Minimum Bacteriocidal Concentration Research Articles

Propolis의 어류 병원성 세균에 대한 in vitro 항균 효과

The present study was to investigate in vitro antimicrobial effects of propolis against six different fish bacterial pathogens, Aeromonas hydrophila, Edwardsiella tarda, Vibrio vulnificus, V. parahaemolyticus, A. salmonicida subsp. masoucida, A. salmonicida subsp. salmonicida) using minimum inhibitory concentration (MIC) and minimum bacteriocidal concentration (MBC) tests. In the results, propolis exhibited antimicrobial activity against all bacteria used in the present study, but there was no marked difference in bacterial species except Vibrio species. Collectively, propolis was thought to be an usefulness antimicrobial substance for controlling bacterial diseases in the fish industry.

English

  The antibacterial activities and preliminary phytochemical screening of ethanolic and aqeous extract of Vernonia amygdalina was performed against clinical isolates obtained from University of Ilorin Teaching Hospital (UITH) which included Escherichia coil, Staphylococcus aureus andPseudomonas aeruginosa. Generally, the ethanol extracts showed more activities than aqueous extracts in both samples. The extracts exhibited antibacterial activity against the test organisms (0.5 to 15.50 mm). The phytochemical screening of Vernonia amydalina showed the presence of tannins, cardiac glycosides, saponins and alkaloids. The minimum inhibitory concentration (MIC) ranged between 25 and 200 mg/ml. V. amydalina exhibited a minimum bacteriocidal concentration (MBC) of 50 mg/ml for P. aeruginosa and 125 mg/ml for S. aureuswhile E. coil was bacteriostastic. The crude extracts exhibited strong potency against the clinical bacteria with P. aeruginosa being the most susceptible. The antibacterial efficacy of the crude extracts is therefore discussed.   Key words: Antimicrobial activity, minimum inhibitory concentration, phytochemical, Vernonia amygdalina

The effects of different concentrations of Alum solutions on Mutans streptococci (in vitro study)

Alum has been used as a treatment medication in cases of oral and gingival ulcers, and also as antiseptic mouthwash. This study aimed to examine the effects of different concentrations of Alum on inhibition zone, viability counts and adherence ability of Mutans streptococci compared with deionized water and chlorhexidine gluconate in vitro. Materials and methods: The study dealt with an in vitro study to establish a concentration of Alum mouthrinse that would have the minimum inhibitory concentration and minimum bacteriocidal concentration. The second part evaluated the anti-adherence ability of the experimental agents. Results: This study found that the antibacterial effect of Alum increases with its concentration from 50 to 10000 PPM but still weaker than 0.1% chlorhexidine gluconate. Only concentrations of 5000 and 10000 PPM showed negative adherence of Mutans streptococci to the tooth surface. Conclusions: This study found that the antibacterial effect of Alum increases with its concentration from 50 to 10000 PPM but still weaker than 0.1% chlorhexidine gluconate. Only concentrations of 5000 and 10000 PPM showed negative adherence of Mutans streptococci to the tooth surface.

Synthesis and in vitro Evaluation of the Antimycobacterial Activity of N-aryl-1,4- dihydropyridine-3,5-dicarboxamides

Dihydropyridines (DHPs) with carboxamides in the 3 and 5 positions show anti-tuberculosis activity. The purpose of the present study was to synthesize new DHPs that would possibly possess anti-tuberculosis activity. So a series of N-aryl-1,4-dihydropyridine-3,5-dicarboxamides (3-38) was prepared. They were screened as antitubercular agents against one type of fast growing Mycobacterium (M. smegmatis). The compounds that passed this first screening were then tested against slow-growing Mycobacterium (BCG). Minimum bacteriocidal concentrations (MBCs) were determined using the agar proportion method. The cytotoxic effect of two active compounds against HeLa cell lines was determined using an MTT assay method. N,N-Bisphenyl-4-[1-(4-fluorobenzyl)-2-methylthioimidazole-5-yl]-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxamide 27 and N,N-bisphenyl-4-[1-(2-chlorobenzyl)-2-methylthioimidazole-5-yl]-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxamide 33 were the most potent compounds tested, showing MBCs of 16 and 32 ?g/ml, respectively. Their activities were comparable to that of isoniazid (32 ?g/ml). In the MTT assay, these two compounds showed moderate toxicity.

