Tube Dilution Research Articles

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IntroductionEnterococci are part of the normal intestinal flora of humans and animals but have also emerged as important pathogens responsible for serious infections in hospital and community acquired infections. According to recent surveys, Enterococci remain in the top 3 most common pathogens that cause nosocomial infections. AimTo process all the clinical samples from various departments in our hospital, for the isolation of Enterococci sp. To speciate the isolates & to have the resistance pattern of the isolates to Vancomycin Methods and MaterialA total of 928 samples were collected from both out patients and in patients in all clinical departments and transported to microbiology laboratory. Specimens were processed by inoculating on to Mac Conkeys agar, blood agar, nutrient agar and Pfizer selective media and incubated at 370C for 24 48 hours. Enterococci were identified by their typical arrangement in Gram stain, Bile esculin test and salt tolerance test. Speciation was done by subjecting the isolates to a battery of biochemical tests. Antimicrobial susceptibility patterns were determined by performing Kirby-Bauer disc diffusion method and Minimum Inhibitory Concentration (MIC) values were identified by Tube & Agar dilution method. ResultsA total of 928 samples. Among these, 647 (69.72%) were culture positive with different isolates and 281 (30.28%) were culture negative. Among 647 culture positive cases, 100 (15.46%) were Enterococcus faecalis. Antimicrobial susceptibility & MIC done as per standard protocols. The E. Faecalis showed 99% sensitive to Vancomycin. The resistance to Vancomycin was further confirmed by MIC both Agar &Tube dilution methods, in which the MIC was: 32μg/ml in one isolate. ConclusionsSpecies level identification of Enterococcus is not only important for epidemiological study, but also for analysing the drug resistant pattern. Effective detection of Vancomycin resistance in laboratory helps in reducing the morbidity and mortality due to VRE in hospitalized patients. Key wordsBlood agar, Mac Conkeys agar, Bile esculin, Vancomycin resistant Enterococci, Minimum inhibitory concentration. International Journal of Medical and Clinical Research ISSN:0976-5530 & E-ISSN:0976-5549, Volume 3, Issue 4, 2012 Citation: Sunilkumar Jada and Karthika Jayakumar (2012) Prevalence of Enterococcus species from various clinical specimens in Shri Sathya Sai Medical College & Research Institute with special reference to speciation and their resistance to Vancomycin. International Journal of Medical and Clinical Research, ISSN:0976-5530 & E-ISSN:0976-5549, Volume 3, Issue 4, pp.-154-160. Copyright: Copyright©2012 Sunilkumar Jada and Karthika Jayakumar. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited. Introduction Enterococci are part of the normal intestinal flora of humans and animals but have also emerged as important pathogens responsible for serious infections in hospital and community acquired infections. The genus Enterococcus includes more than 17 species, but only a few cause clinical infections in humans [1]. Enterococci were originally classified as enteric gram-positive cocci and later included in the genus Streptococcus. In the 1930s, with the establishment of the Lancefield serological typing system, Enterococci were classified as group D streptococci and were differentiated from the non-Enterococcal group D streptococci such as Streptococcus bovis by distinctive biochemical

Effect of nalidixic acid on the morphology and protein expression of Pseudomonas aeruginosa

ObjectiveTo determine the effect of nalidixic acid on the morphology and protein expression of Pseudomonas aeruginosa (P. aeruginosa). MethodsNalidixic acid solution of 1 600 μg/mL was prepared. The minimum inhibitory concentration (MIC) for P. aeruginosa was determined with tube dilution test. The effect of nalidixic acid on the morphology of P. aeruginosa was studied using light microscope and scanning electron microscope. Changes in protein profile were studied using SDS-PAGE. ResultsThe MIC of nalidixic acid was 700 μg/mL against P. aeruginosa. The exposure of P. aeruginosa to different concentrations of nalidixic acid resulted in deformation of most of the growing cells. At the concentration of 600 μg/mL most of the cells turned into elongated and adhere to each other while some of the cells were bulged. The intensity of protein bands were changed when they exposed to nalidixic acid. ConclusionsThe present findings suggest that the morphology and protein expression of P. aeruginosa is greatly affected by nalidixic acid.

