Dependent Antibacterial Activity Research Articles

Anti-inflammatory and antibacterial activities of Lippia nodiflora and its effect on blood clotting time

Aqueous extract of Lippia nodiflora possessed anti-inflammatory activity in Carrageenan induced mice paw edema in both doses 100 and 200 mg /kg bw (P< 0.01). However, the ethanolic extracts didn’t induced anti-inflammatory effects in both doses. Aqueous extract of Lippia nodiflora exerted a concentration – dependent antibacterial activity against E.coli but not effective against Staphylococcus aureus and Pseudomonas aeruginosa. Ethanolic extract possessed antibacterial activity against gram positive (Staphylococcus aureus) and gram negative (E. coli) but not effective against Pseudomonas aeruginosa. Ethanolic extract of Lippia nodiflora significantly hasten blood clotting when used in a dose of 100 mg/kg (P< 0.05) and 200 mg /kg (P< 0.01). The effect of the ethanolic extract appeared dose dependent. However, aqueous extract didn’t exerted significant effects on blood clotting time in both doses used in this sTUDY

Anti-Yersinia Activity of Cryptdin-2: A Paneth Cell Peptide

In view of the emerging antibiotic(s) resistance in pathogens, there is a renewed interest in clinical medicine to exploit novel agents with a wide range of actions over several pathogens. Therefore, in the present study, bactericidal efficacy of cryptdin-2 against Yersinia enterocolitica was evaluated. Cryptdin-2 exhibited strong bactericidal activity against Y. enterocolitica at the minimum bactericidal concentration (MBC) of 21 μg/ml. Scanning electron microscopic investigations of cryptdin-2 treated bacterial cells revealed that the peptide was able to induce significant morphological alterations in terms of destructive pore formation and damaged membrane confirming its membrane dependent bactericidal activity. N-phenyl napthylamine (NPN) uptake assay in the presence of sublethal, lethal as well as twice the lethal concentrations further confirmed the membrane-dependent mode of action of cryptdin-2 which indicated that the peptide could permeabilize the membrane of Y. enterocolitica. Additionally, the peptide interfered with DNA, RNA as well as protein synthesis in Y. enterocolitica, with maximum inhibition observed for protein synthesis. Thus, the biochemical and biophysical alterations observed in the treated cells in terms of macromolecular synthesis and membrane permeabilization respectively, correlated well with the bactericidal activity. In view of the antibacterial efficacy of the peptide against Salmonella typhimurium and Entamoeba histolytica, observed in our earlier studies, along with its inhibitory potential against Y. enterocolitica as demonstrated in the present study, suggests that it may be exploited as a broad-spectrum antimicrobial agent against enteric infections.

Synthesis and concentration dependent antibacterial activities of CuO nanoflakes

We report, synthesis and antibacterial activities of CuO nanoflakes. CuO nanoparticles are prepared at room temperature through sol–gel method. X-ray diffraction studies show the particles are monoclinic (crystalline) in nature. Scanning electron microscopy (SEM) images clearly show that the prepared particles are flake like in structure. Fourier transform infrared (FTIR) spectra exhibits three different bands that correspond to the Au and Bu modes. Antibacterial studies were performed on Shigella flexneri, Staphylococcus aureus, Staphylococcus epidermidis, Salmonella typhimurium, Bacillus subtilis, Escherichia coli, Vibrio cholera, Pseudomonas aeruginosa and Aeromonas liquefaciens bacterial strains. Among these bacterial strains, S. flexneri and B. subtilis are most sensitive to copper oxide nanoparticles than the positive control (Penicillin G) and S. typhimurium strain shows the less sensitive. Results show that sensitivity is highly dependent on the concentrations of CuO nanoflakes.

Antibacterial Action of Haw Pectic Oligosaccharides

Haw pectic oligosaccharides, lactic acid, sodium lactate, and tea polyphenol showed dose and pH dependent antibacterial activity against E. coli. The activity of haw pectic oligosaccharides could be enhanced by combination with lactic acid, sodium lactate, or tea polyphenol. However, combination of haw pectic oligosaccharides with nisin resulted in no significant enhancement of antibacterial activity against E. coli. These results revealed that haw pectic oligosaccharides is valuable as a food preservative, and lactic acid or sodium lactate could be used to enhance its antibacterial activity, allowing for further improvement in its efficiency, likely leading to a reduction in the dosage necessary for food preservation.

