Lowest Minimum Bactericidal Concentration Research Articles

Preparation and in vitro/in vivo evaluations of novel ocular micelle formulations of hesperetin with glycyrrhizin as a nanocarrier

The purpose of this study was to explore the potential of formulating hesperetin into an ophthalmic solution with dipotassium glycyrrhizinate (DG) as a micelle nanocarrier. A DG-based micelle ophthalmic solution encapsulating hesperetin (DG-Hes) was developed and its in vitro/in vivo characterizations were evaluated. The optimal formulation featured a DG/hesperetin (Hes) weight ratio of 12:1 and an encapsulation efficiency of 90.4 ± 1.7%; The optimized DG-Hes was characterized as small uniform spheres with an average micelle size of 70.93 ± 3.41 nm, a polydispersity index of 0.11 ± 0.02, and an electrically negative surface (−36.12 ± 2.79 mV). The DG-Hes ophthalmic solution had good tolerance in rabbit eyes. DG-Hes significantly improved the in vitro passive permeation, ex vivo corneal permeation, and in vivo ocular bioavailability of Hes. DG-Hes showed markedly increases in in vitro antioxidant activity. In vitro antibacterial activity tests revealed a lower minimum inhibitory concentration and lower minimum bactericidal concentration for DG-Hes ophthalmic solution were lower than for free Hes. DG-Hes ophthalmic solution also significantly reduced symptoms of eye infection in the rabbit bacterial keratitis model when compared to a Hes suspension. These results suggest that DG-Hes eye drops may be useful as a new ophthalmic preparation for the treatment of ocular diseases, especially bacterial ophthalmopathy.

Preliminary Evaluation of In Vitro Bacteriostatic and Bactericidal Effect of Salt on Leptospira spp.

Environmental resistance is an important factor for understanding the epidemiology of leptospirosis. Recently, new Leptospira hosts were identified, including also marine mammals. Moreover, halotolerant Leptospira strain, isolated from the environment and animals, highlighted the capability of this microorganism to persist in the seawater. The aim of this research was to investigate the bacteriostatic and bactericidal effect of salt on Leptospira strains belonging to 16 different serovars. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were verified through the microdilutions method starting from a 20% sodium chloride concentration. MIC values obtained were between 0.3125% and 10% of salt, while MBC values between 0.625% and >20%. Icterohaemorrhagiae (MIC: 0.3125%; MBC: 0.625%) resulted the most inhibited serovar, while the most resistant was Tarassovi (MIC: 10%; MBC: >20%). Interestingly, trends were reported for Pomona (MIC: 1.25%; MBC: >20%) and Bratislava (MIC: 0.625%; MBC: 20%), highlighting low MIC values but high MBC values. This is the first investigation aimed at the in vitro effect of salt on the growth of Leptospira spp. reference strains.

Antibacterial properties of lauric acid in combination with organic acids against major pathogens causing dairy mastitis

The objective of this study was to determine the antibacterial properties of lauric acid in combination with acetic acid and lactic acid against major dairy mastitis pathogens including Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, Escherichia coli and Klebsiella spp. The antibacterial effect of each acid and the acid mixtures was evaluated by their minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC) using broth microdilution method. The differences in, MIC and MBC values of lauric acid and acid mixtures for each pathogen were calculated by applying the one-way analysis of variance (ANOVA) and Turkey’s multiple-range tests were used for pairwise comparison. Results demonstrated that acetic acid had the highest inhibitory and bactericidal effect against all tested pathogens with the lowest MIC and MBC values of 0.125% and 0.25-1 %w/v, respectively. The mixture of lauric acid with acetic and lactic acid exhibited significant higher inhibitory and bactericidal effects by having the lower MIC and MBC values against all tested pathogens when compared with lauric acid alone (P < 0.05). In conclusion, acetic and lactic acid can enhance antibacterial properties of lauric acid against major mastitis pathogens.

Green and efficient biosynthesis of pectin-based copper nanoparticles and their antimicrobial activities.