Effective Value of the Dynamic Dilution Exponent in Bidisperse Linear Polymers: From 1 to 4/3

We revisit previously published dielectric and viscoelastic data of binary blends of linear cis-polyisoprene [Watanabe, H.; Ishida, S.; Matsumiya, Y.; Inoue, T. Macromolecules2004, 37, 6619] in order to test the validity of the dynamic tube dilution (DTD) picture and to determine the most appropriate value of the dilution exponent α. We conclude that the DTD picture with α = 1 is more appropriate at short times, while at longer time, a larger exponent of α = 4/3 gives a better description of the experiments. Furthermore, between these two time regions, a broad crossover zone is found, going from an effective α = 1 to an effective α = 4/3. On the basis of this result, we propose to consider a new relaxation process, which is combined with the classical DTD picture with α = 1 to give the experimentally observed effective α = 4/3 at long times. This extra relaxation process results from the tension equilibration along the long chains, which takes place thanks to the blinking feature of release/reformation of...

Research on the antibacterial effect of fresh pepper leaves

Objective To explore whether fresh pepper leaves have antibacterial activity or not in vitro test and to make clear their inhibition degree.Methods To detect the inhibitory effect and the minimal inhibitory concentration of fresh pepper leaves in vitro by agar disk diffusion method and tube dilution method.Results There was bacterial growth phenomenon in all of the reaction tubes of staphylococcus saprophyticus and no inhibitory effects on agar disk.Significant inhibitory phenomenon both on agar disks and in more than two reaction tubes of Staphylococcus aureus,Staphylococcus epidermidis,Escherichia coli,Proteus vulgaris,Shigella and Haemophilus influenzae was observed.Conclusion Fresh pepper leaves had obvious inhibitory effect for the growth of common intestinal bacteria,pyogenic cocci,especially for Haemophilus influenzae. Key words: Pepper leaves; Minimum inhibitory concentration

Antibacterial Activity of Cacao (Theobroma Cacao Linn.) Pulp Crude Extract Against Selected Bacterial Isolates

Cacao (Theobroma cacao Linn.), a plant with great perennial leaves and yellow or reddish flowers is reported to be antiseptic, diuretic, ecbolic (promotes labor by stimulating uterine contractions), emmenagogue (promotes or stimulates menstrual flow), and parasiticide, Cacao is a folk remedy for alopecia, burns, cough, dry lips, eyes, fever, listlessness, malaria, nephrosis, parturition, pregnancy, rheumatism, snakebite, and wounds. With its wide range of medicinal values, its activity against selected bacterial isolates will be determined in order to find alternative substances that will prevent the widespread of bacterial infection. This study used the experimental research method to determine the antibacterial activity of cacao (Theobroma cacao Linn.) pulp crude extract against selected bacterial isolates including Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 using the paper disc diffusion method. The Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and the biological stability of cacao against the test microorganisms were also determined using the tube dilution method. Stability tests were also performed such as the detemination of the effects of pH and temperature on the activity of cacao against bacterial isolates. Keywords - Cacao, Theobroma cacao, Bacterial Isolates

Antileptospiral, Antioxidant and DNA damaging properties of Eclipta alba and Phyllanthus amarus

