Variable Antibacterial Activity Research Articles

Antibacterial Activities and Life Cycle Stages of Asparagopsis armata: Implications of the Metabolome and Microbiome.

The red alga Asparagopsis armata is a species with a haplodiplophasic life cycle alternating between morphologically distinct stages. The species is known for its various biological activities linked to the production of halogenated compounds, which are described as having several roles for the algae such as the control of epiphytic bacterial communities. Several studies have reported differences in targeted halogenated compounds (using gas chromatography-mass spectrometry analysis (GC-MS)) and antibacterial activities between the tetrasporophyte and the gametophyte stages. To enlarge this picture, we analysed the metabolome (using liquid chromatography-mass spectrometry (LC-MS)), the antibacterial activity and the bacterial communities associated with several stages of the life cycle of A. armata: gametophytes, tetrasporophytes and female gametophytes with developed cystocarps. Our results revealed that the relative abundance of several halogenated molecules including dibromoacetic acid and some more halogenated molecules fluctuated depending on the different stages of the algae. The antibacterial activity of the tetrasporophyte extract was significantly higher than that of the extracts of the other two stages. Several highly halogenated compounds, which discriminate algal stages, were identified as candidate molecules responsible for the observed variation in antibacterial activity. The tetrasporophyte also harboured a significantly higher specific bacterial diversity, which is associated with a different bacterial community composition than the other two stages. This study provides elements that could help in understanding the processes that take place throughout the life cycle of A. armata with different potential energy investments between the development of reproductive elements, the production of halogenated molecules and the dynamics of bacterial communities.

Nanoparticle surface coatings produce distinct antibacterial effects that are consistent across diverse bacterial species.

Nanoparticles have been proposed as tunable delivery vehicles for targeted treatments and, in some cases, the active therapeutic agents themselves. Despite the promise of such customizable impacts, little evidence exists to support these claims in the realm of antibiotics. Exploration of the silver and copper nanoparticle antibacterial impacts have been reported with inconsistent results. Here, we investigate the physical, chemical, and bacterial properties of silver and copper core particles stabilized with commonly used surface coatings, namely, polyvinylpyrrolidone (PVP, to confer a neutrally charged surface), cetrimonium bromide (CTAB, positively charged surface), citrate (Cit, negatively charged surface for silver nanoparticles), and ascorbic acid (AA, negatively charged surface for copper nanoparticles. The impacts of these potential antibacterial nanoparticles are measured against three bacterial species spanning deep divisions in the bacterial tree of life and include Escherichia coli, Staphylococcus aureus, and Sphingobacterium multivorum. Varying dose, core composition, surface coating, and bacterial species revealed that nanoparticle surfaces accounted for most of the variation in antibacterial activity. In all experiments, dose produced a linear inhibitory effect. Surprisingly, bacterial species reacted similarly regardless of evolutionary relatedness. There is a high degree of consistency, effectiveness, and efficacy among PVP silver and copper nanoparticle. These findings have implications for the intentional use of nanotechnology in environmental systems.

Identification and characterization of probiotics isolated from indigenous chicken (Gallus domesticus) of Nepal.

