Antimicrobial activity of different disinfectants against cariogenic microorganisms

Abstract The aim of this study was to assess the in vitro antimicrobial effects of chlorhexidine digluconate (CHX), polyhexamethylene biguanide (PHBM), and octenidine dihydrochloride (OCT) on cariogenic microorganisms by using their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). CHX, PHBM, and OCT were diluted in distilled water to the final test concentrations. Using the in-tube dilution method, Streptococcus mutans, Lactobacillus acidophilus, Lactobacillus rhamnosus, and Actinomyces viscosus were cultivated on blood agar and Mueller-Hinton broth (MHB) at 37°C for 48 h. They were read using a spectrophotometer to detect MIC. To determine MBC, samples in the range of the turbidity threshold after 24 h were transferred onto blood agar and evaluated for growth after 24 h. Different MICs and MBCs were observed in all disinfectants against each microorganism. The lowest MIC and MBC against S. mutans (60 mg/L) were obtained from PHBM. The lowest values against L. rhamnosus (15 mg/L, 30 mg/L), A. viscosus (30 mg/L), and L. acidophilus (15 mg/L, 30 mg/L) were determined by OCT. PHBM and OCT have the potential to be replaced with CHX because they were effective against cariogenic microorganisms.

Bioactive endophytic fungi isolated from Caesalpinia echinata Lam. (Brazilwood) and identification of beauvericin as a trypanocidal metabolite from Fusarium sp.

Aiming to identify new sources of bioactive secondary metabolites, we isolated 82 endophytic fungi from stems and barks of the native Brazilian tree Caesalpinia echinata Lam. (Fabaceae). We tested their ethyl acetate extracts in several in vitro assays. The organic extracts from three isolates showed antibacterial activity against Staphylococcus aureus and Escherichia coli [minimal inhibitory concentration (MIC) 32-64 μg/mL]. One isolate inhibited the growth of Salmonella typhimurium (MIC 64 μg/mL) and two isolates inhibited the growth of Klebsiella oxytoca (MIC 64 μg/mL), Candida albicans and Candida tropicalis (MIC 64-128 μg/mL). Fourteen extracts at a concentration of 20 μg/mL showed antitumour activities against human breast cancer and human renal cancer cells, while two isolates showed anti-tumour activities against human melanoma cancer cells. Six extracts were able to reduce the proliferation of human peripheral blood mononuclear cells, indicating some degree of selective toxicity. Four isolates were able to inhibit Leishmania (Leishmania) amazonensis and one isolate inhibited Trypanosoma cruzi by at least 40% at 20 μg/mL. The trypanocidal extract obtained from Fusarium sp. [KF611679] culture was subjected to bioguided fractionation, which revealed beauvericin as the compound responsible for the observed toxicity of Fusarium sp. to T. cruzi. This depsipeptide showed a half maximal inhibitory concentration of 1.9 μg/mL (2.43 μM) in a T. cruzi cellular culture assay.

Efeitos do aditivo do leite materno com ferro sobre as propriedades bacteriostáticas do leite materno / Effects of human milk fortifier with iron on the bacteriostatic properties of breast milk

OBJETIVO: Comparar o crescimento bacteriano em colostro puro e colostro com aditivo do leite materno contendo ferro. MÉTODOS: Foram comparadas 78 amostras de colostro puro ou colostro com adição de aditivo do leite materno contendo ferro para avaliar o crescimento de Escherichia coli, Staphylococcus aureus e Pseudomonas aeruginosa. Para a análise qualitativa, discos de papel-filtro foram imersos em amostras de cada grupo e incubados por 48 horas com 10¹ Unidades Formadoras de Colônias/mL de cada cepa. Para a avaliação quantitativa, 1 mL de cada cepa contendo 10(7) Unidades Formadoras de Colônias/mL foi homogeneizado com 1 mL, tanto de colostro puro quanto de colostro com aditivo do leite materno, espalhado em placa de Petri e incubado a 37ºC. O número de Unidades Formadoras de Colônias foi contado 24 horas depois. RESULTADOS: A análise qualitativa não mostrou nenhuma diferença no crescimento bacteriano. Na avaliação quantitativa, o crescimento de Escherichia coli (EC) no grupo C foi de 29,4±9,7 x 10(6) CFU/mL, enquanto no grupo FM85 foi de 31,2±10,8 x 10(6) CFU/mL. A diferença entre o crescimento médio foi de 1,9±4,9 x 10(6) CFU/mL (p = 0,001). Não houve diferenças no crescimento de Staphylococcus aureus e Pseudomonas aeruginosa. CONCLUSÃO: A adição de ferro a essa concentração reduz a ação bacteriostática do leite materno contra Escherichia coli.