Herein, we reported a green biosynthesis method of copper nanoparticles (CuNPs) at microwave irradiation condition by using pectin as a stabilizer and ascorbic acid as a reducing agent. Under the optimum conditions, CuNPs1 and 2 were synthesized under microwave times 0 and 3min, respectively. Transmission electron microscope and scanning electron microscope(SEM) tests showed that CuNPs1 and 2 had irregular polygon particles with average diameters of 61.9 ± 19.4 and 40.9 ± 13.6nm, respectively. Zeta potentials of CuNPs1 and 2 were -45.2 and -48.7mV, respectively. X-ray diffraction, Fourier transform infraredspectroscopy (FTIR), thermogravimetric analysis(TGA), and X-ray photoelectron spectroscopy techniques were used to characterize the properties of CuNPs. Furthermore, inhibition zone tests showed that CuNPs2 exhibited higher antimicrobial activities against Escherichia coli, Staphylococcus aureus, and Aspergillus japonicus than CuNPs1. The antibacterial activities were also studied by the bacterial growth kinetics in broth media, and CuNPs2 exhibited lower minimum bactericidal concentrations than CuNPs1.

Relief of Biofilm Hypoxia Using an Oxygen Nanocarrier: A New Paradigm for Enhanced Antibiotic Therapy.

Biofilms are chief culprits of most intractable infections and pose great threats to human health. Conventional antibiotic therapies are hypodynamic to biofilms due to their strong drug resistance, closely related with biofilm hypoxia. A new strategy for enhanced antibiotic therapy by relieving biofilm hypoxia is reported here. A two‐step sequential delivery strategy is fabricated using perfluorohexane (PFH)‐loaded liposomes (lip) as oxygen (O2) carriers (denoted as lip@PFH@O2) and commercial antibiotics. The results indicate that the two‐step sequential treatment exhibits much lower minimum bactericidal concentrations than the antibiotic treatment alone. In this design, the lip@PFH@O2 holds positively charged surface for better biofilm penetration. After penetrating into biofilm, oxygen can be released from lip@PFH@O2 by inches, which greatly relieves biofilm hypoxia. With the relief of hypoxia, the quorum sensing and the drug efflux pumps of bacteria are suppressed by restraining related gene expression, leading to the reduced antibiotic resistance. Furthermore, the in vivo experimental results also demonstrate that lip@PFH@O2 can effectively relieve biofilm hypoxia and enhance therapeutic efficacy of antibiotics. As a proof‐of‐concept, this research provides an innovative strategy for enhanced antibiotic therapy by relieving hypoxia, which may hold a bright future in combating biofilm‐associated infections.

Green synthesis of zinc oxide nanoparticles using Citrus sinensis peel extract and application to strawberry preservation: A comparison study

ZnO nanoparticles synthesized by Citrus sinensis peel extract (SNP) were characterized and compared with commercial ZnO nanoparticles (CNP), and were then applied as nanocoatings on fresh strawberries to evaluate the preservation effect. The results revealed that SNP had a similar crystal structure to CNP, but a higher crystallinity and a larger particle size. The cytotoxicity of SNP towards human umbilical vein endothelial cells (HUVECs) was close to CNP when the concentration was below 25 mg/L. Furthermore, SNP and CNP had a similar minimum inhibitory concentration (MIC) against E. coli and S. aureus, but SNP showed a significantly lower minimum bactericidal concentration (MBC) against E. coli compared with CNP. Higher antifungal activities of CNP against Botrytis cinereal purified from mildewed strawberries compared with SNP were found when the concentration was lower than 400 mg/L. When SNP and CNP were incorporated into carboxymethylcellulose sodium (CMC) and coated on fresh strawberries, both coatings significantly decreased the weight loss and the rate of rotting, and also improved the storage quality. Therefore, SNP prepared by the green method has great potential in food packaging application.

Physical characteristics and antimicrobial properties of Apis mellifera, Frieseomelitta nigra and Melipona favosa bee honeys from apiaries in Trinidad and Tobago