Excessive and irrational use of antibiotics as growth promoters in poultry has been one of key factors contributing to increased emergence of antibiotics resistant bacteria. Several alternatives for antibiotic growth promoters are being sought, and the search for effective probiotics to be used as feed additives is amongst the promising ones. Our study aimed to isolate and test potential probiotics bacteria from cloacal swabs of various indigenous chicken (Gallus domesticus) breeds from rural outskirts of the Kathmandu valley (Nepal). Selective isolation of probiotics was conducted by micro-aerophilic enrichment of sample in MRS Broth at 37°C, followed by culturing on MRS agar supplemented with 5 g/L of CaCO3. Isolated bacterial colonies producing transparent halo were selected as potential lactic acid bacteria (LAB), and tested for their antibacterial activity, phenotypic and biochemical characteristics, acidic yield, and tolerance to acid and bile. A total of 90 potential LAB were isolated from cloacal samples collected from 41 free-ranging chickens of indigenous breeds. Of these, 52 LAB isolates (57%) showed variable antibacterial activity to at least one bacterial pathogen. Of 52 LAB, 46 isolates fulfilled phenotypic and biochemical criteria of Lactobacillus spp. Of these, 37 isolates produced varying percentage yields of lactic acid, 27 isolates showed survival at pH 3.0, and 17 isolates showed survival tolerances in the presence of 0.3% and 0.5% bile salts for 24 hours. Phylogenetic analysis of 16S rDNA sequencing of LAB isolates fulfilling in vitro probiotics properties showed that 3 isolates had genetic identity of 99.38% with Lactobacillus plantarum, while one isolate was genetically similar (99.85%) with the clade of L. reuteri, L. antri and L. panis. Our study identified four Lactobacillus spp. strains having potential probiotics properties. Further investigations are needed to evaluate these isolates to be used as poultry probiotics feed supplement.

Synthesis of 1,2,3-triazole-thymol derivatives as potential antimicrobial agents

BackgroundThymol as a natural biological template can be modified chemically since the hydroxyl group makes it a candidate for structural modification. Thus, this study incorporated the triazole moiety on thymol and the chlorination of thymol moiety to help improve its biological potency. Materials and methodsA series of ten 1,2,3-triazole-thymol derivatives 1–10 were synthesized from thymol, by a click reaction between O-propargyl terminal alkyne of thymol and its chlorothymol with benzyl azide and substituted benzyl azides. Their structures were confirmed by spectroscopic methods (1H-NMR, 13C-NMR, IR, GC-MS-EI/CI and LC-ESI-QTOF-MS). The Well diffusion method using Müeller-Hinton agar plates was used to demonstrate the antimicrobial activities of the synthesized triazole-thymol derivatives on selected bacterial strains; Escherichia coli ATCC 25922, Staphylococcus aureus ATCC25923, Methicillin resistant S. aureus (MRSA), Pseudomonas aeruginosa ATCC 29853, E. coli ESBL, Klebsiella pneumoniae NCTC 13438 and Meropenem Resistant E. coli. ResultsAll the synthesized triazole-thymol derivatives showed significant but variable antibacterial activity against the seven medically important bacterial strains tested. The compound 4-((4-chloro-2-isopropyl-5-methylphenoxy)methyl)-1-(2-nitrobenzyl)-1H-1,2,3triazole (9) demonstrated a higher antibacterial activity with a mean zone of inhibition (38.7 mm) compared with ampicillin as the positive control which gave a zone size of 30.0 mm. In addition, the compound showed a three-fold potency than the parent compound, thymol (11.0 mm) against MRSA at a concentration of 100 μg/ml. ConclusionThese results provide additional evidence of the exploitation of natural products like thymol as leads for drug development against medically important bacterial pathogens.

BIOLOGICAL ACTIVITY OF ESSENTIAL SAGE OIL

Essential sage oil (ESO) was isolated from dry leaves by steam distillation with Neo-Clevenger apparatus. The chemical analysis of the ESO consisted in the assessment of the total polyphenolic content (Folin-Ciocâlteu method) and of the radical scavenging activity with DPPH. The antioxidant activity was measured using two standard compounds: gallic acid and ascorbic acid. Phenolic content of essential oil of S. officinalis was significant (15.465 mg GAE/g oil) and antioxidant activity was high. Antibacterial activity of essential sage oil was evaluated against Gram positive and Gram-negative bacterial strains isolated from clinical specimens. The sage oil showed significant but variable antibacterial activity with inhibition zones ranging from 4 mm to 9.5.mm. The effect was stronger on Gram positive (Enterococcus, Staplylococcus) than Gram negative bacteria (Escherichia sp, Proteus sp, Klebsiella sp).

Physicochemical Characterization and Biological Properties of Pine Honey Produced across Greece.

