Mecanismos de expressão de resistência aos antibióticos e saúde pública / Mechanisms of expression of resistance to antibiotics and public health / Mecanismos de expresión de la resistencia a los antibióticos y salud pública

Com o avanço da medicina e o aumento do uso de antimicrobianos, a resistência microbiana vem se tornando um problema sério na saúde pública. Para que uma bactéria se torne resistente, são necessários vários fatores, entre eles, o uso indiscriminado e prolongado de antimicrobianos e as resistências intrínsecas e adquiridas. Nesse contexto, o objetivo do trabalho foi explorar os mecanismos de ação dos antimicrobianos, de resistência e a sua importância na saúde pública. Foram utilizadas para a presente pesquisa, as bases de dados Pubmed, Google acadêmico e Scielo. Segundo a Organização Mundial da Saúde define-se resistência ao antibiótico quando o mesmo não produz mais efeito. A inserção cada vez mais frequente de antimicrobianos favorece a resistência, onde provocam uma pressão seletiva sobre os microrganismos, tornando-os resistentes a diversas drogas. O uso indiscriminado de antimicrobianos é o principal fator de resistência microbiana, assim como o uso de antimicrobianos sem exame de cultura e teste de sensibilidade. Neste sentido, conclui-se que é de suma importância a atualização de protocolos que contenham os mecanismos de resistência bacteriana a fim de minimizar o uso indiscriminado de antimicrobianos, assim como capacitar os profissionais da saúde para este problema na saúde pública.

With the advance of medicine and the increase in the use of antimicrobials, microbial resistance has become a serious problem in public health. For a bacterium to become resistant, several factors are necessary, among them, the indiscriminate and prolonged use of antimicrobials and the intrinsic and acquired resistance. In this context, the objective of the work was to explore the mechanisms of action of antimicrobials, resistance and their importance in public health. Pubmed, Google academic and Scielo databases were used for this research. According to the World Health Organization, resistance to antibiotics is defined when it no longer has an effect. The increasingly frequent insertion of antimicrobials favors resistance, where they put selective pressure on microorganisms, making them resistant to various drugs. The indiscriminate use of antimicrobials is the main factor of microbial resistance, as well as the use of antimicrobials without culture examination and sensitivity test. In this sense, it is concluded that it is extremely important to update protocols that contain the mechanisms of bacterial resistance in order to minimize the indiscriminate use of antimicrobials, as well as to train health professionals for this problem in public health.

Con los avances de la medicina y el mayor uso de antimicrobianos, la resistencia microbiana se ha convertido en un grave problema de salud pública. Para que una bacteria se vuelva resistente son necesarios varios factores, entre ellos, el uso indiscriminado y prolongado de antimicrobianos y la resistencia intrínseca y adquirida. En este contexto, el objetivo de este trabajo fue explorar los mecanismos de acción de los antimicrobianos, la resistencia y su importancia en la salud pública. Para esta investigación se utilizaron las bases de datos Pubmed, Google Scholar y Scielo. Según la Organización Mundial de la Salud, la resistencia a un antibiótico se define cuando deja de producir efecto. El uso cada vez más frecuente de antimicrobianos favorece la resistencia, ya que provocan una presión selectiva sobre los microorganismos, haciéndolos resistentes a varios fármacos. El uso indiscriminado de antimicrobianos es el principal factor de resistencia microbiana, así como el uso de antimicrobianos sin pruebas de cultivo y sensibilidad. En este sentido, se concluye que es de suma importancia actualizar los protocolos que contienen los mecanismos de resistencia bacteriana para minimizar el uso indiscriminado de antimicrobianos, así como capacitar a los profesionales de la salud para este problema en la salud pública.

A new coumarin derivative, 4-acetatecoumarin, with antifungal activity and association study against Aspergillus spp

Abstract Fungal infections have become a concern for health professionals, and the emergence of resistant strains has been reported for all known classes of antifungal drugs. Among the fungi causing disease, we highlight those that belong to the genus Aspergillus. For these reasons, the search for new antifungals is important. This study examines the effects of a coumarin derivative, 4-acetatecoumarin (Cou-UMB16) both alone and together with antifungal drugs, and its mode of action against Aspergillus spp. Cou-UMB16 was tested to evaluate its effects on mycelia growth, and germination of Aspergillus spp. fungal conidia. We investigated its possible action on cell walls, on the cell membrane, and also the capacity of this coumarin derivative to enhance the activity of antifungal drugs. Our results suggest that Cou-UMB16 inhibits Aspergillus spp. virulence factors (mycelia growth and germination of conidia) and affects the structure of the fungal cell wall. When applying Cou-UMB16 in combination with azoles, both synergistic and additive effects were observed. This study concludes that Cou-UMB16 inhibits mycelial growth and spore germination, and that the activity is due to its action on the fungal cell wall, and that Cou-UMB16 could act as an antifungal modifier.