Evaluation of the combined antimicrobial activity of the leaf extract of phyllantus muellerianus with ciprofloxacin

Background: Infectious diseases caused by multi-resistant microbial strains are on the increase. Fighting these diseases with natural products may be more efficacious. The aim of this study was to investigate the in vitro antimicrobial activity of methanol leaf extract and chromatographic fractions of the extract of Phyllanthus muellerianus (Kuntze) Excell against Klebsiella spp., Enterococcus faecalis, Pseudomonas earuginosa, Proteus mirabilis, Escherichia coli, Salmonella spp. and Candida albicans. The combined effect of the extract or its fractions with ciprofloxacin was also tested. Methods: The antimicrobial properties of the methanol extract of P. muellerianus and its fractions were determined in vitro using the agar diffusion method. Agar diffusion Checkerboard method and Overlay Inoculum susceptibility disc method were used to study the interaction of the extract or fraction with ciprofloxacin. The extract was subjected to phytochemical analysis for identification of constituents using standard procedures. The minimum inhibitory concentration (MIC) data obtained from the antimicrobial studies were analyzed for significant difference at p<0.05 using one way analysis of variance (ANOVA). Results: While n-hexane and methylene chloride fractions showed no activity against the test microorganisms, methanol crude extract and methanol fraction of the extract revealed a good concentration dependent antibacterial activity against P. earuginosa, P. mirabilis and E. faecalis. Combinations of the extract and ciprofloxacin produced antagonistic effect against P. mirabilis and E. faecalis while a synergistic effect was obtained against P. aeruginosa . The results of the phytochemical screening showed that the extract and the fractions contain glycosides, flavoniods, saponins, alkaloids. Conclusion: The methanol leaf extract of Phyllanthus muellerianus possess antibacterial activity against P. earuginosa, P. mirabilis and E. faecalis and could possibly be used in combination with ciprofloxacin to treat infections caused by P. aeruginosa.

Bactericidal activity of starch-encapsulated gold nanoparticles

We report the bactericidal applications of eco-friendly starch encapsulated gold nanoparticles (St-AuNPs). The mechanism of interaction of the properly characterized St-AuNPs with both Gram negative and Gram positive bacteria were investigated using spread plate assay, transmission electron microscopy (TEM), and fluorescent propidium iodide (PI) exclusion assay. The St-AuNPs were found to possess significant dose dependent antibacterial activity against both types of bacteria. St-AuNPs at 1.2 mg/mL caused 98 % eradication of Gram positive bacteria that was exposed over a period of 12 h. Similarly, 4.8 mg/mL St-AuNPs caused 98 % eradication of Gram negative bacteria over a period of 12h. The St-AuNPs are biocompatible and present a useful solid porous carbohydrate-based polymer vehicle with excellent antimicrobial activity against [Frontiers in Bioscience 18, 982-992, June 1, 2013].

Antibacterial Activities of the Combined Leaf Extract of Phyllanthus muellerianus and Ciprofloxacin against Urogenital Isolates of Staphylococcus aureus

Infectious diseases caused by multi-resistant strains of Staphylococcus aureus are on the increase and fighting them with natural products may be more efficacious. The aim of this study was to investigate the in vitro antibacterial activity of methanol leaf extract and the solvent fractions of Phyllanthus muellerianus (Kuntze) Excell as well as their combinations with ciprofloxacin against various isolates of Staphylococcus aureus. Phytochemical screening was done following established method while the in vitro antimicrobial properties of the extract and fractions of the extract were investigated by the agar diffusion method. Agar diffusion Checkerboard and Overlay Inoculum susceptibility disc methods were further employed to study the interaction of the extract, fraction and ciprofloxacin against eight (8) isolates of S. aureus. Results showed that the extract and the fractions contain glycosides, flavonoids, saponins and alkaloids. N- Hexane and methylene chloride fractions showed no activity against the test microorganisms, while methanol fraction and methanol crude extract produced a concentration dependent antibacterial activity against the organisms. Result of interaction study revealed synergism in some of the combination ratios but the predominant effects were indifference and antagonism. The study has demonstrated that the leaf extract and the polar fraction of the plant, P. muellerianus, possess potent antibacterial effect against various strains of S. aureus. Combination of the extract or the fraction with ciprofloxacin could be beneficial in treating infections caused by S. aureus.