Pine honey is a honeydew honey produced in the East Mediterranean region (Greece and Turkey) from the secretions of the plant sucking insect Marchalina hellenica (Gennadius) (Coccoidea: Marchalini-dae) feeding on living parts of Pinus species. Nowadays, honeydew honey has attracted great attention due to its biological activities. The aim of this study was to study unifloral pine honey samples produced in Greece regarding their physicochemical parameters and antioxidant and antibacterial activity against five nosocomial and foodborne pathogens. These honeys showed physicochemical and microscopic characteristics within the legal limits, except for diastase activity, a parameter known to be highly variable, depending on various factors. Substantially higher levels of H2O2 were estimated compared to other types of honeydew honey, whereas protein content was similar. The total phenolic content was 451.38 ± 120.38 mg GAE/kg and antiradical activity ranged from 42.43 to 79.33%, while FRAP values (1.87 to 9.43 mmol Fe+2/kg) were in general higher than those reported in the literature. Various correlations could be identified among these parameters. This is the first attempt to investigate in depth the antibacterial activity of pine honey from Greece and correlate it with honey quality parameters. All tested honeys exerted variable but significant antibacterial activity, expressed as MIC and MBC values, comparable or even superior to manuka honey for some tested samples. Although honey antibacterial activity is mainly attributed to hydrogen peroxide and proteins in some cases (demonstrated by elevated MICs after catalase and Proteinase K treatment, respectively), no strong correlation between the antibacterial activity and hydrogen peroxide concentration or total protein content was demonstrated in this study. However, there was a statistically significant correlation of moisture, antioxidant and antibacterial activity against Klebsiella pneuomoniae, as well as antioxidant and antibacterial activity against Salmonella ser. Typhimurium. Interestingly, a statistically significant negative correlation has been observed between diastase activity and Staphylococcus aureus antibacterial activity. Overall, our data indicate multiple mechanisms of antibacterial activity exerted by pine honey.

Antibacterial and antibiotic-potentiating activities of Desmodium uncinatum, Neoboutonia glabrescens, Ternstroemia cameroonensis and eight other Cameroonian medicinal plants against multi-drug resistant bacteria expressing active efflux pumps

Background: Infectious diseases remain a major public health problem in the world with a considerable impact in developing countries. Bacterial infections are of increasing concern due to the emergence and spread of bacteria resistant to antibiotics. Thus, it is necessary to develop methods and means to tackle drug resistance. The present study aimed at evaluating the antibacterial and antibiotic-potentiating activities of eleven Cameroonian medicinal plants: Sambucus nigra, Erigeron floribundus, Desmodium uncinatum, Neoboutonia glabrescens, Ficus exasperata, Sida rhombifolia, Echinaceae augustifolia, Centella asiatica, Tradescantia zebrina, Desmodium intortum and Ternstroemia cameroonensis against bacteria with multidrug-resistant (MDR) phenotypes. Methods: The microdilution method was used to assess the antibacterial activities of the extracts as well as the effect of their combination with antibiotics. The phytochemical screening of the extracts was carried out according to qualitative described methods. Results: The phytochemical screening revealed the presence of tannins, triterpenes, polyphenols, and flavonoids in almost all the extracts, with the other classes of secondary metabolites being selectively distributed. The tested extracts exhibited variable antibacterial activities, with minimum inhibitory concentrations (MICs) ranging between 512 and 1024 μg/mL. The Ficus exasperata leaves extract, Ternstroemia cameroonensis back extract, Erigeron floribundus whole plant extract, and Neoboutonia glabrescens leave extracts, presented the best spectra of inhibitions evaluated respectively at 60%, 60%, 70%, and 70% vis-à-vis all the bacterial strains tested. The whole plant extracts of Desmodium uncinatum and Centella asiatica, and of Ternstroemia cameroonensis have shown synergistic effects with more than 50% of the antibiotics (chloramphenicol, tetracycline, kanamycin, ciprofloxacin, ofloxacin, azithromycin and erythromycin) against more than 70% of the MDR bacteria tested. Conclusion: The present study demonstrated that extracts from the bark of Ternstroemia cameroonensis, Neoboutonia glabrescens and Ficus exasperata leaves, Desmodium uncinatum, and Erigeron floribundus whole plants can be used alone or in combination with antibiotics against bacterial infections involving MDR bacteria. Keywords: Antibacterial; antibiotics; medicinal plants; multidrug resistance.