OBJECTIVE: To compare bacterial growth in pure colostrum versus colostrum with human milk fortifier (HMF) containing iron. METHODS: The growth of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa in 78 samples of pure colostrum or colostrum with added iron-containing HMF was compared. For qualitative analysis, filter paper discs were immersed in samples from each group and incubated for 48 hours with 10¹ colony forming units (CFUs)/mL of each strain. For quantitative assessment, 1 mL of each strain containing 10(7) CFUs/mL was homogenized with 1 mL of either colostrum or colostrum with human milk fortifier, seeded into a Petri dish, and incubated at 37ºC. Twenty-four hours later, the number of CFUs was counted. RESULTS: The qualitative analysis showed no difference in bacterial growth. In the quantitative evaluation, E. coli growth in the control group was 29.4±9.7 x 10(6) CFU/ mL, while in the HMF group it was 31.2±10.8 x 10(6) CFU/mL. The difference between the average growth was 1.9±4.9 x 10(6) CFU/mL (p = 0.001). There were no differences in S. aureus and P. aeruginosa growth. CONCLUSION: Addition of iron at this concentration reduces breast milk bacteriostatic action against E. coli.

Evaluation of silicon oil on bacterial growth / Avaliação dos efeitos do óleo de silicone no crescimento bacteriano

PURPOSE: To analyze the antimicrobial properties of silicon oil (Óleo de Silicone®, Ophthalmos, Brazil) on in vitro bacterial growth of different microorganisms related to endophthalmitis. METHODS: The following microorganisms were analyzed: (1) Pseudomonas aeruginosa (ATCC 27583); (2) Escherichia coli (ATCC 25922); (3) Staphylococcus aureus (ATCC 25923); (4) Staphylococcus epidermidis (ATCC 12228); (5) Candida albicans (ATCC 10231); (6) Klebsiella pneumoniae (ATCC 13883); and (7) Streptococcus pneumoniae (ATCC 49619). The plates were incubated at 35 ± 2ºC and its growth examined after 24 hours. An empty disk was placed in the center of each plate as a control. RESULTS: No inhibition halos were verified in any of the plates containing the four different concentrations of the bacterial inocula. CONCLUSIONS: The silicon oil 1000 cps does not have any effect on bacterial growth of any of the studied microrganisms.

OBJETIVO: Analisar as propriedades antimicrobianas do óleo de silicone (Óleo de Silicone®, Ophthalmos, Brazil) no crescimento in vitro de diferentes microrganismos relacionados à endoftalmite. MÉTODOS: Os seguintes microrganismos foram analisados: (1) Pseudomonas aeruginosa (ATCC 27583); (2) Escherichia coli (ATCC 25922); (3) Staphylococcus aureus (ATCC 25923); (4) Staphylococcus epidermidis (ATCC 12228); (5) Candida albicans (ATCC 10231); (6) Klebsiella pneumoniae (ATCC 13883); and (7) Streptococcus pneumoniae (ATCC 49619). As placas foram incubadas à temperatura de 35 ± 2ºC e o seu crescimento examinado após 24 horas. Um disco de papel filtro neutro, sem óleo de silicone, foi posicionado no centro de cada placa como controle. RESULTADOS: Não foram encontrados halos de inibição em nenhuma das placas contendo as diferentes concentrações de inóculo bacteriano estudadas. CONCLUSÕES: O Óleo de Silicone® 1000 cps não apresenta efeito no crescimento bacteriano de nenhum dos microrganismos estudados.