ANTI-BACTERIAL ACTIVITY OF ROOT EXTRACT OF ACONITUM HETEROPHYLLUM AGAINST SOME PATHOGENIC BACTERIA

Aqueous and ethanol extracts of Aconitum heterophyllum on five test bacteria such as (Bacillus cereus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas fluorescences and Staphylococcus faecalis) exhibited concentration dependent antibacterial activity. All fractions showed a promising activity towards Escherichia coli, Klebsiella pneumoniae, Pseudomonas fluorescences and Staphylococcus faecalis, however less inhibition was observed in Bacillus cereus. Similarly when compared to aqueous root extract, ethanol root extract showed maximum activity against all the tested organisms.

In vitro activities of antimicrobial cationic peptides; melittin and nisin, alone or in combination with antibiotics against Gram-positive bacteria

The in vitro activities of two antimicrobial cationic peptides, melittin and nisin alone and in combination with frequently used antibiotics (daptomycin, vancomycin, linezolid, ampicillin, and erythromycin), were assessed against clinical isolates of methicillin-susceptible Staphylococcus aureus, methicillin-resistant S. aureus and Enterococcus faecalis. Using the broth microdilution method, minimum inhibitory concentration (MIC) ranges of melittin and nisin against all strains were 2–8 μg/ml and 2–32 μg/ml respectively. In combination studies performed with the microdilution checkerboard method using a fractional inhibitory concentration index of ⩽0·5 as borderline, synergistic interactions occurred more frequently with nisin–ampicillin combination against MSSA and nisin–daptomycin combination against E. faecalis strains. The results of the time-killing curve analysis demonstrated that the concentration dependent rapid bactericidal activity of nisin, and that synergism or early synergism was detected in most strains when nisin or melittin was used in combination with antibiotics even at concentrations of 0·5×MIC.

In vitro antimicrobial potential of Terminalia chebula fruit extracts against multidrug–resistant uropathogens

ObjectiveTerminalia chebula Retz. (combretaceae) is called the “King of Medicine” in Tibet and is always listed at the top of the list of “Ayurvedic Materia Medica” because of its extraordinary power of healing. The present study was carried out to evaluate the possible in vitro antibacterial potential of different solvent extracts of T. chebula fruit against multidrug–resistant uropathogens. MethodsA total of 52 multidrug–resistant uropathogenic bacteria were used in this study. Successive extractions of T. chebula fruits were performed with solvents of different polarities. Agar well diffusion and microbroth dilution assay methods were used for antibacterial susceptibility testing. Kill-kinetics study was done to know the rate and extent of bacterial killing. Qualitative phytochemical screening was done to know the major phytoconstituents present in the plant material. Acute oral toxicity study in mice was performed to evaluate the toxic potential of the plant material, if any. ResultsThe ethanol extract of T. chebula fruits demonstrated a strong antimicrobial activity against all the test isolates and found to be most effective over others. Kill-kinetics study showed dose and time dependent antibacterial activity of ethanol extract. Phytochemical analysis revealed the presence of high concentration of phenolics and low concentration of flavonoids and terpenoids. In acute oral toxicity study, no gross behavioral changes were observed in mice at recommended dosage level and 24 h LD50 of ethanol extract was found to be >4 g/kg, p.o. in mice. ConclusionsThe results provide justification for the use of Terminalia chebula fruit in folk medicine to treat various infectious diseases and could be useful for the development of alternative/complementary medicine for multidrug–resistant uropathogens.