Leptospirosis is globally important disease affecting almost all mammals including human being. Several cases of this disease occur in India every year and studies have made to trace the epidemiology, pathology of this disease. It occurs in urban environments of industrialized and developing countries, as well as in rural regions worldwide. The disease is found mainly wherever human come in contact with the urine of infected animals and urine contaminated environment. The unsuccessful attempts to control this disease by chemo therapeutics prompted us to go for alternative control strategies. The present study comprises the use of traditional medicines to overcome the side effects caused by chemotherapeutics. In the present study an attempt has been made to use the herbal medicine to cure leptospirosis either by direct killing or by inhibiting the growth of leptospira. Inhibition of growth has been realized as unique approach to stop the growth. A methonolic and aqueous extract of whole plants of Eclipta alba and Phyllanthus amarus assessed to determine the mechanism(s) of its antileptospiral and antioxidant activity. In this study the antioxidant activity and radical scavenging activity of methanolic and aqueous extracts of selected plant materials were evaluated against 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical and 2,2’azinobis(3-ethylbenzthiazoline- 6-sulfonic acid) (ABTS) activity. DNA damaging studies on leptospira were also investigated. Finally, extracts were tested in different concentration in their respective solvent systems by Tube Dilution Technique (TDT) and Micro Dilution Technique (MDT) tests. The antileptospiral activity of Eclipta alba and P. amarus were studied by both tube dilution and micro dilution techniques and the results showed better inhibitory action against various serogroups of Leptospira. DPPH free radical scavenging effect of extract was compared with standard antioxidant ascorbic acid. IC 50 value was found 75µg/ml for extract and 45µg /ml for ascorbic acid and the methanol extracts of both plants had good activity and IC 50 value was found 55µg/ml and 30µg/ml in ABTS assay. The plant extracts were also found to be very effective against leptospirosis. The possible use of E.alba and P.amarus extracts to control Leptospirosis are discussed in the present studies.

Inhibitory effect of essential oils against Trichosporon ovoides causing Piedra Hair Infection.

Piedra, is an asymptomatic fungal infection of the hair shaft, resulting in the formation of nodules of different hardness on the infected hair. The infection also known as Trichomycosis nodularis is a superficial fungal infection arising from the pathogen being restricted to the stratum corneum with little or no tissue reaction. The nodules are a concretion of hyphae and fruiting bodies of the fungus. Two varieties of Piedra may be seen, Black Piedra and White Piedra. The fungus Trichosporon ovoides is involved in the occurrence of both types of Piedras. The purpose of this study was to examine the effectiveness of selected essential oils for the control of growth of the fungus and to determine whether the antifungal effect was due to the major compounds of the oils. Two screening methods viz. Agar well diffusion assay and Minimum Inhibitory Concentration were adopted for the study. MIC and MFC were determined by tube dilution method. Essential oils from Eucalyptus, Ocimum basilicum, Mentha piperita, Cymbopogon flexuosus, Cymbopogon winterians, Trachyspermum ammi, Zingiber officinalis, Citrus limon, Cinnamomon zeylanicum, Salvia sclarea, Citrus aurantifolia, Melaleuca alternifolia, Citrus aurantium, Citrus bergamia, Pogostemon pathchouli, Cedrus atlantica, Jasminum officinale, Juniperus communis, Abelmoschus moschatus, Cyperus scariosus, Palargonium graveolens, Boswellia carterii, Rosa damascene, Veteveria zizanoides and Commiphora myrrha were evaluated. The essential oils of Cymbopogon winterians, Mentha piperita, Cinnamomum zeylanicum, Melaleuca alternifolia and Eucalyptus globulus were proved to be most effective against the fungus Trichosporon ovoides.

Synthesis, Characterization and Microbial Activity of Chiral Mixed Ligand Transition Metal Complexes

Chiral mixed ligand (CML) metal complexes are synthesized by using isonitrosopropiophenone (HINPP) as a primary ligand and saccharides such as (+)-glucose and/or (-)-fructose as a chiral secondary ligand. The metal complexes have been characterized by elemental analysis and various physico-chemical techniques such as molar conductance, magnetic susceptibility, electronic absorption, infrared spectral studies and thermal analysis. Room temperature magnetic susceptibility measurements of these complexes are indicative of a tetrahedral and/or octahedral geometry. The molar conductance studies of the complexes indicate their non-electrolytic nature. Electronic absorption/reflectance spectra of the complexes show intra- ligand, charge transfer, and the d-d transitions, consistent with their proposed geometry. Thermal studies show the presence of lattice water in the complexes. The specific rotation of the complexes is due to the corresponding chiral saccharide moiety. The Paper Disc Diffusion method has been used to study the antibacterial activity of the compounds against some of the pathogenic bacteria such as C. diphtheriae, E. coli, S. typhi, S. dysenteriae, S. aureus and V. cholerae. The antifungal activity of the complexes against some of the pathogenic fungi such as Candida albicans and Aspergillus niger has been studied by tube dilution method. The results have been compared against those of controls, which were screened simultaneously. The complexes have been screened for acute oral toxicity in albino rats.