Growth and biosurfactant synthesis by Nigerian hydrocarbon-degrading estuarine bacteria

The ability of microorganisms to degrade petroleum hydrocarbons is important for finding an environmentally-friendly method to restoring contaminated environmental matrices. Screening of hydrocarbon-utilizing and biosurfactant-producing abilities of organisms from an estuarine ecosystem in Nigeria, Africa, resulted in the isolation of five microbial strains identified as Corynebacterium sp. DDv1, Flavobacterium sp. DDv2, Micrococcus roseus DDv3, Pseudomonas aeruginosa DDv4 and Saccharomyces cerevisae DDv5. These isolates grew readily on several hydrocarbons including hexadecane, dodecane, crude oil and petroleum fractions. Axenic cultures of the organisms utilized diesel oil (1.0 % v/v) with generation times that ranged significantly (t-test, P < 0.05) between 3.25 and 3.88 day, with concomitant production of biosurfactants. Kinetics of growth indicates that biosurfactant synthesis occurred predominantly during exponential growth phase, suggesting that the bioactive molecules are primary metabolites. Strains DDv1 and DDv4 were evidently the most metabolically active in terms of substrate utilization and biosurfactant synthesis compared to other strains with respective emulsification index of 63 and 78 %. Preliminary biochemical characterization indicates that the biosurfactants are heteropolymers consisting of lipid, protein and carbohydrate moieties. The hydrocarbon catabolic properties coupled with biosurfactant-producing capabilities is an asset that could be exploited for cleanup of oil-contaminated matrices and also in food and cosmetic industries. Rev. Biol. Trop. 56 (4): 16031611. Epub 2008 December 30.

La capacidad de los microorganismos para degradar hidrocarburos del petróleo es de gran importancia para hallar un método aceptable y ambientalmente amigable para la restauración de terrenos ambientalmente contaminados. Al investigar las capacidades de los organismos de un ecosistema de estuario que utilizan hidrocarburos y producen biosurfactantes, se produjo como resultado el aislamiento de cinco cepas microbianas identificadas como Corynebacterium sp. DDv1, Flavobacterium sp. DDv2, Micrococcus roseus DDv3, Pseudomonas aeruginosa y DDv4 Saccharomyces cerevisiae DDv5. Estas cepas crecieron fácilmente en varios hidrocarburos incluyendo hexadecanos, dodecanos, petróleo crudo y fracciones de petróleo. Los cultivos axénicos de organismos utilizaron diesel (1.0% v/v) con períodos por generación con ámbitos significativos (t-test, P <0.05) de entre 3.25 y 3.88 días, con la consiguiente producción de bio-surfactantes. La cinética del crecimiento indica que la síntesis de bio-surfactante se produjo principalmente durante la fase de crecimiento exponencial, lo que sugiere que las moléculas bioactivas son metabolitos primarios. Las cepas DDv1 y DDv4 fueron evidentemente las más metabólicamente activas en términos de utilización del sustrato y la síntesis de bio-surfactantes en comparación con otras cepas con índices respectivos de emulsificación de 63 y 78%. La caracterización bioquímica preliminar indica que los bio-surfactantes son heteropolímeros constituidos de fracciones de lípidos, proteínas y carbohidratos. Las propiedades catabólicas de los hidrocarburos, junto con las capacidades de producción de bio-surfactantes, es una ventaja que puede ser aprovechada para la limpieza de terrenos contaminados con petróleo y también en la industria alimentaria y cosmética.

Physico-chemical and microbial characteristics of the coral reef environment of the Gulf of Mannar marine biosphere reserve, India.