Phytochemical screening and antibacterial activity of guiera senegalensis leaf extracts

Aqueous (cold and hot) and methanolic extracts of the leaves of Guierasenegalensis were made and their efficacy studied in vitro against Staphylococcus aureus, Salmonella typhi, Escherichia coli and Streptococcus pyogenes. The minimum inhibitory concentration (MIC) and minimum bacteriocidal concentration (MBC) of the extracts was determined using standard methods. Results obtained showed that all extracts inhibited the growth of Staphylococcus aureus, Salmonella typhi, Escherichia coli at all concentrations, while Streptococcus pyogenes was only inhibited at 250 and 200 mg/ml concentration on some of the extracts. The MICs of the different extracts ranges from 40 to 200 mg/ml, while the MBC gave a range of 20 to 200 mg/ml but varies from one isolate to the other. Phytochemical screening of the powdered form of the leaves of Guiera Senegalensis showed it to contain resins, alkaloids, tannins, saponins, glycosides and terpenes. This study shows that the leaf of Guiera Senegalensis possess antibacterial property.Keywords: Guiera senegalensis, leaves, medicinal plant, antibacterial property

Antibacterial Activity of Synthetic Fire Ant Venom: The Solenopsins and Isosolenopsins

BackgroundWe determined the in vitro activity of 9 synthetic fire ant venom alkaloids (±)-solenopsin A, (2R, 6R)-solenopsin A, (2S, 6S)-solenopsin B, (±)-isosolenopsin A, (2S, 6R)-isosolenopsin A,(2R, 6S)-isosolenopsin A, (±)-isosolenopsin B, (2S, 6R)-isosolenopsin B, and (2R, 6S)-isosolenopsin B against 6 species of bacteria (Streptococcus pneumoniae, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Stenotrophomonas maltophilia, and Pseudomonas aeruginosa). MethodsThe minimum inhibitory concentration and minimum bacteriocidal concentration were determined in accordance with the Clinical Laboratory Standards Institute guidelines. Time kill studies used American Type Culture Collection bacterial isolates tested at 5 times the minimum inhibitory concentration. ResultsNone of the venom alkaloids inhibited E. coli or P. aeruginosa, whereas all the alkaloids inhibited S. pneumoniae. Only 4 alkaloids inhibited S. pneumoniae, S. aureus, and S. maltophilia. Time-kill kinetics indicates that all 4 active alkaloids had bactericidal activity. ConclusionsSpecific isomers of synthetic fire ant venom alkaloids have antibacterial activity against human pathogens.

Evaluation of Securidaca longipenduculata leaf and root extracts for antimicrobial activities

The aqueous, ethanol and methanol extracts of the roots and leaves of Securidaca longipenduculata were studied for their antimicrobial activity against Escherichia coli, Shigella sp. and Salmonella typhi, using the agar gel diffusion method. The phytochemicals present, as well as the minimum inhibition concentration (MIC) and minimum bacteriocidal concentration (MBC) of the extracts were also determined using standard methods. Results obtained indicated that the aqueous root extract was the most potent and had MIC and MBC of 50 and 200 mg/ml, respectively, against Shigella spp and S.typhi. Leaf extracts and methanolic root extracts showed no activity. Differences in the phytochemical composition in the various extracts could be responsible for the different antimicrobial activities. The high antimicrobial activity observed particularly from the aqueous root extract verified the ethno-medical claim of the plant in the treatment of diarrhoea, and could be a source for antimicrobials in the face of increasing drug resistance. Key words: Evaluation, antimicrobial activity, Securidaca longipenduculata.