BackgroundHoney is a versatile and complex substance consisting of bioactive chemicals which vary according to many bee and environmental factors. The aim of this study was to assess the physical and antimicrobial properties of five honey samples obtained from three species of bees; two stingless bees, Frieseomelitta nigra and Melipona favosa and one stinging bee, Apis mellifera (fresh and aged honey). Samples were acquired from apiaries across Trinidad and Tobago. An artificial honey, made from sugar, was also used for comparison.MethodsPhysical properties such as appearance, pH, moisture content, sugar content and specific gravity were determined. Antimicrobial activity was assessed utilizing the agar diffusion assay and comparison to a phenol equivalence. The broth microdilution test was performed to determine the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of the five honey samples against four common pathogens, including Staphylococcus aureus, Escherichia coli, Streptococcus pyogenes and Haemophilus influenzae.ResultsAll honey samples were acidic, with pH values ranging from 2.88 (M. favosa of Tobago) to 3.91 (fresh A. mellifera). Sugar content ranged from 66.0 to 81.6% with the highest values detected in stinging bee honeys of the A. mellifera (81.6 and 80.5°Bx). Moisture content ranged from 16.9% for aged A. mellifera honey (from Trinidad) to 32.4% for F. nigra honey (from Tobago). The MICs (2 to 16%) and MBCs (2 to 32%) of stingless bee honeys were lower than that of stinging bee and artificial honeys (16 to > 32%). Stingless bee honeys also exhibited a broad spectrum of antimicrobial activity against both Gram-positive and Gram-negative organisms with higher phenol equivalence values (4.5 to 28.6%) than the A. mellifera honeys (0 to 3.4%) against the isolates tested. M. favosa honey of Tobago displayed the greatest antimicrobial activity as indicated by the high phenol equivalence and low MIC and MBC values.ConclusionsStingless bee honeys from Tobago showed the greatest antimicrobial activity when compared to the other honeys used in this study. M. favosa honey of Tobago showed the most potential for use as medicinal honey.

Screening of Potential Bioactive Peptides from Bivalves of Donax cuneatus and Pitar erycina: A Peptide MALDI-ToF-Mass Fingerprinting Approach

The unexplored marine bivalves: Donax cuneatus and Pitar erycina are collected and the crude tissue proteins are extracted from them by diverse extraction methods. The crude protein fraction obtained from the acidic extraction method showed the highest yield and have further considered in our study. Various process parameters for the crude peptide extraction was statistically optimized based on response surface methodology revealed that the predicted peptide concentration from the polynomial model was 17.32 mg/mL, based on of the predicted process variables, i.e., 13.36 g/mL solid/liquid ratio, 26.63 °C temperature and 18.36 min of homogenization time. Subsequently, the crude peptide fraction isolated was subjected to purification by column chromatography followed by RP-HPLC. The fraction 3a from Donax cuneatus and 5b from Pitar erycina showed the highest antibacterial activity against Proteus vulgaris (20 µg/mL), Klebsiella pneumonia (10 µg/mL) and Streptococcus pyogenes (10 µg/mL) when compared to that of standard drug chloramphenicol at 40, 20 and 10 μg/mL respectively. Besides, the lowest minimum bactericidal concentration observed against Klebsiella pneumonia and Salmonella typhi for both the purified peptides was10 µg/mL. These antimicrobial peptides 3a and 5b exhibited significantly high antibacterial activity at 2× concentration of minimum inhibitory concentration, as evidenced through the in-vitro time-kill kinetic assay. They found to suppress the growth of all pathogenic bacteria under evaluation after 4 h. In addition to the above results, MALDI ToF-MS revealed the molecular mass of the peptide fractions 3a and 5b was 10.5 kDa and 10.0 kDa, respectively. Thus, the purified antimicrobial peptides isolated from the crude protein extracts from Donax cuneatus and Pitar erycina are found to be potential against the tested dreadful pathogens and could be translated for preclinical research in the future.

Antibacterial activity of compounds isolated from Caesalpinia coriaria (Jacq) Willd against important bacteria in public health

Antimicrobial resistance has been increasing in recent years and is most frequently found in pathogenic microorganisms resistant or multiresistant to drugs. The secondary metabolites of plants have been evaluated as alternatives for control and treatment of these microorganisms. The aim of this study was to isolate and identify the secondary metabolites with antibacterial activity from Caesalpinia coriaria (Jacq) Willd fruit. Hydroalcoholic extract (CCHA), was subjected to a bipartition with ethyl acetate giving two fractions an aqueous (Aq-F) and an organic (EtOAc-F). The isolation of bioactive fraction (EtOAc-F) allowed obtain two important compounds, methyl gallate (1) and gallic acid (2). These compounds were identified by high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR). The CCHA, both fractions and the isolated compounds were evaluated in vitro to determine their Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) against Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Listeria monocytogenes and Staphylococcus aureus. Gallic acid (2) showed the lowest MIC on S. typhi, (0.156 mg/mL), L. monocytogenes and S. aureus (1.25 mg/mL), while methyl gallate (1) had the best inhibitory effect against E. coli and P. aeruginosa (1.25 mg/mL). On the other hand, methyl gallate (1) showed the best MBC on P. aeruginosa (2.50 mg/mL), and gallic acid (2) had the lowest MBC on P. aeruginosa and L. monocytogenes. In conclusion, methyl gallate (1) and gallic acid (2) are the compounds responsible for the antibacterial activity of Caesalpinia coriaria fruit.

