Antistaphylococcal effects of alcoholic extracts of Tetrapleura tetraptera (Schum and Thonn.) (Taub.) against multidrug methicillin resistant Staphylococcus aureus

Background: Staphylococcus aureus is a pathogen causing life-threatening hospital and community-acquired infections with high morbidity and mortality rates requiring constant vigilance.Aim: This study aimed at investigating the antistaphylococcal effects of Tetrapleura tetraptera against different strains of multidrug methicillin resistant S. aureus (MRSA) to indicate the need for its use in ethnomedicine in addition to its fruits being used in traditional medicine.Methods: In this study, the susceptibilities of S. aureus were investigated using multi-disc antibiotics and extracts of T. tetraptera by agar diffusion and macrobroth dilution methods.Settings: While attention has been focused on the fruits of this plant, it is necessary to investigate the pharmacological importance of its stem bark.Results: The antibiogram showed that 70% of the isolates were multidrug resistant. Nitrofurantoin and gentamicin antibiotics were the most effective whilst amoxicillin and augumentin were the least effective. The susceptibility of the isolates was concentration dependent as inhibition zones decreased with decrease in the concentrations of each of the extracts. The minimum inhibitory concentrations (MICs) of acetone extract ranged between 0.019 mg/mL and 20 mg/mL whilst the minimum bactericidal concentrations (MBCs) ranged between 0.3125 mg/mL and 20 mg/mL. The MICs of the methanol extract ranged between 0.039 mg/mL and 5.0 mg/mL whilst the MBCs ranged between 0.3125 mg/mL and 10 mg/mL. Both extracts were more bactericidal than being bacteriostatic against all the isolates. The methanol extract was more active than the acetone extract as indicated by the varied inhibition zones and MICs obtained from the different extracts.Conclusion: This study revealed the great therapeutic potentials of T. tetraptera and validated its use in ethnomedicine and would be effective in the treatment of multidrug and MRSA infections.

Preparation and Property of Antibacterial Nucleus with the Combination of Nano-Silver and Antibiotics

To improve the yield and quality of pearls in freshwater pearl culture and the survival rates after nucleus implanting surgery, pearl farmers used artificial pearl nuclear transplantation techniques to raise pearls. To address the common problem of Staphylococcus aureus and Escherichia coli infection in oyster farming, a new prophylactic method by using compound antibiotics to prepare the medicine coated pearl nucleus was put forward based on existing research results of the nanosilver antibacterial nucleus. Single-factor experiment, multi-factor experiment, orthogonal experiment, SPSS analysis of variance was used to optimize the antibacterial formulation on the assumption that the contaminated probability of these two pathogenic bacteria was the same. The result showed that the optimal ratio of compound antibiotics was 0.0075g/ml of the flavomycin solution and 0.01g/mL of the terramycin solution; the inhibition zones diameter of both pathogenic bacteria was more than 2.6cm in vitro, which was higher than the nanosilver antibacterial nucleus of 0.9cm in vitro. Indicating that the addition of this compound antibiotic formula for the nanosilver antibacterial nucleus could reduce the usage of antibiotics under the premise of maintaining antibacterial effectiveness, and could preferably inhibit the pathogenic microorganisms in the postoperative infection period. This also indicates that compound antibiotics coated antibacterial nanosilver nucleus would be applied more widely.

