic extracts of the starfish and carpet anemone were effective in inhibiting the growth of B. subtilis and E. coli bacteria, respectively.[M7] [38]

Wool is considered to possibly exhibit antibacterial properties due to the ability of wool clothing to reduce the build-up of odor, which arises from the microbial activity of skin microbiota. Indeed, when tested with a widely used agar diffusion plate test method, even wool or other textiles not treated with any antimicrobial agent can be interpreted to show certain antibacterial effects due to the lack of growth under the specimen, as instructed in ISO 20645:2004 standard. Therefore, we analyzed in detail what happens to bacterial cells in contact with untreated wool and cotton fabric placed on inoculated agar plates by counting viable cells attached to the specimens after 1 and 24 h of contact. All wool and several cotton samples showed no growth under the specimen. Nevertheless, it was shown without a doubt that neither textile material kills bacteria or inhibits cell multiplication. A reasonable explanation is that bacterial cells firmly attach to wool fibers forming a biofilm during multiplication. When the specimen was lifted off the nutrient agar surface, the cells in the form of biofilm remained attached to the wool fibers, removing the biomass and resulting in a clear, no growth zone underneath it. By imaging the textile specimens with X-ray microtomography, we concluded that the degree of attachment could be dependent on surface topography. The results indicate that certain textiles, in this case, wool, could exhibit antibacterial properties by removing excess bacteria that grow on the textile/skin interface when taken off the body.

In this study, chemical compositions and in vitro antibacterial activities the components of essential oils and extracts of sage (Salvia officinalis L.), rosemary oil (Rosmarinus officinalis L.), lavandin (Lavandula x intermedia var. Super), and hyssop (Hyssopus officinalis L.) against fish pathogens: Gram-negative bacteria (Aeromonas caviae, Aeromonas hydrophila, Vibrio anguillarum, Yersinia ruckeri, Edwardsiella tarda, Pseudomonas aeruginosa) and Gram-positive bacteria (Lactococcus garvieae, Staphylococcus warneri, Vagacoccus salmoninarum) were investigated with Well Diffusion Agar assay. The composition of the essential oils and extracts were analyzed with GC/MS and HPLC, respectively. A total of 42 components in sage, 39 in rosemary, 44 in lavender, and 46 in hyssop were detected. As a result of this study, the sage and rosemary oils exhibited a broad-spectrum inhibitory effect (a strong antibacterial effect against Gram (+) and Gram (-) pathogens). Lavandin oil also showed a strong antibacterial effect against a majority of pathogens. The spectrum of inhibitory activity of hyssop oil was found narrower than other plant oils. In further studies, in vivo antibacterial effects of sage, rosemary and lavandin essential oils should be investigated. [ABSTRACT FROM AUTHOR]

This study investigates the bulb extracts of Crinum jagus for antimicrobial activities. The bulb samples were dried, ground and subjected to successive extraction using hexane, ethylacetate and methanol. The extracts were screened for activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi, Klebisidlae pneumonae, Candida albicans, Aspergillus niger, Penicillium notatum and Rhizopus stolonifer at concentrations between 6.25 and 200 mg/ml. Antimicrobial assays werecarried out using agar diffusion method. The Minimum Inhibitory Concentration (MIC) of the extracts was determined. The percentage yields obtained for the hexane, ethylacetate and methanol extracts of the bulbs are 0.28 %, 0.44% and 24.68 % respectively. Results showed that the methanolic extract had better antibacterial and antifungal activities than the other extracts. The methanol extract showed the highest antibacterial activity against S. aureus with a zone of inhibition of 28 mm at 200 mg/ml. Also, the methanol extract showed the highest antifungal activities against C. albicans, A. niger and P. notatum with a zone of inhibition of 20 mm at 200 mg/ml. The hexane and ethylacetate extracts had no activity against the microorganisms at 6.25 mg/ml.The methanol extract had the lowest Minimum Inhibitory Concentration (MIC) of 2.50 mg/ml against S. aureus, E. coli, B. subtilis, P. aeruginosa and S. typhi. The methanol extract could be a source of potent antimicrobial compounds. [ABSTRACT FROM AUTHOR]