Using least angular regression to model the antibacterial potential of metronidazole complexes

Imidazole has anti-inflammatory, antituberculotic, antimicrobial, antimycotic, antiviral, and antitumor properties in the human body, to name a few. Metronidazole [1-(2-Hydroxyethyl)-2-methyl-5-nitroimidazole] is a widely used antiprotozoan and antibacterial medication. Using fourier transform infrared spectroscopy, the current study models the antibacterial activity of already synthesised Metronidazole (MTZ) complexes (MTZ-Benz, MTZ-Benz-Cu, MTZ-Benz-Cu-Cl_2CHCOOH, MTZ, MTZ-Cu, MTZ-Cu-Cl_2CHCOOH, MTZ-Benz-Ag, MTZ-Benz-Ag-Cl_2CHCOOH, MTZ-Ag and MTZ-Ag-Cl_2CHCOOH) against E. coli, B. bronceptica, S. epidermidis, B. pumilus and S. aureus. To characterise the Metronidazole complexes for antibacterial activity against 05 microbes, the least angular regression and least absolute shrinkage selection operators were used. Asymmetric Least Squares was used to correct the spectrum baseline. Least angular regression outperforms cross-validated root mean square error in the fitted models. Using Least angular regression, influential wavelengths that explain the variation in antibacterial activity of Metronidazole complexes were identified and mapped against functional groups.

Variation in antibacterial properties of endophytic fungi isolated from Phaeophytes and Rhodophytes of Johor, Malaysia

Aim: To identify endophytic fungi of tropical macroalgae and analyse variation in antibacterial activity. Methodology: Endophytic fungi were aseptically isolated from macroalgae tissue, identified by macroscopic and microscopic observations, screened for the presence of antibacterial activity using cross streak and disc diffusion methods against six human pathogenic bacteria. Results: A total of 27 endophytic fungi were isolated and identified from 7 species of macroalgae collected from the Johor coast, Malaysia. Twenty-three fungal isolates belonged to Ascomycota, while two belonged to Zygomycota and Oomycota, respectively. Aspergillus niger was the most common and abundant endophyte found in macroalgal samples. Preliminary screening determined 13 species (48.15%) having positive antibacterial activity. Quantitative analysis of antibacterial activity showed significant differences (p< 0.01) against six human pathogenic bacteria. Two fungal isolates indicated strong and broad-spectrum antibacterial activity namely, Pythium sp. and Trichoderma viride. Interpretation: The findings demonstrate that certain macroalgae-derived endophytic fungi from Johor possess antibacterial properties and can be potentially new antibiotic sources, which are hitherto under-reported.

Antibacterial activity of Calotropis procera against some common human pathogens

Calotropis procera (Oshaar, family Asclepiadaceae) is a species of flowering plant used as a folk medicine for the treatment of various ailments. This study aimed to evaluate antibacterial and antioxidant activities of C. procera aerial parts collected from Eastern Desert of Egypt (Wadi Hagul). The different extracts of C. procera aerial parts showed a significant antimicrobial inhibitory effect (P < 0.05) on growth of nine pathogenic bacterial using filter paper disc assay. Qualitative and quantitative phytochemical screening was carried out on water and different extracts. The present study indicated that this plant has a good inhibitory activity against Klebsiella pneumonia (21.3 mm), Escherichia coli (22.5 mm), and Staphylococcus aureus (21.6 mm). Moreover, methanol extract of C. procera exhibited wide broad spectrum (100%) followed by petroleum ether and water extracts (60%, each). Activity index (AI) illustrated variable antibacterial activities, that support the folkloric usage of medicinal plants for treatment of infectious pathogenic microorganism. The crude extract of C. procera showed adequate antioxidant activity, wherein methanol, ethyl acetate and petroleum ether extracts have an IC50 value of 0.81, 0.88 and 1.09 mg mL-1, respectively. Therefore, phytochemicals from C. procera could be used as a raw material for producing cheaper pharmaceuticals, pesticides in addition to many more important commercialized products of public use.