Non-Thermal Plasma Sources Based on Cometary and Point-to-Ring Discharges

A non-thermal plasma (NTP) is a promising tool against the development of bacterial, viral, and fungal diseases. The recently revealed development of microbial resistance to traditional drugs has increased interest in the use of NTPs. We have studied and compared the physical and microbicidal properties of two types of NTP sources based on a cometary discharge in the point-to-point electrode configuration and a corona discharge in the point-to-ring electrode configuration. The electrical and emission properties of both discharges are reported. The microbicidal effect of NTP sources was tested on three strains of the bacterium Staphylococcus aureus (including the methicillin-resistant strain), the bacterium Pseudomonas aeruginosa, the yeast Candida albicans, and the micromycete Trichophyton interdigitale. In general, the cometary discharge is a less stable source of NTP and mostly forms smaller but more rapidly emerging inhibition zones on agar plates. Due to the point-to-ring electrode configuration, the second type of discharge has higher stability and provides larger affected but often not completely inhibited zones. However, after 60 min of exposure, the NTP sources based on the cometary and point-to-ring discharges showed a similar microbicidal effect for bacteria and an individual effect for microscopic fungi.

ANTIFUNGAL ACTIVITY OF CHITOSAN AGAINST Rhizopus stolonifer

These days instead of chemical pesticides, various natural alternatives have been used for the management of post-harvest diseases. This research was carried out to evaluate the antifungal potential of different chitosan concentrations viz., 5, 10, and 15 mg/µl against Rhizopus stolonifer by the agar dilution and well diffusion methods. The evaluation was carried out after seven days of incubation by measuring the inhibition of R. stolonifer mycelial growth. Results of the study revealed that the chitosan had a significant inhibitory effect on mycelial growth and maximum mycelial growth inhibition was reported at the 10 and 15 mg/µl concentrations and these two treatments are not significantly different. Based on these results, the best concentration (15 mg/µl) was further evaluated by the well diffusion technique. The average inhibition zones formed by the higher concentration was 25mm. Results of the study suggested that chitosan can be used for the management of post-harvesting diseases of tomatoes.

Screening and Characterization of Soil Microbes Producing Antimicrobial Compounds in Makkah Province, Saudi Arabia

This study aimed to investigate a method to manage antimicrobial resistance (AMR) issues by exploring soil microorganisms that are capable of producing bioactive compounds. Eight different types of soil were selected from three locations to screen, isolate, and identify microorganisms that are capable of producing antimicrobial compounds. The multi-drug resistant strains are Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans were selected for primary and secondary screening using the crowded plate method and the agar well diffusion method. Inhibition zones were measured, and data were assessed using statistical tests to check for normality and differences between parametric variables and nonparametric data. This was followed by biochemical characterization, DNA isolation, and polymerase chain reaction (PCR). Molecular identification was performed using 16S rRNA amplification and sequencing. Here, 86 isolates containing bacteria and fungi were successfully extracted from soil samples. Further, 49 of 86 microbes showed possible antimicrobial activity, but only 12 isolates resulted in distinct inhibition zones with the selected multi-drug resistant strains. The following different taxa were identified: Firmicutes (nine strains), Proteobacteria (one strain), Actinobacteria (one strain), and Azotobacter (one strain). Species are represented in a phylogenetic tree, which was constructed using the unweighted pair-group method with arithmetic mean (UPGMA) method. The evolutionary distances were computed using the Maximum Composite Likelihood method. The identified microorganisms showed antimicrobial activity, confirming that soil microorganisms have great potential to address AMR issues.

Morphological, anatomical and antibacterial characteristics of Persicaria maculosa Gray plants growing in Lang Sen Wetland Reserve, Long An province, Vietnam

This study aimed to understand the adaptation characteristics of species Persicaria maculosa to living conditions and to add data on them as folk medicinal plants of Vietnam. Research methods included analysis of external morphological characteristics and microscopic structure of stems, leaves and roots. The antibacterial activities of ethanol plant extracts on four bacterial strains were also conducted through agar well diffusion method. The results showed that the plants had formed morphological and anatomical features to adapt to waterlogging and shade conditions. The leaf extracts from the concentrations of 600 to 1,000 mg/L had bacteriostatic activities against all four experimental strains with the bacterial inhibition zones from 2.39 to 10.91 mm, in which inhibition of Bacillus cereus was the best.