Investigation on physico-chemical parameters and bacteial characteristics of the coral reef environs of the Gulf of Mannar biosphere reserve was studied. The study found the influence of different physico-chemical parameters on one another and also on the distribution of the total heterotrophic bacteria (THB) in the coral reef areas. Nutrients exhibited considerable seasonal and spatial variations with influence on the bacterial population. Coral reef areas recorded higher bacterial population density both in water (3.5 to 18 x 10(5) CFU ml(-1)) and sediment (1 to 14 x 10(7) CFU g(-1)) samples than the non coral reef areas (3.4 to 10.5 x 10(4) CFU ml(-1) in water and 0.9 to 7 x 10(6) CFU g(-1)). The study also found the dominance of gram negative groups at all the three stations (64.73, 63,5 and 72.59%) with Pseudomonas contributing maximum number of strains in all the samples. In addition Vibrio, Aeromonas, Flavobacterium, Cytophaga, Enterobacter and Alcaligenes were also recorded. The gram positive group was represented by Bacillus, Micrococcus, Arthrobacter and Corynebacterium. The genetic composition of THB isolated from the coral mucus revealed the presence of Vibrio and Micrococcus in all the coral mucus.

Diversidad bacteriana en un biorreactor de lecho fluidificado durante el tratamiento de agua contaminada con nafta / Bacterial diversity in a fluidized bed bioreactor (FBR) treating gasoline-contaminated groundwater

El objetivo principal de esta investigación fue determinar la diversidad bacteriana del proceso de biorremediación de agua contaminada con nafta en un biorreactor de lecho fluidificado en el Recinto Universitario de Mayagüez, de la Universidad de Puerto Rico. El aislamiento y la caracterización de las colonias bacterianas del sistema de biorremediación fueron realizados en medio R2A. Las pruebas morfológicas incluyeron la determinación de la morfología celular y de las colonias, y la reacción frente a la coloración de Gram. Las propiedades fisiológicas se determinaron usando el sistema Biolog® y sobre la base de la habilidad para desarrollar en medio mínimo con nafta como única fuente de carbono. La caracterización molecular se llevó a cabo por BOX-PCR y por análisis de secuencia del ADNr 16S mediante la técnica de ARDRA (amplified ribosomal DNA restriction analysis). De los 162 morfotipos de colonias aislados, 75% fueron bacilos gram-negativos, 19% bacilos gram-positivos, 5% cocos gram-negativos y 1% cocos gram-positivos. Según el análisis ARDRA, estos morfotipos se distribuyeron en 90 grupos genéticos, de los cuales 53% incluyeron cepas con crecimiento en nafta. Las 86 cepas que crecieron en nafta presentaron 52 patrones de amplificación, los que a través de BOX-PCR se agruparon en 50 grupos metabólicamente no relacionados. El alto nivel de diversidad microbiana observado en el reactor permitió la remoción del contaminante y, al parecer, fue importante para la operación estable y eficiente del sistema.

The main objective of this research project was to determine the bacterial diversity during the process of bioremediation of water contaminated with gasoline in a fluidized bed reactor at Mayagüez, PR. Isolation and characterization of bacterial populations from the bioremediation system was performed on R2A medium. Morphological tests included cellular and colonial shape and reaction to Gram coloration. Physiological properties were determined by using carbon utilization profiles (Biolog®) and by the ability of axenic cultures to use gasoline as the sole carbon source. Molecular characterization was performed by BOX-PCR and 16S rDNA sequence analysis (ARDRA). From a total of 162 distinctive isolates, 75% were gram-negative bacilli, 19% gram-positive bacilli, 5% gram-negative cocci and 1% gram-positive cocci. The 162 axenic cultures corresponded to 90 different genetic groups; 53% of which included strains with growth in gasoline as sole carbon source. The 86 strains capable of growing in gasoline corresponded to 52 different amplification patterns in BOX-PCR; which were not metabolically related (Biolog® system). The high degree of microbial diversity in the FBR allowed efficient and stable hydrocarbon removal throughout the operation of the system.