Molecular Drug Design, Synthesis and Antibacterial study of Novel 4-Oxothiazolidin-3-yl Derivatives

New compounds containing 4-thiazolidinone pharmacophore 5(a) and (5b) have been synthesized. The chemical structures of the intermediate and final compounds were characterized and confirmed by using FT-IR and 1H-NMR spectroscopy. All final compounds were tested against gram-positive and gram-negative bacteria using a well-diffusion technique for their ability as antimicrobial agents. The tested compounds 5a and 5b showed variable and modest antibacterial activity against gram-negative bacteria and gram-positive bacteria. Molecular docking simulations were studied to understand the molecular core. The results were achieved by docking, the most active compounds into the active site of protein of the bacteria which completely accorded with in vitro results.

Molecular Drug Design, Synthesis and Antibacterial study of Novel 4-Oxothiazolidin-3-yl Derivatives

New compounds containing 4-thiazolidinone pharmacophore 5(a) and (5b) have been synthesized. The chemical structures of the intermediate and final compounds were characterized and confirmed by using FT-IR and 1H-NMR spectroscopy. All final compounds were tested against gram-positive and gram-negative bacteria using a well-diffusion technique for their ability as antimicrobial agents. The tested compounds 5a and 5b showed variable and modest antibacterial activity against gram-negative bacteria and gram-positive bacteria. Molecular docking simulations were studied to understand the molecular core. The results were achieved by docking, the most active compounds into the active site of protein of the bacteria which completely accorded with in vitro results.

Antimicrobial activity and Probiotic Properties of Lactic Acid Bacteria Isolated From Traditional Fermented Dairy Products

One of the biggest problems for humans and animals worldwide is the harmful effects of the antibiotics, due to excessive use as a treatment for animal diseases. An alternative to overcome this problem is the use of certain growth promoters such as probiotics that have a good effect on host health and performance. Eight isolates included the following probiotic strains: Lactobacillus plantarum, L. acidophilus, L.rhamnosus, L. salivarius, and L. paracasei, as well as Bifidobacterium longum, B. adolescentis, and B. breve were investigated for low pH and bile salt tolerance, anti-bacterial and yeast activity using supernatant cell-free culture were assessed using agar-well diffusion method against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, , Escherichia coli MC1400 Listeria ivanovii and Candida albicans. Co-culture has determined the antifungal activities with Aspergillus niger, As. flavous, As. fumigatus and Penicillium chrysogenum. The antibiotic sensitivity was tested using the agar disc diffusion method. Each of the strains examined had variable antibacterial activity. All the isolates showed a variable inhibition level, as well. All of the isolates were Ciprofloxacin resistant. Additionally, the lactobacilli strains were Vancomycin-resistant, and all of the strains show intermediate Clindamycin resistance. All isolates were Penicillin, Ampicillin, Tetracycline, Erythromycin, Gentamycin, Streptomycin, Florfenicol, Chloramphenicol, and Sulfamethoxazole & Trimethoprim susceptible. Collectively, the probiotic capacity of the strains tested and the antimicrobial activity without the transfer of antibiotic resistance suggested that these strains can be used as bio-preservatives in food products and medicinal preparations.