The Salmonella Specific, σE-Regulated, STM1250 and AgsA, Function With the sHsps IbpA and IbpB, to Counter Oxidative Stress and Survive Macrophage Killing.

The host presents an array of environments which induce bacterial stress including changes in pH, antimicrobial compounds and reactive oxygen species. The bacterial envelope sits at the interface between the intracellular and extracellular environment and its maintenance is essential for Salmonella cell viability under a range of conditions, including during infection. In this study, we aimed to understand the contribution of the σH- and σE-regulated small heat shock proteins IbpA, IbpB, and AgsA and the putative σE-regulated stress response protein STM1250 to the Salmonella envelope stress response. Due to shared sequence identity, regulatory overlap, and the specificity of STM1250 and AgsA to Salmonella sp., we hypothesized that functional overlap exists between these four stress response proteins, which might afford a selective advantage during Salmonella exposure to stress. We present here new roles for three small heat shock proteins and a putative stress response protein in Salmonella that are not limited to heat shock. We have shown that, compared to WT, a quadruple mutant is significantly more sensitive to hydrogen peroxide, has a lower minimum bactericidal concentration to the cationic antimicrobial peptide polymyxin B, and is attenuated in macrophages.

In Vitro Antioxidant and Bactericidal Efficacy of 15 Common Spices: Novel Therapeutics for Urinary Tract Infections?

Background and Objectives: Bacterial urinary tract infection (UTI) is the most common ailment affecting all age groups in males and females. The commercial antibiotics usage augments antibiotics resistance and creates higher recurrence rates of such communal infections. Hence, this study is aimed at investigating the antibacterial and antioxidant potentials of 15 common spices against 11 UTI-causing bacterial pathogens. Materials and Methods: The antioxidant potential of the methanolic extracts was analyzed as contents of total phenols and flavonoids; radical scavenging, total reducing power, the ferric reducing power assay. Urinary pathogens were subjected to spice extracts to investigate antibacterial assays. Results: Preliminary phytochemical study of spices was performed to find those containing alkaloids, flavonoids, phenolic compounds, and steroids that can be recognized for their noteworthy bactericidal effects. The outcome of the antioxidative potential from the four methods demonstrated the sequence of potent antioxidant activity: Acorus calamus >Alpinia galanga > Armoracia rusticana > Capparis spinosa > Aframomum melegueta. The total polyphenols and flavonoids in the studied species positively correlated with their antioxidant properties. The four most effective spices (A. calamus, A. galanga, A. rusticana, and C. spinosa) had a zone of inhibition of at least 22 mm. A. calamus, A. melegueta, and C. spinosa had the lowest minimum inhibitory concentration (MIC) value against Enterobacter aerogenes, Staphylococcus aureus and Proteus mirabilis. All 15 spices had the lowest minimum bactericidal concentration (MBC) value against most of the pathogenic bacteria. Conclusion: The four highly potent and unique spices noted for the in vitro control of UTI-causing pathogens could be pursued further in the development of complementary and alternative medicine against UTI-causing pathogens.

In vitro antibacterial activity of Bunium persicum and Rheum ribes on Acinetobacter baumanii

Introduction: Using antibiotics to control pathogenic bacteria is associated with certain side effects in addition to emergence of drug resistance. Nowadays, researchers are considering using plants as suitable alternatives to antibiotics. The aim of study was to compare in vitro antimicrobial activities of aqueous and hydroalcoholic Bunium persicum and Rheum ribes L. extracts on Acinetobacter baumanii. Materials and methods: Different concentrations of R. ribes and B. persicum were prepared to determine microbial sensitivity of A. baumanii using disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). Results: The highest MIC (256 µg/ml) against A. baumanii was derived for aqueous R. ribes and B. persicum extracts and the lowest MIC (128 µg/ml) for their hydroalcoholic extracts. The highest MBC (512 µg/ml) was derived for aqueous R. ribes extract and the lowest MBC (256 µg/ml) for aqueous and hydroalcoholic R. ribes and B. persicum and hydroalcoholic R. ribes extracts. The extracts exhibited great inhibitory effects against the studied bacteria in disk diffusion; and with increasing the extracts’ concentrations, the inhibitory effect was exhibited more markedly as increased diameter of inhibition zone. Conclusion: Hydroalcoholic R. ribes and B. persicum extracts can be used as nature-based compounds to control A. baumanii.