Comparative Analysis by GC-MS and in vitro Antimicrobial Activity of the Essential Oils of Noxious Weed (Lantana camara L.) from Western Ghats Region of North West Karnataka, India

The essential oils obtained by hydro distillation from the leaves and flowers of Lantana camara L. (Verbenaceae) and were analyzed by GC-FID and GC-MS. A total of fifty-nine compounds have been identified comprising 91.8% (leaves) and 95.7% (flowers) of the volatile constituents. The leaves essential oil contained α-zingiberene (13.4%), γ-curcumene (11.7%), (β-caryophyllene (10.6%), ar-curcumene (5.6%), 1,10-di-epi-cubenol (5.1%), (β-curcumene (4.9%) and caryophyllene oxide (4.8%) as the main components whereas the flowers essential oil was dominated by (β-caryophyllene (21.7%), ar-curcumene (20.6%), γ-gurjunene (19.6%), γ-curcumene (10.2%) and (β-curcumene (6.5%) as the major constituents. Both the oils were screened for their antimicrobial activity by tube dilution method against six Gram-positive, eight Gram-negative bacteria and three fungi. The organism Micrococcus flavus (Gram-positive bacteria) was found more susceptible to the leaves and flowers oils with MIC value of 0.06±0.01 mg/mL and 0.26±0.03 mg/mL, respectively. The leaves and flowers oils were found to be active against Proteus mirabilis at a concentration of 0.83±0.13 mg/mL and 0.47±0.07 mg/mL, respectively. The microorganism Aspergillus niger was found susceptible to the flowers oil with MIC of 0.22±0.04 mg/mL, while Penicillium chrysogenum was susceptible at a concentration of 0.18±0.04 mg/mL.

Evaluation of chemical composition and efficacy of Chinese propolis extract on Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans: An in vitro study

Background:Propolis as a natural remedy has maintained its popularity over long periods of time. The aim of this study was to determine the chemical composition in terms of total phenolic compounds and flavonoids present in Chinese propolis and to carry out an in vitro evaluation of its antimicrobial activity and the minimal inhibitory concentrations for Porphyromonas gingivalis (Pg) and Aggregatibacter actinomycetemcomitans (Aa).Materials and Methods:From the ethanolic extract of propolis (EEP), total phenol content was determined by the Folin–Ciocalteau method, flavones and flavonols by the modified aluminum chloride colorimetric method, and flavanones by the 2.4-dinitrophenylhydrazine (2,4-DNP) method. Agar well diffusion assay was used to evaluate the antimicrobial potential of propolis against Pg and Aa. The minimum inhibitory concentration of propolis against the two bacteria was determined using serial tube dilution technique.Results:The total concentration of phenol in the EEP was 19.44%, flavones and flavonols 2.616%, and flavanones 16.176%. The inhibitory zone depicting antimicrobial activity ranged from 18 to 25 mm for Pg and from 12 to 14 mm for Aa. The concentration range of Chinese propolis that is sensitive to inhibit the growth of Pg was 0.1–0.0125 μg/ml and for Aa it was 0.1–0.025 μg/ml.Conclusion:These data suggest that Chinese propolis has potent antimicrobial activity against the two periodontopathogens, suggesting its possible use as a natural alternative to the widely used synthetic antibiotics for periodontal therapy.

Potent Antifungal and Antistaphylococcal 2-Anilinobenzimidazoles

A series of 21 anilinobenzimidazoles with a 2,4-difluorophenyl group were synthesized and their minimum inhibitory concentrations (MIC) determined by the tube dilution method. Most of the compounds exhibited excellent MIC values against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Among them, compound 27 having dibromo substitution at the 4- and 6-position of the benzimidazole ring showed the best antifungal activity against Candida krusei with a MIC value of 3.12 microg/mL that surpassed that of the reference drug fluconazole.