Quantitative Analysis of Polyphenols and Biological Activity of Sage Macerates

The total phenols concentration in two sage macerates has been estimated by Folin-Cioc�lteau method, identified and quantified using HPLC-DAD method in order to assess the biological activity. The results for total phenols values of Folin Ciocalteau method indicate that Salvia officinalis L macerate S2, presents a higher amount of phenolic compounds than macerate S1. By HPLC-DAD method, six individual phenolic compounds were identified in sage macerates among which where cinnamic acid was found in highest concentration (652.478 mg/100g d.w. in S2 and 473.381 mg/100g d.w. in S1). The antioxidant activity of sage macerates was evaluated using DPPH Radical Scavenging test. Sage macerates exhibited high antioxidant activity, between 439.5 mg GAE /mL and 400 mg GAE /mL. Antibacterial activity of sage macerates was evaluated against 20 Gram positive and Gram negative bacterial strains isolated from clinical specimens. Both macerates showed significant but variable antibacterial activity with inhibition zones ranging from 4.97 mm (S2) to 7.28.mm (S1). The effect was stronger on Gram positive (Enterococcus, Staphyococcus) than Gram negative bacteria (Escherichia sp, Proteus sp, Klebsiella sp). Eleven metals concentrations were determined by AAS method in sage leaves; it has been found that Cd, Ni and Pb concentrations are below the detection limits.

Quantitative Analysis of Polyphenols and Biological Activity of Sage Macerates

The total phenols concentration in two sage macerates has been estimated by Folin-Ciocâlteau method, identified and quantified using HPLC-DAD method in order to assess the biological activity. The results for total phenols values of Folin Ciocalteau method indicate that Salvia officinalis L macerate S2, presents a higher amount of phenolic compounds than macerate S1. By HPLC-DAD method, six individual phenolic compounds were identified in sage macerates among which where cinnamic acid was found in highest concentration (652.478 mg/100g d.w. in S2 and 473.381 mg/100g d.w. in S1). The antioxidant activity of sage macerates was evaluated using DPPH Radical Scavenging test. Sage macerates exhibited high antioxidant activity, between 439.5 mg GAE /mL and 400 mg GAE /mL. Antibacterial activity of sage macerates was evaluated against 20 Gram positive and Gram negative bacterial strains isolated from clinical specimens. Both macerates showed significant but variable antibacterial activity with inhibition zones ranging from 4.97 mm (S2) to 7.28.mm (S1). The effect was stronger on Gram positive (Enterococcus, Staphyococcus) than Gram negative bacteria (Escherichia sp, Proteus sp, Klebsiella sp). Eleven metals concentrations were determined by AAS method in sage leaves; it has been found that Cd, Ni and Pb concentrations are below the detection limits.

The Effects of Biostimulants, Biofertilizers and Water-Stress on Nutritional Value and Chemical Composition of Two Spinach Genotypes (Spinacia oleracea L.).

In the present study, the effect of biostimulants application on the nutritional quality and bioactive properties of spinach cultivated in protected environment under water stress conditions was evaluated. For this purpose, four commercially available biostimulant products (Megafol (MEG), Aminovert (AM), Veramin Ca (V), Twin Antistress (TA), and two spinach genotypes (Fuji F1 and Viroflay) were tested under two irrigation regimes (normal irrigation (W+), and water-holding (W–). Fat and carbohydrates content was favored by water stress when Megafol (MEGW+) and Veramin (VW+) were applied on Fuji plants, while calorific value was also increased by MEGW+ treatment. In contrast, protein and ash content increased when AMW– and TAW+ were applied on Viroflay plants. Raffinose and glucose were the most abundant sugars, followed by sucrose and fructose, with the highest contents recorded for Fuji plants when AMW+ (fructose, glucose and total carbohydrates), CW– (sucrose), and TAW– (raffinose) treatments were applied. Regarding organic acids, oxalic and malic acid which had the highest contents for the TAW– (Viroflay plants) and AMW– (Fuji plants) treatments, respectively. α- and γ-tocopherol were the only isoforms detected with MEGW– and VW– inducing the biosynthesis of α-tocopherol, while AMW+ increased γ-tocopherol content in Fuji plants. The main fatty acids were α-linolenic and linoleic acids which were detected in the highest amounts in AMW–, AMW+, and TAW+ the former and in AMW–, VW–, and CW+ the latter. Regarding phenolic compounds content, peak 12 (5,3′,4′-Trihydroxy-3-methoxy-6:7-methylenedioxyflavone-4′-glucuronide) was the most abundant compound, especially in Viroflay plants under normal irrigation and no biostimulants added (CW–). The antioxidant and cytotoxic activity of the tested samples did not show promising results when compared with the positive controls, while a variable antibacterial activity was recorded depending on the tested biostimulant, irrigation regime and genotype. In conclusion, a variable effect of the tested biostimulants and irrigation regimes was observed on bioactive properties and chemical composition of both spinach genotypes which highlights the need for further research in order to make profound conclusions regarding the positive effects of biostimulants under water stress conditions.