Enhancement of Lactic Acid on Antibacterial Activity of Haw Pectic Oligosaccharides

The enhancive effects of lactic acid on the antibacterial activities of haw pectic oligosaccharides (HPOS) against the Gram positive bacteria Staphylococcus aureus, Bacillus subtilis and Streptococcus faecalis, were investigated. Both HPOS and lactic acid showed dose and pH dependent antibacterial activity against S. aureus and B. subtilis. S. faecalis was sensitive to the HPOS but was resistant to the lactic acid. The antibacterial activity of HPOS against these three bacteria could be enhanced by co-treatment with lactic acid. The results revealed that HPOS may be useful as a food preservative, and lactic acid was able to enhance the antibacterial activity of HPOS, allowing for a further improvement in its efficiency. This additive effect obtained with lactic acid would likely result in a reduction in the dosage necessary for food preservation.

Mutant-prevention concentration and mechanism of resistance in clinical isolates and enrofloxacin/marbofloxacin-selected mutants of Escherichia coli of canine origin

The antibacterial activity and selection of resistant bacteria, along with mechanisms of fluoroquinolone resistance, were investigated by integrating the static [MIC or mutant-prevention concentration (MPC)] and in vitro dynamic model approaches using Escherichia coli isolates from diseased dogs. Using the dynamic models, selected E. coli strains and enrofloxacin and marbofloxacin at a range of simulated area under concentration-time curve over a 24 h interval (AUC(24 h))/MIC ratios were investigated. Our results indicated increasing losses in susceptibility of E. coli upon continuous exposure to enrofloxacin and marbofloxacin in vitro. This effect was transferable to other fluoroquinolones, as well as to structurally unrelated drugs. Our results also confirmed an AUC(24 h)/MIC (AUC(24 h)/MPC)-dependent antibacterial activity and selection of resistant E. coli mutants, in which maximum losses in fluoroquinolone susceptibility occurred at simulated AUC(24 h)/MIC ratios of 40-60. AUC(24 h)/MPC ratios of 39 (enrofloxacin) and 32 (marbofloxacin) were considered protective against the selection of resistant mutants of E. coli. Integrating our MIC and MPC data with published pharmacokinetic information in dogs revealed a better effect of the conventional dosing regimen of marbofloxacin than that of enrofloxacin in restricting the selection of resistant mutants of E. coli. Target mutations, especially at codon 83 (serine to leucine) of gyrA, and overexpression of efflux pumps contributed to resistance development in both clinically resistant and in vitro-selected mutants of E. coli. We also report here a previously undescribed mutation at codon 116 of parC in two laboratory-derived resistant mutants of E. coli. Additional studies would determine the exact role of this mutation in fluoroquinolone susceptibility, as well as establish the importance of our findings in the clinical setting.

Phytochemical screening and antibacterial activity of leaf extracts of &lt;i&gt;Senna siamea&lt;/i&gt; (LAM) on &lt;i&gt;Pseudomonas aeruginosa&lt;/i&gt;

The anti-pseudomonal activities of aqueous, chloroform and ethanolic extracts of leaf of Senna siamea (LAM) were evaluated by agar disc diffusion method. This was with the aim of substantiating the ethnomedicinal use of the plant as anti-bacterial. All the extracts were not active to Ps. aeruginosa at the concentration levels of 100μg/disc and 200μg/disc, however the extracts were active at high concentration levels of 500μg/disc and 1000μ/disc revealing a dose – dependent antibacterial activity. Aqueous extract was the most active with zone diameter of inhibitions of 16mm and 30mm followed by ethanolic extract which had zones of inhibition of 10mm and 16mm and the least was chloroform extract which has zone diameter of inhibitions of 08mm and 14mm, all at 500μg/disc and 1000μg/disc concentrations respectively. Ciprofloxacin (oxoid) as positive control had zone diameter of inhibition of 35mm in all the test plates. The antipsedomonal potential of the leaves of Senna siamea Lam leaf may be due to the phytochemical compounds present in the leaf extracts, which were found to be tannins, saponnins and steroids. However aqueous extract proved to be a more suitable candidate for use in the treatment of diseases cause by Pseudomonas aeruginosa. Hence, antimicrobial evaluation and biotechnological study of the whole plant are thus recommended. Keywords: Antipseudomonal, Senna siamea, Phytochemicals. Screening, Pseudomonas aeruginosa

Synthesis of ZnO nanoparticles and study of their antibacterial and antifungal properties

In this paper, ZnO nanoparticles have been synthesized with and without the use of surfactants under different reaction conditions. The size of the ZnO nanoparticles varied in diameter (2 nm–28 nm) according to the reaction conditions employed. Promising particle size dependent antibacterial and antifungal activities of the ZnO nanoparticles have been observed. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Infrared spectroscopy (FTIR) techniques were used to characterize the particle size and morphology.