In vitro antimicrobial status of methanolic extract of Citrus sinensis Linn. fruit peel

Aim : The present investigation evaluated the antimicrobial potential of methanolic extract of Citrus sinensis Linn. (Rutaceae) fruit peel. There is a basis for the traditional use of this plant for local health remedies. Materials and Methods: The antimicrobial activity of methanolic extract of C. sinensis fruit peel was tested against three bacterial and two fungal strains. Turbidimetric or tube dilution method and paper disc diffusion method were followed. Results are expressed as mean ± standard deviation. Results: The C. sinensis fruit peel methanolic extract exhibited antibacterial activity against Escherichia coli with minimum inhibitory concentration of 0.78 μg/ ml and minimum bactericidal concentration of 6.25 μg/ml, and appreciable antifungal activity with minimum inhibitory concentration of 12.5 μg/ml. The phytochemistry of C. sinensis fruit peel methanolic extract revealed the presence of carbohydrates (reducing sugars, hexose sugars, non-reducing polysaccharides, gums, and mucilages), flavonoid glycosides, coumarin glycosides, volatile oils, organic acids, fats and fixed oils. Conclusion: Most of the organic chemical constituents reported are aromatic phenolic compounds, which are known for their wide spectra of antimicrobial activity. Therefore, the bacteriostatic and fungistatic action of the tested extract may be attributed to the presence of polyphenolic compounds. In short, C. sinensis fruit peel methanolic extract is a potential source of natural antimicrobials.

In vitro Antimicrobial Activity of the Essential Oil of the Endemic Plant Senecio belgaumensis

The aim of present work was to investigate antimicrobial activity of essential oil of the endemic species of Senecio belgaumensis (Wight) Cl., against human pathogenic Gram-positive, Gram-negative bacteria and fungi. The antimicrobial activity of essential oil was determined by tube dilution method. Further, bacteriostatic and bactericidal concentrations were determined for each strain that evidence quantitative analysis. The oil was effective against the microorganism Streptococcus faecalis (Gram-positive bacteria) (MIC 0.015 ± 0.002; MBC 0.025 ± 0.004) followed by Aspergillus fumigatus (MIC 0.045 ± 0.006 mg/mL; MBC 0.052 ± 0.008 mg/mL) and Aspergillus niger (MIC 0.104 ± 0.016 mg/mL; MBC 0.130 ± 0.016 mg/mL) (fungi). The oil showed bacteriostatic and bactericidal activities against all tested strains except Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa (Gram-negative bacteria). The essential oil exhibited satisfactory antimicrobial activity, which could be used for the development of novel antimicrobial agents.

Controlled-release and antibacterial studies of doxycycline-loaded poly(ε-caprolactone) microspheres

The objective of the present study is to achieve doxycycline’s maximum therapeutic efficacy. Doxycycline-loaded poly(ε-caprolactone) microspheres were prepared by water-in-oil-in-water (w/o/w) double emulsion solvent evaporation technique with different formulation variables such as concentrations of drug and polymer. The effects of these variables on surface morphology, particle size distribution, encapsulation efficiency, and in vitro release behavior were examined. To observe the nature of microspheres, X-ray diffraction studies were carried out. The release data obtained were determined using various kinetic models and Korsmeyer–Peppas model showed an acceptable regression value for all compositions. Antibacterial efficiency of doxycycline-loaded poly(ε-caprolactone) microspheres were assessed by determining Minimum Inhibition Concentration (MIC) by standard tube dilution method against four standard pathogenic strains. The in vitro drug release studies were carried out in phosphate buffer solution (pH 7.2). The results showed marked retardation of doxycycline release and higher percentage of polymer gave longer drug release profile. This may definitely provide a useful controlled-release drug therapy and also prove to be effective over a long period of time (76h).