Induction of enzymes of 2,4-dichlorophenoxyacetate degradation in Burkholderia cepacia 2a and toxicity of metabolic intermediates

Burkholderia cepacia 2a inducibly degraded 2,4-dichlorophenoxyacetate (2,4-D) sequentially via 2,4-dichlorophenol, 3,5-dichlorocatechol, 2,4-dichloromuconate, 2-chloromuconolactone and 2-chloromaleylacetate. Cells grown on nutrient agar or broth grew on 2,4-D-salts only if first passaged on 4-hydroxybenzoate- or succinate-salts agar. Buffered suspensions of 4-hydroxybenzoate-grown cells did not adapt to 2,4-D or 3,5-dichlorocatechol, but responded to 2,4-dichlorophenol at concentrations <0.4 mM. Uptake of 2,4-dichlorophenol by non-induced cells displayed a type S (cooperative uptake) uptake isotherm in which the accelerated uptake of the phenol began before the equivalent of a surface monolayer had been adsorbed, and growth inhibition corresponded with the acquisition of 2.2-fold excess of phenol required for the establishment of the monolayer. No evidence of saturation was seen even at 2 mM 2,4-dichlorophenol, possibly due to absorption by intracellular poly-beta-hydroxybutyrate inclusions. With increasing concentration, 2,4-dichlorophenol caused progressive cell membrane damage and, sequentially, leakage of intracellular K(+), P(i), ribose and material absorbing light at 260 nm (presumed nucleotide cofactors), until at 0.4 mM, protein synthesis and enzyme induction were forestalled. Growth of non-adapted cells was inhibited by 0.35 mM 2,4-dichlorophenol and 0.25 mM 3,5-dichlorocatechol; the corresponding minimum bacteriocidal concentrations were 0.45 and 0.35 mM. Strain 2a grew in chemostat culture on carbon-limited media containing 2,4-D, with an apparent growth yield coefficient of 0.23, and on 2,4-dichlorophenol. Growth on 3,5-dichlorocatechol did not occur without a supplement of succinate, probably due to accumulation of toxic quantities of quinonoid and polymerisation products. Cells grown on these compounds were active towards all three, but not when grown on other substrates. The enzymes of the pathway therefore appeared to be induced by 3,5-dichlorocatechol or some later metabolite. A possible reason is offered for the environmental persistence of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T).

Pretreatment With the Protegrin IB‐367 Affects Gram‐Positive Biofilm and Enhances the Therapeutic Efficacy of Linezolid in Animal Models of Central Venous Catheter Infection

Biofilms play an important role in the pathogenesis of several chronic infections and nosocomial infections related to indwelling medical devices. To assess the efficacy of IB-367 and linezolid (LZD) in the treatment of central venous catheter (CVC) infections using the antibiotic-lock technique, in vitro and in vivo studies were performed. The in vitro antibiotic susceptibility assay for Staphylococcus aureus and Enterococcus faecalis biofilms developed on 96-well polystyrene tissue culture plates was performed to determine the activity of the compounds. Efficacy studies were performed in rat models of Gram-positive CVC infection. Silastic catheters were implanted into the superior cava of adult male Wistar rats. Twenty-four hours after implantation, the catheters were pretreated by filling with IB-367. Thirty minutes later, rats were challenged via the CVC with 1.0 x 10(6) CFU (colony forming units) of S aureus strain diffuse Smith and clinical isolate of slime-producing E faecalis. Administration of LZD into the CVC at a concentration equal to the minimum bacteriocidal concentration observed using adherent cells or at a much higher concentration (1024 microg/mL) began 24 hours later. Both for S aureus and E faecalis, the killing activities of LZD against adherent bacteria were at least 4-fold to 8-fold lower than that against freely growing cells. For both strains, in IB-367-pretreated wells, LZD strongly increases its activity. The in vivo studies showed that when CVCs were pretreated with IB-367, Gram-positive biofilm bacterial load was further decreased to 10(1) CFU/mL and bacteremia was not detected. IB-367 has potential as an adjunctive agent to LZD in the treatment of Gram-positive biofilm infections such as CVC infections.