Proximate Composition, Antibacterial and Anthelmintic Activity of Capsicum frutescens (L.) Var. Longa (Solanaceae) Leaves

Introduction:Capsicum frutescens (L.) var. longum (Solanaceae) is a well used tropical and subtropical medicinal plant. The present study was undertaken to investigate proximate composition, antibacterial and anthelmintic activity of C. frutescens leaves.Methods: The leaf material was tested for proximate parameters namely carbohydrates, proteins, crude fibre, crude fat, ash and moisture. The powdered leaf material was extracted using methanol. Antibacterial activity of the methanolic extract was tested by agar well diffusion method. Anthelmintic activity of the methanolic extract was studied using Indian earthworm.Results: The protein, ash, crude fat and crude fibre contents were not appreciably high. The carbohydrate content was comparatively higher. Among microelements, iron was found to be in high concentration. Potassium content was found to be high than phosphorus. The methanolic extract showed dose dependent antibacterial and anthelmintic activity. Among the bacteria studied, S. aureus was found to be more susceptible to the methanolic extract followed by K. pneumoniae and P. aeruginosa. The anthelmintic effect of all concentrations was lesser when compared to standard. Phytochemical analysis revealed saponins, tannins, alkaloids, glycosides and steroids in methanol extract.Conclusion: The leaves may be used as a good source of carbohydrates and other nutrients. The methanolic extract could be used in the treatment of bacterial and helmintic infections. The presence of various phytochemicals might be responsible for the biological potential of the extract. Further studies on isolation of constituents from the extract and their biological activities are under investigation.

Pharmacotherapy Update: Daptomycin in the Management of Complicated Skin and Soft-tissue Infections

Because of the dramatic increase in severe infections caused methicillin-resistant Staphylococcus aureus (MRSA), including skin and skin structure infections (SSSI), and reports of vancomycin failures in the treatment of these infections, agents with better activity against MRSA are clearly needed. Daptomycin, the first cyclic lipopeptide, exerts its concentration dependent bactericidal activity against S. aureus through a calcium dependent formation of channels leading to disruption of the bacterial cell membrane potential. Daptomycin is 90% protein bound, has a half-life of 8–9 h, is eliminated through renal excretion, and has a good penetration into inflammatory skin blisters. This compound was shown to be non-inferior to the comparator in two double-blind randomized phase III studies including patients with complicated SSSI, using a dose of 4 mg/kg/day. In these studies, cure rates in the clinical and microbiology evaluable populations were 83.4% and 84.2% (95% CI, -4 to 5.6), and 84.7% and 85.9% (95% CI, -3.8 to 6.3) for daptomycin and comparator, respectively. Daptomycin also showed efficacy in prospective studies in patients with infective cellulitis or erysipelas, necrotizing soft tissue infection, and infected diabetic foot ulcers. Even though the standard dose of 4 mg/kg/day is considered appropriate for most SSSI, higher doses (e.g. 6 to 10 mg/kg/day) are currently suggested for patients with sepsis, necrotizing infection, prior glycopeptide failure, infections caused by vancomycin intermediate S. aureus (VISA) strains, renal insufficiency, burns, and in intravenous drug users. Overall, daptomycin is considered a well tolerated antibiotic. In clinical trials, drug discontinuation rate has been similar in patients receiving daptomycin compared with those treated with the comparators; however, muscular damage associated with increased serum creatine phopshokinase levels occurs in about 3% and 7% of the patients treated with 4 and 6 mg/kg/day, respectively. This reversible muscle toxicity appears to correlate with the daptomycin trough concentration and time of exposure.