Synthesis of 1,3,5-trisubstituted pyrazoline nucleus containing compounds and screening for antimicrobial activity

In this study, a novel series of heterocyclic compounds containing pyrazoline nucleus has been synthesized. The compounds were synthesized in two steps. Chalcone was synthesized in the first step by Claisen-Schmidt reaction, using 1-acetylnaphthalene and p-nitro benzaldehyde as reactants. In the second step, the chalcone was cyclized in an acidic medium with some hydrazine derivatives to form pyrazolines. All the compounds were characterized by physical, chromatographic, spectroscopic, and elemental analysis and evaluated in vitro for antimicrobial activity against nine microorganisms by cup-plate method. The minimum inhibitory concentration of all the compounds was determined by tube dilution method. All the compounds exhibited higher antibacterial activity as compared to the antifungal activity. Compound 5g (3-Naphthalen-1-yl-1-(2-nitro-phenyl)-5-(4-nitro-phenyl)-4,5-dihydro-1H-pyrazole) exhibited maximum antibacterial and antifungal activity and may be designated as the most potent member of the series, with 2-nitrophenyl group at N-1 position of the 2-pyrazoline ring.

Regeneration of Centella asiatica plants from non-embryogenic cell lines and evaluation of antibacterial and antifungal properties of regenerated calli and plants

BackgroundThe threatened plant Centella asiatica L. is traditionallyused for a number of remedies. In vitro plant propagation and enhanced metabolite production of active metabolites through biotechnological approaches has gained attention in recent years.ResultsPresent study reveals that 6-benzyladenine (BA) either alone or in combination with 1-naphthalene acetic acid (NAA) supplemented in Murashige and Skoog (MS) medium at different concentrations produced good quality callus from leaf explants of C. asiatica. The calli produced on different plant growth regulators at different concentrations were mostly embryogenic and green. Highest shoot regeneration efficiency; 10 shoots per callus explant, from non-embryogenic callus was observed on 4.42 μM BA with 5.37 μM NAA. Best rooting response was observed at 5.37 and 10.74 μM NAA with 20 average number of roots per explant. Calli and regenerated plants extracts inhibited bacterial growth with mean zone of inhibition 9-13 mm diameter when tested against six bacterial strains using agar well diffusion method. Agar tube dilution method for antifungal assay showed 3.2-76% growth inhibition of Mucor species, Aspergillus fumigatus and Fusarium moliniformes.ConclusionsThe present investigation reveals that non-embryogenic callus can be turned into embryos and plantlets if cultured on appropriate medium. Furthermore, callus from leaf explant of C. asiatica can be a good source for production of antimicrobial compounds through bioreactor.

A novel particle sampling system for physico-chemical and toxicological characterization of emissions

Several studies have shown that combustion-derived fine particles cause adverse health effects. Previous toxicological studies on combustion-derived fine particles have rarely involved multiple endpoints and a detailed characterization of chemical composition. In this study, we developed a novel particle sampling system for toxicological and chemical characterization (PSTC), consisting of the Dekati Gravimetric Impactor (DGI) and a porous tube diluter. Physico-chemical and toxicological properties of the particles emitted from various combustion sources were evaluated in two measurement campaigns. First, the DGI was compared with the High-Volume Cascade Impactor (HVCI) and to the Dekati Low-Pressure Impactor (DLPI), using the same dilution system and the same sampling conditions. Only small differences were observed in the mass size distributions, total particulate matter (PM), and particulate matter with diameter smaller than 1 um (PM(1)) concentrations and geometric mass mean diameters (GMMD) between these three impactors. Second, the PSTC was compared with the HVCI sampling system, which has been optimal for collection of particulate samples for toxicological and chemical analyses. Differences were observed in the mass size distributions, total PM and PM(1) emissions, and GMMDs, probably due to the different sampling and dilution methods as well as different sampling substrates which affected the behavior of semi-volatile and volatile organic compounds. However, no significant differences were detected in the in vitro measurements of cytotoxicity between the samples collected with the PSTC and the HVCI systems. In measurements of genotoxicity, significant differences between the two sampling systems were seen only with the particles emitted from the sauna stove. In conclusion, due to compact size, PSTC is an applicable method for use in particle sampling as part of the toxicological and chemical characterization of particulate emissions from different combustion sources. It offers some advantages compared to the previously used high-volume sampling methods including compactness for field measurements, simple preparation of sample substrates and high extraction efficiency.