Improved antibacterial effects of alkali-transformed saponin from quinoa husks against halitosis-related bacteria

BackgroundQuinoa is a food crop native to the Andes. The process of dehulling quinoa can produce approximately 8–12% husk, which is often discarded because it contains bitter saponin. Saponin derived from quinoa has been reported to exhibit anti-inflammatory and antifungal activity. However, the antibacterial effects of quinoa saponin against halitosis-related bacteria are still unclear.MethodsIn this study, quinoa saponin (QS) and alkali-transformed saponin (ATS) were separated by AB-2 resin to obtain QS-30, QS-80, ATS-30 and ATS-80. Halitosis-related bacteria included Porphyromonas gingivalis (P. gingivalis), Clostridium perfringens (C. perfringens) and Fusobacterium nucleatum (F. nucleatum). The MIC and MBC were determined using gradient dilutions in 96-well plates, and the saponins were identified by HPLC and mass spectrometry. The changes in membrane integrity were tested using a microplate reader, the membrane potential was tested by spectrofluorometry, and the morphological characteristics were examined using a transmission electron microscope to explore the antibacterial mechanisms.ResultsAntibacterial assays indicated that QS-80 and ATS-80 showed inhibitory activity. In addition, ATS-80 exerted a stronger inhibitory effect than QS-80, especially against Fusobacterium nucleatum, with a lower minimum inhibitory concentration (31.3 μg/mL) and a lower minimum bactericidal concentration (125 μg/mL). ATS-80 destroyed the bacterial membrane structure, leading to bacterial death.ConclusionsBased on the excellent antibacterial activity and economic prospects of quinoa husk, ATS-80 could be used as an antibacterial agent to treat halitosis.

A new approach to determination of bactericidal activity of benzylpenycylin on Corynebacterium diphtheriae

Information on the bactericidal activity of benzylpenycylin is important when planning antibiotic therapy for a number of diseases caused by Corynebacterium diphtheriae (endocarditis, bacteremia, septicemia, etc.). However, methods for determining the minimum bactericidal concentration (MBC) of antibiotics are complicated. The aim of the study was to develop a method for testing of diphtheria causative agent susceptibility to the bactericidal action of penicillin without MBC determination. The minimum inhibitory concentrations (MICs) and MBCs in 80 strains of C. diphtheriae were determined using the standard broth dilution method (macromethod). The MICs were registered after 24 and 48 years of growth. After the first day of growth the MIC of penicillin was in the range of 0.017 to 0.5 mg / L, after second day — in the range of 0.035 to 0.5 mg / liter. The increase of the MICs for the second day of growth was observed in 47.5±5.6% of strains. MIC50 and MIC90 both after 24 hours and after 48 hours of growth were 0.13 and 0.25 mg/L, respectively. MBCs of penicillin was in the range of 0.5 to 32.0 mg/L, MBC50 was 4.0 mg/l, MBC90 – 8.0 mg/l. In 35,0±5,3% of the studied strains, high MBCs (8.0 mg / l or higher) was detected. It has been established that in C.diphtheriae the relationship between the MIC and the MBC of penicillin is clearly expressed, taking into account the two values of the MIC – for the first and second day of growth. Investigated strains are divided into three conditional groups: 1) with MIC 0.13 mg/L and basically with low MBCs; 2) with MIC 0.25 mg/L, in most cases are not susceptible to bactericidal action, and 3) strains with MIC 0.5 mg/L and high MBCs. The most pronounced were differences in the prevalence of corynebacteria with high MBCs in two groups of strains: MICs which did not exceed 0.13 mg/L after 24 and 48 hours, and those in whom the MIC was 0.25 mg/L or higher already on the first day of incubation (Student's coefficient t=4.13, p<0.001). The obtained results can be used to improve the methods for determining of corynebacteria susceptibility to antimicrobials.