English

Six plant extracts obtained from different parts such as the leaves, flowers and seeds of four species of the endemic plants in Turkey were tested on a total of 14 microorganisms, 10 of which were bacterial strains and 4 yeast strains.&nbsp;Verbascum eriocarpum&nbsp;(flower) extract was found to be effective against&nbsp;Staphylococcus aureus;Stachys cretica&nbsp;subsp.&nbsp;anatolica&nbsp;(leaf and flower) and&nbsp;Heracleum paphlago-nicum(seed) extracts were found to be effective against&nbsp;Bacillus subtilis; and&nbsp;Alcea apterocarpa&nbsp;(seed and sepal) extract was found to be effective against&nbsp;Pseudomonas aeruginosa. No antimicrobial activity was observed in&nbsp;Heracleum paphlagonicum(leaf) and&nbsp;Alcea apterocarpa&nbsp;(leaf) plant extracts. The minimum inhibitory concentration&shy; (MIC) values of the plant extracts were calculated to be between &ge; 0.859 mg/ml and &ge; 110.5 mg/ml and the minimum bacteriocidal concentration (MBC) values were calculated to be between &ge; 3.44 mg/ml and &ge; 132 mg/ml. &nbsp; Key words:&nbsp;Antimicrobial activity, endemic plants, plant extract.

EVALUATION OF ANTIMICROBIAL ACTIVITY OF WATERY AND ALCOHOLIC EXTRACTS FOR ANCHUSA STRIGOSA ON GROWTH OF GRAM POSITIVE PATHOGENIC BACTERIA ISOLATED FROM PHARYNGITIS AND TONSILLITS CASES

The effects of Anchusa strigosa plant extract were studied in respect totheir of gram positive bacterial growth inhibition. were isolated from cases ofpharyngitis and tonsillitis . alcoholic and hot water extracts of the plants as wellas their dried powders were prepared . The preliminary chemical tests revealedacidic pH of all extracts.The dried powder , watery and alcoholic extracts of A. strigosacontained resins ,tannins , phenols, flavonoids, glycosides and avery littleamount of alkaloids in its watery and alcoholic extract.The alcoholic extract ofA. strigosa showed more patent inhibitory effect on resistant bacteria than itswatery extract and the best effect was on growth of Strept.salivarius andStrept.pyogenes inhibition zone diameter 27.0,26.0 mm. In the present study ,the Minimum inhibitory concentration (MIC) and Minimum bacteriocidalconcentration (MBC) of the plants extracts were measured for the morepredominant gram positive isolates and the results varied according to differentkinds of plant extracts and different types of bacteria . The least values of MICand MBC were for alcoholic extract of A. strigosa on Staph.epidermidis whichvalued 10% ,20% respectively .It has been noticed that the watery extracts of A.strigosa , have a sedative effect when given dosing 5 g/kg for laboratorymice , these extracts however, showed a synergistic sedative effect when mixedwith pentobarbitone and caused prolongation of sleeping time in experimentalmice .Neither the alcoholic nor the watery extracts of the plants showed anytoxic effect on the laboratory mice after oral dosing of 2.5 – 15 g /Kg B.W.Watery and alcoholic extracts, Anchusa strigosa , Pharyngitis ,Tonsillitis .Pathogenic bacteria

Antibacterial Effect of Edible Plant Extract on Escherichia coli 0157:H7

Sixteen preparation of the ethanol and aqueous extracts of four edible plants, Entada africana (bark),Terminalia avicennoides (bark),Mitragyna stipulosa (bark) Lannae acida (stem bark) were screened for their inhibitory effects on ten strains of E coli 0157:H7 (EHEC) using the agar diffusion method. It was shown that ethanol extracts of Entanda africana inhibited all the ten strains used, some extracts showed variable antibacterial activities while some others could not cause any inhibition. The minimum inhibitory concentration (MIC) of the potent extracts ranged from 1.56mg/ml to 50.00mg/ml while the minimum bacteriocidal concentration (MBC) was between 6.25mg/ml to 25.00mg/ml. Pytochemical screening of the extracts revealed that all contained saponin. Some showed presence of tannins and glycosides while alkaloid was not detected in all samples.