Antibacterial activity of lactobacilli strains isolated from Laban Rayeb “Egyptian traditional fermented milk” against Pseudomonas fluorescens and Escherichia coli in vitro

Lactobacilli are significant to dairy industry due to their involvement in the production of several fermented dairy products. The present study was conducted to assess the antibacterial activity of the of lactobacilli strains (Lactobacillus pentosus RMLB1, Lactobacillus acidophilus RMLB9, Lactobacillus plantarum RMLB20, Lactobacillus pentosus RMLB22 and Lactobacillus salivarius RMLB32) isolated from the Egyptian traditional fermented milk “Laban Rayeb”. The lactobacilli strains were evaluated using the agar-well diffusion assay against pathogenic strains of Pseudomonas fluorescens and Escherichia coli. Furthermore, the ability of these strains to adhere to human intestinal mucous was examined. The results indicated that all the LAB strains showed a variable antibacterial activity against P. fluorescens and E. coli. L. acidophilus RMLB9 and L. salivarius RMLB32 showed the highest inhibitory effect against both pathogens. Moreover, all strains adhered in vitro to intestinal mucous with variable extents. The highest adhesive level, compared to the reference strain of Bifidobacterium bifidum, was showed by L. plantarum RMLB20 followed by L. salivarius RMLB32 and L. acidophilus RMLB9. The obtained results highlight that the Egyptian traditional fermented milk “Laban Rayeb” could be a source for potential probiotic bacteria possessing good inhibitory activity against P. fluorescens and E. coli.

In vitro evaluation of methicillin-resistant and methicillin-sensitive Staphylococcus aureus susceptibility to Saudi honeys

BackgroundHoney has been increasingly recognized as a potential therapeutic agent for treatment of wound infections. There is an urgent need for assessment and evaluation of the antibacterial properties against wound pathogens of honeys that have not yet been tested.MethodsTen Saudi honeys collected from different geographical locations were screened initially for their antibacterial potential against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) by the agar well diffusion method. Manuka honey (UMF-12) was used for comparison. Of the tested honeys, the honey that exhibited the greatest antibacterial activity in the agar well diffusion assay was further evaluated for its minimum inhibitory concentration (MIC) against ten MRSA clinical isolates and three American Type Culture Collection (ATCC) reference strains by the microbroth dilution method.ResultsLocally produced honeys exhibited variable antibacterial activity against the tested isolates in the agar well diffusion assay. They were unable to exhibit antibacterial activity against MSSA and MRSA at 25% dilutions (w/v) in catalase solution. However, Sumra and Talha honeys showed a zone of inhibition at 50% dilutions (w/v) in catalase solution. This finding means that both honeys possess weak non-peroxide-based antibacterial activity. Moreover, Sumra honey showed a larger inhibition zone at 50 and 25% dilutions (w/v) in distilled water than Manuka honey against both MSSA and MRSA. This result demonstrates that Sumra honey has more hydrogen peroxide-related antibacterial activity or total antibacterial activity than Manuka honey. In addition, MIC results obtained through a microbroth dilution assay showed that Sumra honey inhibited the growth of all MRSA clinical isolates (n = 10) and reference strains [MRSA (ATCC 43300) and MSSA (ATCC 29213)] at lower concentrations (12.0% v/v) than those required for Manuka honey-mediated inhibition (14.0% v/v). This result means that Sumra honey has more peroxide or synergistic antibacterial activity than Manuka honey. An equivalent MIC (15.0% v/v) was observed for E. coli (ATCC 25922) between Manuka honey and Sumra honey.ConclusionsSumra honey may be used as an alternative therapeutic agent for infected wounds and burns, where additional hydrogen peroxide-related antibacterial activity is needed. In the future, the physiochemical characteristics of Sumra honey may be evaluated and standardized.