Antimicrobial activity of pomegranate peel extracts performed by high pressure and enzymatic assisted extraction

This study aimed to assess the effect of high pressure (300 and 600 MPa) and enzymatic extraction (pectinase and cellulase) on the phenolic compounds profile, antioxidant capacity and antimicrobial activity of extracts from pomegranate by-products. Antimicrobial activity against eight different strains of pathogenic and contaminant bacteria and against five beneficial bacteria including Lactobacillus and Bifidobacterium strains were determined.The maximum level of total phenolic content, as well as antioxidant capacity were observed at 300 MPa, however enzymatic extraction did not improve the extraction yields. Punicalagin isomers and bis-hexahydroxydiphenoyl-glucoside isomer were the most abundant phenolic compounds found in the extracts. All pomegranate peel extracts demonstrated selective antimicrobial activity against all pathogenic bacteria without affecting beneficial ones. Pressurized extracts presented lower minimum inhibitory concentration against Bacillus cereus and Pseudomonas aeruginosa and lower minimum bactericidal concentration against B. cereus, while, enzymatic extracts presented lower minimum bactericidal concentration for Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus and Listeria monocytogenes. Principal component analyses reveled that antioxidant activity and phenolic compounds content were strongly related with antimicrobial activity. Pomegranate peels extracts obtained by high pressure extraction could so be used as a source of high added-value bioactive compounds for antioxidant and antimicrobial applications.

Phytochemical profile and antimicrobial properties of volatile compounds of <i>Satureja calamintha</i> (L) Scheel from northern Algeria

Purpose: To undertake the phytochemical screening of Satureja calamintha (L.) Scheel., and evaluate the antimicrobial activities of its volatile compounds.Methods: Qualitative phytochemical analysis of the plant was performed using standard methods. The extraction of essential oils (EOs) was conducted using steam distillation, while the chemical composition was determined using gas chromatography-mass spectrometry (GC-MS). The antimicrobial activities of the oils were evaluated against ten bacterial and six fungal strains using disc-diffusion assay and poisoned food technique, respectively.Results: After steam distillation, the extraction yield was 0.54 ± 0.11 %. GC-MS analysis identified approximately 99.99 % of the EOs. The three most abundant compounds identified were l-menthone (32.10 %), neo-menthol (32.07 %) and pulegone (22.35 %). The oils had significant (p < 0.05) antimicrobial activities against the tested bacterial and fungal strains, except Bacillus cereus and Candida albicans. The lowest minimum inhibitory concentration (MIC) for bacteria was 0.007 % (v/v) against Enterococcus faecalis and Klebsiella pneumoniae, whereas for fungi, it was 0.500 % (v/v) against Candida albicans. Moreover, Enterococcus faecalis and Listeria innocua had the lowest minimum bactericidal concentration (MBC) at 0.125 % (v/v), in contrast to the lowest fungicidal concentration (MFC) for Candida albicans at 0.500 % (v/v).Conclusion: These results demonstrate that EOs from Satureja calamintha (L.) Scheel. possess significant antimicrobial activities which might be useful for therapeutic and pharmaceutical applications.Keywords: Satureja calamintha, Phytochemicals, Essential oils, Antimicrobial activity, Steam distillation

In vitroefficacy of a honey‐based gel against canine clinical isolates ofStaphylococcus pseudintermediusandMalassezia pachydermatis

Staphylococcus pseudintermedius and Malassezia pachydermatis are important agents in canine pyoderma and otitis. Determine the invitro efficacy of a honey-based gel (HBO) against meticillin-susceptible S.pseudintermedius (MSSP), meticillin-resistant S.pseudintermedius (MRSP) and M.pachydermatis, by minimum bactericidal concentration (MBC), minimum fungicidal concentration (MFC) and time-kill assay (TKA). Efficacy of the product's honey component (HO) also was evaluated. Sixty S.pseudintermedius and 10M.pachydermatis canine isolates were selected. All isolates were tested against serial dilutions of an HBO containing 40% HO (40%, 20%, 10%, 5% and 2.5% w/v) and HO alone (undiluted, 40%, 20%, 10%, 5% and 2.5% w/v). Microbroth assay followed by subculture was used to determine MBC and MFC. The same protocol was applied after product exposure to catalase. A well-diffusion assay for S.pseudintermedius was used to generate inhibition zones. A TKA for 10 isolates of S.pseudintermedius and 10 isolates of M.pachydermatis was performed. MBC was 20% w/v (5-20% w/v) for HBO and HO. HBO had lower MBC values when compared to HO (P=0.003). No statistical difference was observed between MSSP/MRSP isolates (HBO P=0.757, HO P=0.743). Only HO was affected by catalase (P=0.015). MFC for HBO was 10% w/v (5-10% w/v) and 40% w/v for HO (20-≥40% w/v). All isolates were killed after 4h of exposure. Staphylococcus pseudintermedius and M.pachydermatis are susceptible to the HBO and these results can be used for future clinical trials.