TLC-contact bioautography and disc diffusion method for investigation of the antibacterial activity of Melastoma malabathricum L. leaves

The emergence of multi-resistant strains of bacteria reinforces the need to discover new antibacterial agents that are able to combat resistant microorganisms. Medicinal plants are a valuable natural source of bioactive substances against various infectious diseases. Melastoma malabathricum L. is an important herb that is traditionally used to treat several ailments associated with microbial infection diseases such as wounds, diarrhea, dysentery, and toothache. This study investigated extracts of M. malabathricum L. for antibacterial properties against Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus (MRSA). Disc diffusion and TLC-contact bioautography techniques were employed to examine antibacterial properties of n-hexane, ethyl acetate, and ethanol extracts with observations of diameter inhibition zones and Rf values. Investigation of active compounds in TLC-bioautography used several reagents including citroboric, cerium (IV) sulfate and 2,2-diphenyl-1-picrylhydrazyl (DPPH), continued by identification of chromatogram profiles through densitometry analysis. The three extracts showed good inhibition against bacterial strains with diameter inhibition zones in the range of 8.0 – 14.0 mm with a number of active spots on TLC-contact bioautography for each extract. This plant may serve as useful source of antibacterial agents for resistant microorganisms and further investigation is needed of its bioactive pure compounds as well as their particular therapeutic potentials and applications.

Effects of Natural Antimicrobials on Xanthomonas Strains Growth

The aim of this work was to investigate the most promising natural antimicrobials effective for the growth suppression of Xanthomonas spp. bacteria. The research objects were Xanthomonas spp. strains isolated from tubers and stem of plants growing in Lithuania: Xanthomonas translucens NRCIB X6, X. arboricola NRCIB X7, NRCIB X8, NRCIB X9, and NRCIB X10; the supernatants of lactic acid bacteria Lactococcus lactis strains 140/2, 57, and 768/5, Lactobacillus helveticus strains 14, 148/3, R, and 3, Lb. reuteri 3 and 7, Streptococcus thermophilus 43, Enterococcus faecium 59-30 and 41-2; endophytic bacterial strains Bacillus, Pseudomonas, and Paenibacillus spp.; and essential oils of lavender (Lavandula angustifolia), grapefruit (Citrus paradisi), pine (Pinus sylvestris), thyme (Thymus vulgaris), rosemary (Rosmarinus officinalis), peppermint (Mentha piperita), lemon (Citrus limetta), aqueous extracts of blueberries (Vaccinium myrtillus), and cranberries (Vaccinium vitis-idaea). The antimicrobial activity of tested substances was determined by agar diffusion method. Supernatants of Lb. reuteri strain 7 and Lb. helveticus strains 14, R, 3, and 148/3 were found to have a high antimicrobial activity against Xanthomonas spp. bacteria strains when compared to the positive control—1.0% copper sulfate (diameter of inhibition zones was 28.8 ± 0.7 mm). The diameter of inhibition zones of supernatants ranged from 23.3 ± 0.6 mm to 32.0 ± 0.1 mm. Thyme (2.0%) and lavender (2.0%) essential oils inhibited the growth of Xanthomonas spp. strains. The diameter of the inhibition zones was from 14.7 ± 0.8 mm to 22.8 ± 0.9 mm. The aqueous extracts of blueberries had a weak antimicrobial activity. The diameter of inhibition zones ranged from 11.0 ± 0.2 mm to 13.0 ± 0.2 mm.