In vitro Antibacterial and Morphological Effects of the Urushiol Component of the Sap of the Korean lacquer tree (Rhus verniciferaStokes) onHelicobacter pylori

Eradication regimens for Helicobacter pylori infection have some side effects, compliance problems, relapses, and antibiotic resistance. Therefore, alternative anti-H. pylori or supportive antimicrobial agents with fewer disadvantages are necessary for the treatment of H. pylori. We investigated the pH-(5.0, 6.0, 7.0, 8.0, 9.0, and 10.0) and concentration (0.032, 0.064, 0.128, 0.256, 0.514, and 1.024 mg/mL)-dependent antibacterial activity of crude urushiol extract from the sap of the Korean lacquer tree (Rhus vernicifera Stokes) against 3 strains (NCTC11637, 69, and 219) of H. pylori by the agar dilution method. In addition, the serial (before incubation, 3, 6, and 10 min after incubation) morphological effects of urushiol on H. pylori were examined by electron microscopy. All strains survived only within pH 6.0-9.0. The minimal inhibitory concentrations of the extract against strains ranged from 0.064 mg/mL to 0.256 mg/mL. Urushiol caused mainly separation of the membrane, vacuolization, and lysis of H. pylori. Interestingly, these changes were observed within 10 min following incubation with the 1×minimal inhibitory concentrations of urushiol. The results of this work suggest that urushiol has potential as a rapid therapeutic against H. pylori infection by disrupting the bacterial cell membrane.

Phytoconstituents and biological activities of essential Oil from Rhus lancea L. F

The present study determined the major phytoconstituents, the antioxidant and the antimicrobial activities of Rhus lancea essential oil against eight bacterial and four fungal species. The yield was 0.18% and the major phytoconstituents found were µ-pinene, benzene and d-3-carene. The oil exhibited remarkable anti-oxidant and dose dependent antibacterial and antifungal activities with highest activities against Escherichia coli, Clostridium perfringens and Aspergillus flavus. To the best of our knowledge this is the first report on the antimicrobial activity of the essential oils from this plant. Further studies are warranted to test the toxicity and the suitability of this essential oil for pharmaceutical and other uses.

Heteroatom-Containing Antibacterial Phenolic Metabolites from a TerrestrialAmpelomycesFungus

Two new sulfur-containing phenolic compounds, 7-hydroxy-5-hydroxymethyl-2H-benzo[1,4]thiazin-3-one (1) and 2,5-dihydroxy-3-methanesulfinylbenzyl alcohol (2), along with two known compounds, 3-chloro-2,5-dihydroxybenzyl alcohol (3) and 2-hydroxy-6-methylbenzoic acid (4), were isolated from the mycelial solid culture of a soil-derived Ampelomyces fungus by antibacterial assay-guided fractionation. Their structures were elucidated on the basis of spectroscopic analysis. Compounds 1-3 showed structure and microbial dependent antibacterial activities.

Human Peptidoglycan Recognition Proteins Require Zinc to Kill Both Gram-Positive and Gram-Negative Bacteria and Are Synergistic with Antibacterial Peptides

Mammals have four peptidoglycan recognition proteins (PGRPs or PGLYRPs), which are secreted innate immunity pattern recognition molecules with effector functions. In this study, we demonstrate that human PGLYRP-1, PGLYRP-3, PGLYRP-4, and PGLYRP-3:4 have Zn(2+)-dependent bactericidal activity against both Gram-positive and Gram-negative bacteria at physiologic Zn(2+) concentrations found in serum, sweat, saliva, and other body fluids. The requirement for Zn(2+) can only be partially replaced by Ca(2+) for killing of Gram-positive bacteria but not for killing of Gram-negative bacteria. The bactericidal activity of PGLYRPs is salt insensitive and requires N-glycosylation of PGLYRPs. The LD(99) of PGLYRPs for Gram-positive and Gram-negative bacteria is 0.3-1.7 muM, and killing of bacteria by PGLYRPs, in contrast to killing by antibacterial peptides, does not involve permeabilization of cytoplasmic membrane. PGLYRPs and antibacterial peptides (phospholipase A(2), alpha- and beta-defensins, and bactericidal permeability-increasing protein), at subbactericidal concentrations, synergistically kill Gram-positive and Gram-negative bacteria. These results demonstrate that PGLYRPs are a novel class of recognition and effector molecules with broad Zn(2+)-dependent bactericidal activity against both Gram-positive and Gram-negative bacteria that are synergistic with antibacterial peptides.