Evaluation and Comparison of Antibacterial Efficacy of Herbal Extracts in Combination with Antibiotics on Periodontal pathobionts: An in vitro Microbiological Study.

Background: In the past few decades focus of research has been toward herbal medicines because of growing bacterial resistance and side effects of antimicrobial agents. The extract derived from the plants may increase the efficacy of antibiotics when used in combination against pathogenic bacteria. In the current study, the synergistic antibacterial efficacy of plant extracts in combination with antibiotics has been assessed on selected periodontal pathogens. Methods: Ethanolic extracts were prepared from Salvadora persica (Miswak) and Cinnamomum zeylanicum (Ceylon cinnamon), by the soxhalate method. Plaque samples were collected from clinical periodontitis patients to isolate and grow the periodontal pathobionts under favorable conditions. Susceptibility of bacteria to the extracts was assessed by gauging the diameter of the inhibition zones. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of plant extracts were determined against each bacterium. Synergistic activity of plants extract in combination with antibiotics against the bacteria was also assessed by measuring the diameter of the inhibition zones. Results: Ethanolic extract of both the plants showed an inhibitory effect on the proliferation and growth of all four strains of periodontal pathobionts. Maximum antibacterial activity was exhibited by C. zeylanicum against Tannerella forsythia (MIC = 1.56 ± 0.24 mg/mL, MBC = 6.25 ± 0.68 mg/mL), whereas among all the studied groups the minimum activity was reported by C. zeylanicum against Aggregatibacter actinomycetemcomitans the (MIC = 12.5 ± 3.25 mg/mL, MBC = 75 ± 8.23 mg/mL). Combination of herbal extracts with different antibiotics revealed a synergistic antibacterial effect. The best synergism was exhibited by S. persica with metronidazole against A. actinomycetemcomitans (27 ± 1.78). Conclusions: Current in vitro study showed variable antibacterial activity by experimented herbal extracts against periodontal pathobionts. The synergistic test showed significant antibacterial activity when plant extracts were combined with antibiotics.

Evaluation of Bioactive Compounds on Different Extracts of Linum Usitatissimum and Its Antimicrobial Properties against Selected Oral Pathogens

Background: Antibacterial agents from natural sources have been suggested as alternatives for treating infectious diseases due to their low side effects. Flaxseed (Linum usitatissimum) exhibits some antibacterial properties, but its effects against oral pathogens are poorly understood. This study investigated flaxseed extracts' antibacterial effects against such pathogens. Methods: Non-polar and polar extracts of flaxseed, with n-hexane, dichloromethane (DCM) and methanol (MeOH), were prepared by sequential Soxhlet extraction. All extracts were qualitatively screened through gas chromatography-mass spectrometry to detect bioactive compounds. Antibacterial activities of flaxseed extracts with different volumes per disc (Oxoid, Badhoevedorp, Netherlands) (5, 7, 10, 12 and 15 µL/disc) were evaluated against four different oral pathogens: Streptococcus pyogenes, Streptococcus mutans, Lactobacillus casei and Enterococcus faecalis, using the disc diffusion method. Flaxseed extracts' inhibitory activities against the tested oral pathogens were examined by measuring the inhibition zone diameter. Results: Polar extract (methanolic extract) demonstrated significant antibacterial activity (p<0.01) against all tested oral pathogens, with inhibition zones comparable to those for penicillin. In contrast, n-hexane and DCM extracts demonstrated variable antibacterial activities. Conclusions: This study suggests that Linum usitatissimum methanolic extract exhibited the best inhibitory activity on all tested strains compared to the other extracts.