When the quality of antibiotics and antibiotic dosage forms cannot be assessed with the help of chemical methods, one can use two variants of the agar diffusion test described in the State Pharmacopoeia XII, part 1 (General pharmacopoeial monograph 42-006807): the three-doses variant of the agar diffusion test and determination with the help of a standard curve. The method is based on directly proportional relationship between the size of test microorganisms inhibition zones and log concentration (dose) of the antibiotic in the solution placed onto agar bacterial medium. The size of the zone depends on a number of factors: sensitivity of the test microorganism to the antibiotic, homogeneity and density of the bacterial lawn, composition of the growth medium, amount of the growth medium placed on Petri dishes, chemical nature of the antibiotic, the dose of antibiotic used in the experiment. Laboratory employees who use this method to test the quality of antibiotics should have appropriate skills. The activity of the drug under testing is determined by comparing it to the established activity of the reference standard which should have compendial quality. Statistical methods are used to assess obtained results and confirm validity of test conditions. The precision of test results is confirmed by computing the 95% confidence interval, and the repeatability is supported by calculation of the relative standard deviation.

Plants have been used in ethno-medicine for ages in the treatment of various diseases. In the current study, the leaves of C. jagus are investigated for antimicrobial activities. The leaves were dried and extracted successively with hexane, ethylacetate and methanol. The concentrated extracts were screened for activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi, Klebisidlae pneumonae, Candida albicans, Aspergillus niger, Penicillium notatum and Rhizopus stolonifer at concentrations between 6.25 and 200 mg/ml using the agar diffusion method. The Minimum Inhibitory Concentration (MIC) was also determined. The percentage yields obtained were 0.92 %, 1.20 % and 25.2 % for the hexane, ethylacetate and methanol extracts respectively. The zones of inhibition of the organisms by the extracts generally increased with the concentrations. The methanol extract showed the best activity of the three extracts tested. The methanol extract had values ranging between 20 mm and 26 mm against the bacteria at 200 mg/ml. This extract also showed values between 18 mm and 20 mm against the fungi at 200 mg/ml. The lowest MICs values (of 2.5 mg/ml) were obtained against S. aureus, E. coli, B. subtilis and S. typhi. The polar constituents in the leaves of the plant are likely responsible for the antimicrobial properties observed. None of the extracts showed activity comparable to those of the standard drugs, however the methanol extract showed some potential as a source of antimicrobial compounds [ABSTRACT FROM AUTHOR]

Copyright of Ege Journal of Fisheries & Aquatic Sciences (EgeJFAS) / Su Ürünleri Dergisi is the property of Ege Journal of Fisheries & Aquatic Sciences (EgeJFAS) / Su Urunleri Dergisi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• O. polymorpha cat8Δ showed a higher resistance to BAC than wt in agar diffusion test. • Growth of wt, cat8Δ on xylose stimulated (p < 0.05) respiration in 100 mg/L BAC, compared to glucose. • Yeast immobilized on plastic units removed more (p < 0.05) BAC than a sterile carrier. Benzalkonium chloride (BAC) is highly abundant in wastewaters due to its wide application in household and industrial products. The aim of this research was to compare the resistance of two genetically related strains, Ogataea polymorpha (wild type) and O. polymorpha cat8 Δ (recombinant strain), to enhanced concentrations of BAC (≥ 100 mg/L) in terms of its appearance in wastewaters. Inhibition of the respiration activity of wt and cat8Δ by 100 mg/L and 300 mg/L BAC in a xylose-containing broth (4 g/L xylose) was dependent on the carbon source used for obtaining the yeast biomass through ethanol fermentation. The respiration activity of wt in a liquid broth was inhibited by BAC, while cat8Δ strain cells were characterized by similar amounts of CO 2 in the control and BAC-amended sets after 20 h of incubation and varied in range from 73.4 to 82.0 μgCO 2 /h for 108 CFU. In an agar diffusion assay, the resistance of both yeast strains to 12 μg BAC was dependent on the medium composition. BAC-removal activity was demonstrated for yeast cells immobilized on plastic units. [ABSTRACT FROM AUTHOR]