Synthesis, Characterization, and Antibacterial Studies of Mixed Ligand Dioxouranium Complexes with 8-Hydroxyquinoline and Some Amino Acids

Mixed ligand complexes of dioxouranium (VI) of the type [UO2(Q)(L)·2H2O] have been synthesized using 8-hydroxyquinoline (HQ) as a primary ligand and amino acids (HL) such as L-threonine, L-tryptophan, and L-isoleucine as secondary ligands. The metal complexes have been characterized by elemental analysis, electrical conductance, magnetic susceptibility measurements, and spectral and thermal studies. The electrical conductance studies of the complexes indicate their nonelectrolytic nature. Magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes show intraligand and charge transfer transitions, respectively. Bonding of the metal ion through N- and O-donor atoms of the ligands is revealed by IR studies, and the chemical environment of the protons is confirmed by NMR studies. The thermal analysis data of the complexes indicate the presence of coordinated water molecules. The agar cup and tube dilution methods have been used to study the antibacterial activity of the complexes against the pathogenic bacteria S. aureus, C. diphtheriae, S. typhi, and E. coli.

Traditional antibacterial activity of freshwater microalga Spirulina platensis to aquatic pathogens

The crude ethanol, methanol and aqueous extracts of Spirulina (Spirulina platensis) have been investigated for antibacterial activity using disc diffusion assays against various strains of fish and shellfish pathogens e.g. Pseudomonas putida (ATCC 49128; PP1, PP2), Pseudomonas aeruginosa (ATCC 35032; PA1, PA2), Pseudomonas fluorescens (PF1, PF2), Aeromonas hydrophila (ATCC 49140; AH1, AH2, AH3, AH4), Vibrio alginolyticus (VA), Vibrio anguillarum (VAN), Vibrio fluvialis (VF), Vibrio parahaemolyticus (VP), Vibrio harveyi (VH), Vibrio fisheri (VFS), Edwardsiella tarda and animal isolates of Escherichia coli (O115, O1, O156, O164, O111 and O109). The minimum inhibitory concentrations (MIC) of crude extracts were determined using the tube dilution method. Ethanolic extract showed comparatively higher antibacterial activity (15.66 mm) than that of methanolic and aqueous extract of S. platensis along with their respective MIC values, ranging from 100 to 150 μg mL−1. The aqueous extract had no effective antibacterial activity against the test microorganism. The study suggested that S. platensis may have potential use in aqua feed as an antimicrobial agent of pharmaceutical interest.

A Nonstaining and Tasteless Hydrophobic Salt of Chlorhexidine

Chlorhexidine (CHX) remains one of the most effective and widely used antiplaque agents around the world, although its side effects still limit a long-term usage as the patient compliance for oral treatment with CHX. We hypothesize that a less water-soluble tetracation salt of CHX might be able to interact weakly with tooth enamel and oral taste cells, reducing those undesirable side effects of CHX. The chlorhexidine tetrapalmitate (CHXTP) was obtained and the antimicrobial activity was evaluated by hole-plate diffusion method and twofold tube dilution method; for measurement of its propensity to stain, we used the in vitro method of polymethylmethacrylate blocks in an infusion with black tea solution; the rate of its removal from oral cavity was studied by high-performance liquid chromatography measurement of CHX extracted from human saliva samples; and its effect on the human taste perception was evaluated by taste confusion matrix method. The results showed that CHXTP salt is very active against Streptococcus mutans, with no interference on taste perception and a low tendency to stain; however, chlorhexidine digluconate shows a better retention in saliva. The use of polyvinylpyrrolidone turned possible a nonstaining and tasteless CHXTP formulation to linger in mouth.