Differential activity of a lectin from Solieria filiformis against human pathogenic bacteria

A lectin isolated from the red alga Solieria filiformis was evaluated for its effect on the growth of 8 gram-negative and 3 gram-positive bacteria cultivated in liquid medium (three independent experiments/bacterium). The lectin (500 æg/mL) stimulated the growth of the gram-positive species Bacillus cereus and inhibited the growth of the gram-negative species Serratia marcescens, Salmonella typhi, Klebsiella pneumoniae, Enterobacter aerogenes, Proteus sp, and Pseudomonas aeruginosa at 1000 æg/mL but the lectin (10-1000 æg/mL) had no effect on the growth of the gram-positive bacteria Staphylococcus aureus and B. subtilis, or on the gram-negative bacteria Escherichia coli and Salmonella typhimurium. The purified lectin significantly reduced the cell density of gram-negative bacteria, although no changes in growth phases (log, exponential and of decline) were observed. It is possible that the interaction of S. filiformis lectin with the cell surface receptors of gram-negative bacteria promotes alterations in the flow of nutrients, which would explain the bacteriostatic effect. Growth stimulation of the gram-positive bacterium B. cereus was more marked in the presence of the lectin at a concentration of 1000 æg/mL. The stimulation of the growth of B. cereus was not observed when the lectin was previously incubated with mannan (125 æg/mL), its hapten. Thus, we suggest the involvement of the binding site of the lectin in this effect. The present study reports the first data on the inhibition and stimulation of pathogenic bacterial cells by marine alga lectins.

Microbial flora variations in the respiratory tract of mice

A stable microbial system in the respiratory tract acts as an important defense mechanism against pathogenic microorganisms. Perturbations in this system may allow pathogens to establish. In an ecological environment such as the respiratory tract, there are many diverse factors that play a role in the establishment of the indigenous flora. In the present work we studied the normal microbial flora of different areas of the respiratory tract of mice and their evolution from the time the mice were born. Our interest was to know which were the dominant groups of microorganisms in each area, which were the first capable of colonizing and which dominated over time to be used as probiotic microorganisms. Our results show that Gram negative facultatively anaerobic bacilli and strict anaerobic microorganisms were the last ones to appear in the bronchia, while aerobic and Gram positive cocci were present in all the areas of the respiratory tract. The number of facultative aerobes and strict anaerobes were similar in the nasal passage, pharynx instilled and trachea, but lower in bronchia. The dominant species were Streptococcus viridans and Staphylococcus saprophyticcus, followed by S. epidermidis, Lactobacilli and S. cohnii I which were present on every studied days but at different proportions. This paper is the first part of a research topic investigating the protective effect of the indigenous flora against pathogens using the mice as an experimental model.

Avaliaçäo da atividade antimicrobiana de metabólitos produzidos pelo fungo Nomuraea rileyi (Farlow) samson / Antimicrobial activity evaluation of metabolits produced by the Nomuraea rileyi (Farlow) samson fungus

Metabólitos do fungo entomopatogênico Nomuraea rileyi produzidos em culturas submersas em caldo Sabouraud sacarose extrato de levedura foram extraídos com diclorometano. O extrato bruto foi fracionado por cromatografia em coluna e em camada espessa de fluxo contínuo utilizando benzeno-clorofórmio-acetato de etila 18:1:1 (v:v:v) como eluentes. Amostras de Saccharomyces cerevisiae e de bactérias (18 cepas hospitalares e 5 estirpes fitopatogênicas) foram testadas frente ao metabólito empregando-se o método de difusäo em ágar pelo sistema de discos (Kirby-Bauer). Aproximadamente (40 por cento) (9/23) das amostras bacterianas ensaiadas tiveram seu crescimento inibido na presença do metabólito produzido pelo fungo Nomuraea rileyi, sugerindo uma possível atividade antibacteriana deste metabólito

Inhibitory effect of natural honey on Helicobacter pylori.

Honey is widely used in folk-medicine throughout the world. However, it has a limited use in modern medicine due to lack of scientific support. Based on some recent reports, an in vitro study was undertaken to evaluate its antibacterial activity on Helicobacter pylori and a few other pathogenic organisms. All isolates of H. pylori were inhibited by 20 per cent of honey. Most of the other bacteria examined (including both Gram-positive and Gram-negative) were also inhibited at concentrations of 20 per cent of honey; and half of them were inhibited by 10 per cent of honey. Furthermore, it was observed that some isolates were resistant to various antimicrobial agents but honey inhibited these organisms and the sensitive ones equally. Our study advocates carrying out clinical investigation of the effect of honey on gastroduodenal disorders colonised by H. pylori.