Readily dispersible antimicrobial Ag–SiO2 Janus particles and their application on cellulosic fabric

Silver–silica (Ag–SiO2) Janus particles with varying functionalities i.e. amine, thiol and epoxy on the exposed surface of SiO2 particles were synthesized and explored for their antimicrobial activity. Due to their easy dispersibility, Janus particles with silver nanoparticles (AgNPs) of diameter ∼3 nm showed much lower minimum bactericidal concentration (MBC) as compared to conventional isotropic AgNPs powder having AgNPs of almost similar diameter. The isotropic AgNPs and functionalized Ag–SiO2 Janus particles were attached on cotton fabric using exhaustion method followed by curing. The treated fabrics were tested for their antimicrobial activity and wash durability. Ag–SiO2 Janus particles, due to the presence of various functionalities on one–half of their surface, could be attached to cellulosic substrates for imparting durable antimicrobial property.

Investigation of antibacterial and anti-cancer activities of Streptomyces sp SRF1 culture filtrate

Purpose: To evaluate the antibacterial activity and cytotoxic effects of Streptomyces sp. SRF1 culture filtrate extract against breast cancer cell line.Methods: The activity of the extract against Gram-positive and Gram-negative bacteria was initially screened by an agar-well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were measured by broth microdilution method. Time-kill assays were also performed, and extract-induced morphological and ultrastructural changes to bacterial cells were investigated. Sulforhodamine B (SRB) assay was performed to determine the cytotoxicity of the extract against the human breast cancer cell line, MCF-7.Results: Antibacterial activity by the extract was detected against four strains of Gram-positive pathogens including one strain of methicillin-susceptible Staphylococcus aureus (MSSA) and 3 strains of methicillin-resistant Staphylococcus aureus (MRSA) - with low MIC and MBC values. This activity was bactericidal after 6 h exposure. Morphological alterations were detected on the cell surface of both MSSA and MRSA. The extract also inhibited MCF-7 cell growth with half-maximal concentration (IC50) of 211.67 ± 33.95 μg/mL in 72 h.Conclusions: Streptomyces sp. SRF1 culture filtrate extract exhibits potent antibacterial and anticancer activities and thus, represents a potential source of antibacterial and anticancer drugs.Keywords: Antibacterial activity, Anti-breast cancer, Staphylococcus aureus, Streptomyces sp. SRF1

Novel Kombucha Beverage from Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum, with Antibacterial and Antioxidant Effects.

Kombucha is a nonalcoholic beverage traditionally made by fermenting black tea using a combination of yeast and acetic acid bacteria (AAB) cultures. Ganoderma lucidum hot water extract (HWE) was used-to our knowledge for the first time-to prepare a novel, health-promoting kombucha product. During the 11-day fermentation, pH, total acidity, and the numbers of yeasts and AAB were monitored. It was found that sweetened G. lucidum HWE was a good medium for yeast and AAB growth. The desired acidity for the beverage was reached on the second day (3 g/L) of the fermentation process; the maximum established acidity was 22.8 ± 0.42 g/L. Fourier transform infrared analysis revealed that the vacuum-dried beverage is a mixture of various compounds such as polysaccharides, phenols, proteins, and lipids. Total phenolic content of the liquid sample was 4.91 ± 0.2338 mg gallic acid equivalents/g, whereas the vacuum-dried sample had a smaller amount of phenolics (2.107 ± 0.228 mg gallic acid equivalents/g). Established half-maximal effective concentrations for DPPH scavenging activity and reducing power were 22.8 ± 0.17 and 10.61 ± 0.34 mg/mL, respectively. The antibacterial testing revealed that activity does not originate solely from synthesized acetic acid. The liquid G. lucidum beverage was the most effective against the tested bacteria, with the lowest minimum inhibitory concentration (0.04 mg/mL) against Staphylococcus epidermidis and Rhodococcus equi, and a minimum bactericidal concentration (0.16 mg/mL) against Bacillus spizizenii, B. cereus, and R. equi. The vacuum-dried sample was less effective, with the lowest minimum bactericidal concentration against the Gram-positive bacteria R. equi (1.875 mg/mL) and against the Gram-negative bacteria Proteus hauseri (30 mg/mL).