Cloning and Characterization of CYP51 from Mycobacterium avium

Mycobacterium avium complex (MAC) causes chronic lung disease in immunocompetent people and disseminated infection in patients with AIDS. MAC is intrinsically resistant to many conventional antimycobacterial agents, it develops drug resistance rapidly to macrolide antibiotics, and patients with MAC infection experience frequent relapses or the inability to completely eradicate the infection with current treatment. Treatment regimens are prolonged and complicated by drug toxicity or intolerances. We sought to identify biochemical pathways in MAC that can serve as targets for novel antimycobacterial treatment. The cytochrome P450 enzyme, CYP51, catalyzes an essential early step in sterol metabolism, removing a methyl group from lanosterol in animals and fungi, or from obtusifoliol in plants. Azoles inhibit CYP51 function, leading to an accumulation of methylated sterol precursors. This perturbation of normal sterol metabolism compromises cell membrane integrity, resulting in growth inhibition or cell death. We have cloned and characterized a CYP51 from MAC that functions as a lanosterol 14alpha-demethylase. We show the direct interactions of azoles with purified MAC-CYP51 by absorbance and electron paramagnetic resonance spectroscopy, and determine the minimum inhibitory concentrations (MICs) of econazole, ketoconazole, itraconazole, fluconazole, and voriconazole against MAC. Furthermore, we demonstrate that econazole has a MIC of 4 mug/ml and a minimum bacteriocidal concentration of 4 mug/ml, whereas ketoconazole has a MIC of 8 mug/ml and a minimum bacteriocidal concentration of 16 mug/ml. Itraconazole, voriconazole, and fluconazole did not inhibit MAC growth to any significant extent.

Adrenomedullin and mucosal defence: interaction between host and microorganism

Many surface epithelial cells express adrenomedullin (AM) and it is postulated that it may have an important protective role. This peptide has many properties in common with other cationic antimicrobial peptides including the human β-defensins. Antimicrobial activity against members of the human skin, oral, respiratory tract and gastric microflora has been demonstrated. Both pathogenic and commensal strains of bacteria are sensitive; Gram-positive and Gram-negative bacteria being equally susceptible. No activity against the yeast Candida albicans was observed. Minimum inhibitory and minimum bacteriocidal concentrations range from 7.75×10 −4 to 12.5 and 0.003 to >25.0 μg ml −1, respectively. On exposure of oral, skin and gastric epithelial cells to whole cells and culture supernatants from bacteria isolated from these sites an increase in AM peptide and gene expression has been observed. No upregulation was detected with C. albicans. In cultured cells and an animal infection model increased AM peptide and gene expression has been demonstrated using immunohistochemical and in situ hybridization techniques. These collective findings suggest that AM represents a new category of antimicrobial peptide, which contributes to the mucosal host defence system.

Antibacterial activity of black myrobalan ( Terminalia chebula Retz) against Helicobacter pylori

The effect of ether, alcoholic and water extracts of black myrobalan ( Teminalia chebula Retz) on Helicobactor pylori were examined using an agar diffusion method on Columbia Agar. Water extracts of black myrobalan showed significant antibacterial activity and had a minimum inhibitory concentration (MIC) and minimum bacteriocidal concentration (MBC) of 125 and 150 mg/l, respectively. The extract was active after autoclaving for 30 min at 121°C. Plant powder (incorporated in agar) gave higher MIC and MBC values (150 and 175 mg/l, respectively). Water extracts of the black myrobalan at a concentration of 1–2.5 mg/ml inhibited urease activity of H. pylori. The results show that black myrobalan extracts contain a heat stable agent(s) with possible therapeutic potential. Other bacterial species were also inhibited by black myrobalan water extracts.