Green fabrication of nanoparticles has been established by means of a simple, economical and environmentally pleasant process. The present investigation describes the use of Myrtus communis plant leaves extract for the biosynthesis of the silver nanoparticle. The surface plasmon resonance peak at 435 nm, distinctive for silver, determined the synthesis of AgNP. The morphology of the particles was spherical and in size with an average diameter of ∼ 15 nm. Energy dispersive X-ray Fourier Transformed Infrared and X-ray diffraction techniques investigated the crystalline structure, purity and functional groups. The biogenic nanoparticles revealed the antibacterial efficacy against both gram-positive bacteria and gram-negative bacteria, suggesting its prospective applicability as an effective antibacterial agent. [ABSTRACT FROM AUTHOR]

The use of spices with antimicrobial properties has been very important in the food industry. The aim of this work was to study the antimicrobial effect of clove and cinnamon on the pathogens Salmonella spp., Escherichia coli and Staphylococcus aureus using the agar diffusion method, and double dilutions in broth. The extracts of cinnamon and clove studied under the agar diffusion method, caused no antimicrobial effect on Salmonella spp, while in its highest concentrations (100 y 150 mg/mL) if they showed an antimicrobial effect on E. coli and S. aureus, classified as sensitive. In the methodology of double dilutions in broth, it was determined that for S. aureus ATCC ® 29213TM the CMI and CMB were 512 μg/mL and 4096 μg/mL respectively and E. coli O157:H7 the CMI and CMB were 2048 μg/mL and 4096 μg/mL.

Three beach soils in Lagos, Nigeria were screened for the presence of antibiotic producing fungi against 8 test pathogenic bacteria & fungi. The physiochemical parameters of the soils were determined following standard procedures. Soil plate dilution method was employed for isolation of marine fungi and they were identified based on cultural and microscopic characteristics. Primary screening of isolated fungi for antibiotic potential was determined by perpendicular streak method against known pathogenic test organisms (Escherichia coli, Saphylococcus aureus, Klebsiella pnuemoniae, Pseudomonas aeruginosa, Candida albicans, Saccharomyces cerevisiae,Aspergillus niger and Aspergillus fumigatus). Further sreening of the product of secondary metabolism [antibiotic] of the active fungi was done by agar disc diffusion assay. The fungus with the highest secondary activity was subjected to molecular analysis for further identification. pH of beach soils was alkaline ranging from 7.6-8.0, while temperature and moisture were normal ranging from 26.333 ± 1.155a-30.333 ± 0.577aand 7.142 ± 1.497a-10.030 ± 3.130a respectively. A total of four fungal species of 2 different genera were isolated from the beaches ;Aspergillus niger,Aspergillus flavus,Penicillium purpurogenum and Penicillium islandicum. Both primary and secondary assays revealed only antibacterial activities against Staphylococcus aureus and Psedomonas aeruginosa with no effect on all test fungi. Highest antibacterial activity[28+0.2a] was exhibited by the fungus identified as Penicillium purpurogenum. Fungi from beaches in Lagos, Nigeria may be a promising source of antibacterial agent useful in the treatment of infections caused by S. aureus and P. aeruginosa. [ABSTRACT FROM AUTHOR]