Preparation and Assessment of Antimicrobial Property of Resin Based Composites Impregnated with Proanthocyanidin and Titanium Dioxide

OBJECTIVE: To synthesize three experimental resin based composites (RBCs) out of a commercial preperation (Control) by impregnating into each a fixed weight (0.01%) of titanium dioxide (TiO2) and three different weight % (0.01, 0.02 and 0.03) of proanthocyanidin (PA) and to compare antibacterial property, from the zones of inhibition of streptococcus mutans (S. mutans), of the specimen restorations made in the experimental and control RBCs. METHODOLOGY: In the first phase, Streptococcus mutans were isolated and identified from the oral cavity of patients and identified on the basis of morphogenic appearance of colonies and confirmed through catalase test and microscopic examination. Isolates were then incubated and cultured for sensitivity. Specimens for control and experimental RBCs were made through a metallic mold having 2mm thickness and 5mm diameter for all the 4 groups. Specimen restorations made in the commercial as supplied RBC acted as the control (Group A). Specimen restorations in the Group B, C, and D were made in each of the experimental RBCs modified with 0.01% proanthocyanidin (PA) and 0.01% titanium dioxide (TiO2), 0.02% PA and 0.01% TiO2 and 0.03% PA and 0.01% TiO2. The antimicrobial property of all the specimen restorations in all the groups was evaluated by Bauer-Kirby (Disc Diffusion) method through the formation of zones of inhibition of S. mutans colonies on blood agar plates. Data were computed using SPSS version 21 for descriptive statistics and analyzed using one-way ANOVA with p value 0.05 taken as significant. RESULTS: The range of the zone of inhibition for specimen RBC restorations (N= 12) containing PA and TiO2 was 0.00 for Group A, 10-12mm for Group B, 12-14mm for Group C and 9-10mm for Group D. The mean inhibition zone for the experimental restoration specimens was 11±2mm for Group B, 12.7±1mm for Group C and 9.7±1mm for Group D compared to no inhibition zones (0.00 mm) with the control RBC Group A. The order of the inhibition zones from maximum to minimum was Group C > Group B > Group D > Group A. The differences between the mean values for the control and the experimental RBC restoration specimens were significant (p < 0.000). The specimen restorations in the Group D appeared under cured and could impact on their mechanical properties. CONCLUSION: Irrespective of the mentioned concentrations, impregnating PA and TiO2 rendered the RBC antimicrobial. RBC restorations made with the experimental RBC with 0.02% PA and 0.01% TiO2 proved relatively more effective in terms of antimicrobial effect. KEY WORDS: dental materials, resin based dental restorations, antibacterial resin based composite, proanthocyanidin, titanium dioxide.

Synthesis, characterization and evaluation of antibacterial activity of copper(II)-curcumin complex against staphylococcus aureus

Curcumin, a phytochemical from turmeric, and its derivatives have been extensively investigated from both chemical and biological strategies. However, the main problem encountered while using curcumin in clinical trials is its poor solubility and rapid degradation, resulting in its low levels in tissues, thus decreasing the medicinal effect of curcumin. To overcome these problems several synthetic approaches have been carried out to prepare new derivatives possessing better properties. Curcumin as a β-diketone ligand can act as chelating ligands toward a variety of metals to form stable complexes. Some studies showed that a metal-curcumin complex displayed potential medicinal activities. In this work, a copper(II)-curcumin complex was synthesized in a two-step procedure: (i) curcumin was separated from commercial turmeric powder using chromatography techniques and (ii) the copper(II) chloride (1 eq.) and pure curcumin (2 eq.) were mixed together in ethanol. The mixture was stirred at 60 oC for 3 hours to afford a stoichiometric copper(II)-curcumin complex. The curcumin ligand and its copper(II) complex were characterized by UV-Vis, IR, NMR spectroscopic methods, from which it was found that copper atoms are coordinated through keto-enol groups of two curcumin molecules. The ground state spectral features of the copper(II)-curcumin complex were consistent with that of the 1:2 copper(II)-curcumin complex. The antibacterial activities of curcumin ligand and its complex were evaluated against Staphylococcus aureus (ATCC 6538) using a well diffusion method on nutrient agar. The results showed that the inhibitory activity was not observed for free curcumin at any concentrations while the copper(II)-curcumin complex exhibited the inhibition zones (mm) of 7.8, 11.6 and 14.9 at various concentrations (mg/mL) of 1.0, 5.0 and 15.0, respectively.