An investigation into the antimicrobial effects of adrenomedullin on members of the skin, oral, respiratory tract and gut microflora.

Adrenomedullin, a novel vasoactive peptide, is known to be expressed by many surface epithelial cells and it was postulated that this peptide may have a protective role. The objective of the study was to assess the antimicrobial activity of adrenomedullin against members of the human skin, oral, respiratory tract and gut microflora using disc diffusion and broth microdilution assays. All strains of bacteria screened in an agar diffusion assay were sensitive; gram-positive and gram-negative bacteria were equally susceptible. No activity against the yeast Candida albicans was observed. In a broth microdilution assay, minimum inhibitory and minimum bacteriocidal concentrations ranged from 7.75 x 10(-1) to 12.5 microg ml(-1) and 0.003 to > 25.0 microg ml(-1), respectively. We propose an antimicrobial role for adrenomedullin. participating in the prevention of local infection, thus contributing to host defence systems.

An investigation into the antimicrobial effects of adrenomedullin on members of the skin, oral, respiratory tract and gut microflora

Adrenomedullin, a novel vasoactive peptide, is known to be expressed by many surface epithelial cells and it was postulated that this peptide may have a protective role. The objective of the study was to assess the antimicrobial activity of adrenomedullin against members of the human skin, oral, respiratory tract and gut microflora using disc diffusion and broth microdilution assays. All strains of bacteria screened in an agar diffusion assay were sensitive; Gram-positive and Gram-negative bacteria were equally susceptible. No activity against the yeast Candida albicans was observed. In a broth microdilution assay, minimum inhibitory and minimum bacteriocidal concentrations ranged from 7.75×10 −4 to 12.5 μg ml −1 and 0.003 to >25.0 μg ml −1, respectively. We propose an antimicrobial role for adrenomedullin, participating in the prevention of local infection, thus contributing to host defence systems.

An evaluation of antibiotics for the elimination ofXanthomonas campestris pv.pelargonii (Brown) fromPelargonium x domesticum cv. ?Grand Slam? explants in vitro

A range of antibiotics was evaluated for activity againstXanthomonas campestris pv.pelargonii (Xep) on diagnostic sensitivity testing and plant tissue culture media. Many of the antibiotics showed reduced or no activity on the latter. Tetracycline and cefotaxime, chosen for further investigation, were screened for light stability under plant culture regimes. Tetracycline was inactivated in photosynthetic photon fluxes of 22 μmol m-2 s-1 and above. The minimum bacteriocidal concentration of cefotaxime was determined in bacteriological and plant tissue culture media. Cefotaxime was further tested for phytoxicity and ability to eliminate Xcp from deliberately infected explants. Cefotaxime was shown to eliminate contamination and stimulate the growth of the plant tissue cultures up 500 mg l-1.

RATIONAL CHOICE OF PENICILLINS AND CEPHALOSPORINS BASED ON PARALLEL IN-VITRO AND IN-VTVO TESTS

Because of the unavailability of strictly comparable data, seven representative penicillins and the five cephalosporins currently used in Britain were evaluated in parallel, both in vitro and in vivo. Penicillin sensitive and resistant strains of Staphylococcus aureus and Proteus mirabilis were the main test organisms. Minimum bacteriocidal concentrations of cloxacillin, flucloxacillin, cephalothin, and cephazolin in serum were much higher than conventional minimum inhibitory concentrations in the absence of serum, Cephalexin and cephradine showed the smallest divergence in these values. Staph. aureus β-lactamase caused least damage to methicillin and cephradine, whereas enzymes from Escherichia, Klebsiella, and Bacillus cereus had least effect against cephradine followed by cephalexin. In mouse protection experiments, highly protein-bound antibiotics had relatively low efficacy Cephradine had the highest mean activity followed closely by cephaloridine and cephalexin. From the data cephradine was the cephalosporin of choice, and firm decisions were also made about the choice of penicillins.