• Formation of P. aeruginosa inhibition zone during tobramycin agar diffusion reflects biofilm growth. • Small aggregates in the inhibition zone are killed by tobramycin; larger aggregates survive and form the inhibition zone. • Bacteria at or beyond the stable inhibition zone border continue to form biofilm and produce an EPS matrix. • The inhibition zone misguides biofilm treatment that may not be eradicated with conventional tobramycin doses. Pseudomonas aeruginosa PAO1 (tobramycin MIC = 0.064 µg/mL) was used to perform agar diffusion tests employing tobramycin-containing tablets. Bacterial growth and formation of inhibition zones were studied by stereomicroscopy and by blotting with microscope slides and staining with methylene blue, Alcian blue and a fluorescent lectin for the P. aeruginosa PSL, which was studied by confocal laser scanning microscopy. Diffusion of tobramycin from the deposit was modelled using a 3D geometric version of Fick's second law of diffusion. The time-dependent gradual increase in the minimum biofilm eradication concentration (MBEC) was studied using a Calgary Biofilm Device. The early inhibition zone was visible after 5 h of incubation. The corresponding calculated tobramycin concentration at the border was 1.9 µg/mL, which increased to 3.2 µg/mL and 6.3 µg/mL after 7 h and 24 h, respectively. The inhibition zone increased to the stable final zone after 7 h of incubation. Bacterial growth and small aggregate formation (young biofilms) took place inside the inhibition zone until the small aggregates contained less than ca. 64 cells and production of polysaccharide matrix including PSL had begun; thereafter, the small bacterial aggregates were killed by tobramycin. Bacteria at the border of the stable inhibition zone and beyond continued to grow to a mature biofilm and produced large amount of polysaccharide-containing matrix. Formation of the inhibition zone during agar diffusion antimicrobial susceptibility testing is due to a switch from a planktonic to biofilm mode of growth and gives clinically important information about the increased antimicrobial tolerance of biofilms. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two microbiological and charge transfer complex formation spectrophotometric methods were successfully applied for determination of tioconazole in pure and different pharmaceutical dosage forms. • Different thermodynamic variables associated with the charge transfer complex were investigated and revealed the spontaneity and the exothermic nature of the complex formation. • The two methods were validated in accordance to ICH methodology. Two sensitive microbiological and charge transfer spectrophotometric methods have been developed for the quantitative determination of the antifungal drug, tioconazole, in its pure form and pharmaceutical preparations. The microbiological assay was based on the agar disk diffusion method by measuring the diameter of the inhibition zones related to different concentrations of tioconazole. The spectrophotometric method relied on charge transfer complex formation between tioconazole as an n-donor and chloranilic acid as a π-acceptor at room temperature. The formed complex was measured at λ max = 530 nm. The molar absorptivity and the formation constant of the formed complex were determined using different models, including the Benesi-Hildebrand, Foster-Hammick-Wardley, Scott, Pushkin-Varshney-Kamoonpuri, and Scatchard equations. Different thermodynamic parameters associated with the complex formation, including the free energy change (Δ G °), the standard enthalpy (Δ H °), and the standard entropy change (Δ S °), were evaluated. The two methods were validated in conformity with ICH-recommended guidelines and employed successfully for the quantification of tioconazole in both pure form and pharmaceutical formulations. [ABSTRACT FROM AUTHOR]

The present investigation aimed to utilize a direct wood disc diffusion method to study the influence of plane of cutting, cutting method, sterilization method, and origin of tree on the antimicrobial activity of wood material. Six oak wood trees (Quercus petraea) were collected from 3 different locations in France. They were cut into 4 mm thick slices with either transverse (RT), tangential (LT) or radial (LR) faces. Round discs (diameter 9.95 ± 0.1 mm) were cut from the slices via a laser machine or a manual punch machine, and were sterilized with gamma irradiation (25 kGy) or autoclaving (121 °C). The antimicrobial activity of wood was tested using a direct diffusion method against Staphylococcus aureus and Acinetobacter baumannii isolates. The zone of inhibition around the wooden disc was recorded following the recommendations used for antibiotics tests. The results showed that S. aureus was more susceptible than A. baumannii, to the chemicals that diffused from the wood. The transverse face discs exhibited higher antimicrobial activity. Samples that had been sterilized by autoclaving showed significantly (p < 0.05) lower antimicrobial activity, whereas the cutting method and origin of tree did not influence the antimicrobial activity of wood material. Therefore, the choice of sterilization method and cutting planes must be taken into account while studying and interpreting the antibacterial properties of wood material.

Introduction: Enterococcus faecalis are the most resistant and predominant microorganisms recovered from root canals of teeth where previous treatment has failed. Over the past decade, interest in drugs derived from medicinal plants has markedly increased. In dentistry, phytomedicines has been used as an anti-inflammatory, antibiotic, analgesic, sedative, and also as an endodontic irrigant. In endodontics, because of the cytotoxic reactions of most of the commercial intracanal medicaments and their inability to eliminate bacteria completely from dentinal tubules, the trend is shifting toward use of biologic medication extracted from natural plants. Aim: To compare the antimicrobial efficacy of newer irrigating agents which would probably be as effective or more and at the same time less irritating to the tissues than sodium hypochlorite (NaOCl). The objective of this study was to compare the antimicrobial activity of saturated and diluted (1:1) hydroalcoholic extract of Aloe vera, garlic, and 5% NaOCl against E. faecalis using the commonly used agar diffusion method. Results: Saturated hydroalcoholic extract of A. vera showed the highest zone of inhibition against E. faecalis. NaOCl, which is considered as gold standard, also showed higher zones of inhibition.

Intracanal medicaments play a vital role in disinfection of root canal system. The aim of this study was to evaluate intratubular penetration and fracture resistance of roots filled with micron- and nano-sized intracanal medicaments: calcium hydroxide (CH), nanocalcium hydroxide (NCH), chitosan (CS) and nanochitosan (NCS). Their antibacterial effect on E. faecalis was tested using agar diffusion method. NCH and NCS were prepared by precipitation method and ionic crosslinking respectively. NCH and NCS particles were spherical, with an average particle size of 102 ± 11.3 nm and 130 ± 17.6 nm respectively. The medicaments were filled in extracted human teeth. Depth of penetration of the medicaments into dentinal tubules at coronal (C), middle (M) and apical (A) thirds was measured. Fracture resistance of the teeth was evaluated after 1 week and 1-month intervals. NCH showed the highest depth of penetration (C ∼746.98 μm, M ∼700.30 μm, A ∼134.69 μm). CS showed the highest fracture resistance, whereas no significant difference was found between other medicaments, at both the time intervals. NCH (8.07 ± 0.06) and NCS (8.13 ± 0.06) showed significantly higher zone of inhibition than CH (7.7 ± 0.17) and CS (7.37 ± 0.15). Under the conditions of this study, it can be concluded that NCH and NCS can be used as potential intracanal medicaments. [ABSTRACT FROM AUTHOR]

The use of spices with antimicrobial properties has been very important in the food industry. The aim of this work was to study the antimicrobial effect of clove and cinnamon on the pathogens Salmonella spp., Escherichia coli and Staphylococcus aureus using the agar diffusion method, and double dilutions in broth. The extracts of cinnamon and clove studied under the agar diffusion method, caused no antimicrobial effect on Salmonella spp, while in its highest concentrations (100 y 150 mg/mL) if they showed an antimicrobial effect on E. coli and S. aureus, classified as sensitive. In the methodology of double dilutions in broth, it was determined that for S. aureus ATCC ® 29213™ the CMI and CMB were 512 μg/mL and 4096 μg/mL respectively and E. coli O157:H7 the CMI and CMB were 2048 μg/mL and 4096 μg/mL. [ABSTRACT FROM AUTHOR]

Schinus molle L. (aguaribay, aroeira-falsa, “molle”, family Anacardiaceae), a native of South America, produces an active antibacterial essential oil extracted from the leaves and fruits. This work reports a complete study of its chemical composition and determines the antibacterial activity of Schinus molle L. essential oil and its main components. The results showed that the crude extract essential oil has a potent antibacterial effect on Staphylococcus aureus ATCC 25923, a strong/moderate effect on Escherichia coli ATCC 25922 and moderate/weak one on Pseudomonas aeruginosa ATCC 27853.

Gramicidin, an antimicrobial peptide active against Gram positive bacteria, is commonly used in pharmaceutical preparations for topical use. Considering that only the turbidimetric method has been described in the literature, the present study sought to develop and validate an agar diffusion method for the dosage of gramicidin. The method was developed and validated using the Kocuria rhizophila ATCC 9341 as a test microorganism. Two designs were used: a 3x3 parallel-line model, and a 5x1 standard curve. The validation demonstrated that the method follows the linear model (r²= 0.994), presenting a significant regression between the zone diameter of growth inhibition and the logarithm of the concentration within the range of 5 to 25.3 µg/mL. The results obtained for both designs were precise, having a relative standard deviation (R.S.D.) for intra-day precision of 0.81 for the 3x3 assay and 1.90 for the 5x1 assay. For the inter-day precision, the R.S.D. was 1.35 for the 3x3 and 2.64 for the 5x1. The accuracy was verified and results confirmed to be accurate, having a tolerance interval of 95%, which lay within permitted limits and appropriate trueness. In addition, the method was considered selective, with limit of detection and upper and lower limits of quantification of 2.00, 5.00 and 25.3 µg/mL, respectively. No difference in precision between the designs used in the agar diffusion method was evident (p>0.05). The method proved to be appropriate for the microbiological dosage of the raw material gramicidin.A gramicidina, um peptídeo antimicrobiano ativo contra bactérias Gram positivo, é utilizada em preparações farmacêuticas de uso tópico. Neste trabalho procurou-se desenvolver e validar outro método para o doseamento de gramicidina tendo em vista que somente o método turbidimétrico é descrito. O método de difusão em ágar foi desenvolvido e validado utilizando como microrganismo teste Kocuria rhizophila ATCC 9341. Foram utilizados dois delineamentos: retas paralelas 3x3 e curva padrão 5x1. A validação demonstrou que o método segue o modelo linear (r²= 0,994) havendo regressão significativa entre o diâmetro dos halos de inibição e o logaritmo da concentração na faixa de 5,00 a 25,3 µg/mL. Os resultados obtidos por ambos os delineamentos foram precisos apresentando desvio padrão relativo (DPR) para precisão intra-dia de 0,81 para ensaio 3x3 e de 1,90 para ensaio 5x1. Para a precisão inter-dias o DPR foi de 1,35 para 3x3 e de 2,64 para 5x1. A exatidão foi verificada e os resultados foram exatos apresentando intervalo de tolerância a 95% dentro dos limites permitidos e veracidade adequada. O método foi seletivo com limites de detecção e quantificação inferior e superior iguais a 2,00, 5,00 e 25,3 µg/mL, respectivamente. Não foi observada diferença entre a precisão dos delineamentos empregados no método de difusão em ágar (p>0.05). O método se mostrou adequado para a dosagem microbiológica de gramicidina matéria-prima.

Background: Using plant crude extracts on the control of microbial agents is increasing, because of medicinal, antifungal, antibacterial and antioxidant properties of plant-based secondary metabolites. Objective: The present work was conducted to find out antifungal activity of peppermint and access to the best solvent to elicit antifungal metabolites from peppermint. Methods: Aerial parts of peppermint were dried and crude extracts were obtained using water, methanol, ethanol, acetone and chloroform. The antifungal activity of this plant was evaluated on mycellial growth of phytopathogenic fungi, Rhizoctonia solani, Fusarium oxysporum, Phytophthora dershleri and Bipolaris sorkiniana using two different methods, paper disc and agar diffusion. Results: The results of the tested solvents demonstrated that water is the best to elicit the inhibitory compounds from peppermint. Methanol and acetone extracts had little inhibitory effects on B. sorkiniana while ethanol and chloroform extracts could not elicit inhibitory compounds against all of tested fungi. The mycellial growth of F. oxysporum and B. sorkiniana was inhibited at the concentration of 2mg/paper disc while the other two fungi was affected at the concentration of 4 mg/paper disc. In agar diffusion method, aqueous extract completely supperesed the growth of P. dershleri and B. sorkiniana at 500 and 1000 ppm of the crude extract, respectively. However, the mycellial growth of R. solani, F. Oxysporum was not completely supperesed even at 2000 ppm. Conclusion: From these results it was concluded that peppermint possesses sufficient in vitro activity on the control of tested phytopathogenic fungi. Besides, it can be stated that water is the best solvent among the tested solvents for extracting the antifungal compounds from peppermint.

Se estudiaron 1193 aislamientos clínicos para estandarizar y evaluar un método de difusión con discos de fluconazol de lectura visual, que permita detectar levaduras sensibles al antifúngico. Las especies analizadas fueron: Candida albicans (n=584), Candida parapsilosis (n=196), Candida tropicalis (n=200), Candida glabrata (n=113), Candida krusei (n=50), Candida spp. y otras levaduras oportunistas (n=50). Los discos fueron manufacturados en el INEI-ANLIS "Dr. Carlos G. Malbrán". Se midieron los halos de inhibición del crecimiento producidos por fluconazol y la concentración inhibitoria mínima (CIM) por el método de referencia M27-A2 modificado por EUCAST. Se establecieron los valores de corte del método de difusión en: ≥16 mm para levaduras sensibles a fluconazol (CIM ≤ 8 µg/ml), entre 9 y 15 mm para sensibles dependientes de la dosis (CIM = 16-32 mg/ml) y ≤ 8 mm para resistentes (CIM ≥ 64 µg/ml). El método de difusión tuvo 94,7% de concordancia con el de referencia, con 0,2% de errores very major y 0,3% de errores major. La reproducibilidad inter e intralaboratorio fue muy buena. Para detectar aislamientos sensibles a fluconazol, este método resulta confiable y de bajo costo; sin embargo, es conveniente que los aislamientos con halos ≤ 15 mm sean reevaluados por el método de referencia.In order to standardize and evaluate a disk diffusion method with visual reading to detect in vitro fluconazole susceptibility of yeast, 1193 clinical isolates were tested. These included 584 Candida albicans, 196 Candida parapsilosis, 200 Candida tropicalis, 113 Candida glabrata, 50 Candida krusei and 50 Candida spp. and other opportunistic yeasts. The disks were manufactured in the INEI-ANLIS "Dr. Carlos G. Malbrán". The disk diffusion method results were compared to MIC results obtained by the reference CLSI M27-A2 broth microdilution method modified by EUCAST. The interpretative breakpoints for in vitro susceptibility testing of fluconazole were established at: zone diameter ≥ 16 mm for MIC ≤ 8 µg/ml (susceptible isolates), between 9 and 15 mm for MIC = 16-32 mg/ml (susceptible dose-dependent isolates), and ≤ 8 mm for MIC ≥ 64 µg/ml (resistant isolates). Overall agreement between the two methods was 94.7%, with 0.2% very major errors, and 0.3% major errors. Inter - and intralaboratory agreement was good. The disk diffusion method for drug susceptibility testing of Candida spp. isolates is inexpensive, reliable and reproducible. However, when the inhibition zone diameter is ≤ 15 mm, it is advisable to test the isolate by the reference microdilution method.

Objectives: This study aims to assess the potential of a mixture of three antibiotics (TreVitaMix, TVM) as an intracanal dressing to disinfect the outer root surface by applying a new in vitro model. Materials and methods: Fifty freshly extracted bovine roots were endodontically treated. Forty samples were then thoroughly scaled, mounted to petri dishes, gas sterilized, and randomly allocated to four groups ( n = 10/group) according to their intracanal medication: sterile saline (NaCl; control, A); the TVM carrier material alone, i.e., propylene glycol (PG; B); TVM (C); and calcium hydroxide (D). In an additional group (E), the cementum was not removed and TVM was placed. Petri dishes were filled with Fastidious Anaerobe Agar, inoculated with Fusobacterium nucleatum suspension and then anaerobically incubated during 48-h intervals at 37 °C up to 192 h. Inhibition zones around the roots were then measured after each incubation period (mm). Results: Only teeth inoculated with the TVM dressing showed inhibition at all time points, whereas the other treatments showed no peri-radicular growing inhibition. Presence of cementum had no negative effect on disinfection ( p = 0.9320). Conclusion: TVM was able to penetrate through the dentine and inhibit the bacterial growth of F. nucleatum up to 192 h. Clinical relevance: TVM might have the potential to sustainably disinfect the outer root surface in perio-endo lesions and serve as an adjunctive antimicrobial agent. [ABSTRACT FROM AUTHOR]