Therapeutic targets in Paracoccidioides brasiliensis: post-transcriptome perspectives

The rise in antifungal resistance, observed as a result of the increasing numbers of immunocompromised patients, has made the discovery of new targets for drug therapy imperative. The description of the Paracoccidioides brasiliensis transcriptome has allowed us to find alternatives to refine current therapy against paracoccidioidomycosis. We used comparative analysis of expressed sequence tags to find promising drug targets that have been addressed in other pathogens. We divided the analysis into six different categories, based on the involvement of the targeted mechanisms in the cell: i) cell wall construction, ii) plasma membrane composition, iii) cellular machinery, iv) cellular metabolism, v) signaling pathways, and vi) other essential processes. Through this approach, it has been possible to infer strategies to develop alternative drugs against this pathogen.

Effect of sugars on the association between cowpea vicilin (7S storage proteins) and fungal cells

Vicilins (7S storage proteins) found in various legume seeds have been previously shown to interfere with the germination of spores or conidia of phytopathogenic fungi and inhibit yeast growth and glucose stimulated acidification of the medium by yeast cells. In the present work vicilins from cowpea (Vigna unguiculata) seeds were added to the growth medium of Saccharomyces cerevisiae cells and Fusarium oxysporum conidia. Helix pomatia lectin, wheat germ agglutinin and Ulex europaeus lectin were used to identify differences in the binding of the vicilins to the surface of cells of S. cerevisiae and F. oxysporum treated with this protein. After the growth period, the material in suspension (yeast cells) was centrifuged and the final pellet was also treated with different sugar (glucose, sucrose, glucosamine, N-acetyl-glucosamine) concentrations and 0.1 M HCl for extraction of vicilins associated to chitinous structures present in yeast cells. Our results showed that vicilin sub-units were present in the different sugar extracts of yeast cells pretreated with the vicilins and these proteins were eluted by 0.5 M solutions of sugars in the following order of efficiency of elution: N-acetyl-glucosamine, sucrose/glucose and glucosamine.

Biochemical effects of sparfloxacin on cell envelope of mycobacteria.

Sparfloxacin, a difluorinated quinolone is a potent anti-mycobacterial agent used in the treatment of mycobacterial infections. We have investigated whether sparfloxacin had other, more subtle effects on mycobacteria besides its interaction with DNA gyrase that could contribute to its therapeutic efficacy. Mycobacterium smegmatis cells grown in media with sub-inhibitory concentration of sparfloxacin were observed to have significant reduction in the biosynthesis of vital macromolecules, as shown by the incorporation of various radiolabelled precursors. The analysis of subcellular distribution of phospholipids of sparfloxacin-treated cells demonstrated an increase in the cell membrane and reduction in the cell wall, suggesting changes in the cell envelope architecture by sparfloxacin. Significant changes were also observed in other chemical constituents of the cell wall, especially in the arabinose and glucosamine contents. Mycolic acids, the major component of mycobacterial cell wall were reduced in the presence of MIC50 of sparfloxacin. There was a decrease in the limiting fluorescence intensity (Fmax) of 1-anilinonaphthalene 8-sulfonate (ANS) indicating alterations in the organization and conformation of mycobacterial cell surface. These results suggest that the mechanism of action of anti-mycobacterial action of sparfloxacin involves mycobacterial cell envelope.

Congo red effect on cyst viability and cell wall structure of encysting entamoeba invadens

Background. The cell wall of Entamoeba invadens cysts is composed of chitin microfibrils as the main structural component. It has been demonstrated in yeast that the chitin cell wall assembly is altered by dyes such as Congo red (CR) and Calcofluor. Methods. The purpose of this work was to study the cell wall assambly under the effect of CR dye on encysting E. invadens by means of light and electron microscopy, after the ammebas were subjected to the effect of 100-2,000 µg CR/mL. Experiments were performed either in BI-S-33 or in mLG media. Results. Trophozoit growth was not inhibited by 100-1,000 µg/mL CR after 8 days of incubation in BI-S-33 medium. However, low levels of growth were observed with 2,000 µg/mL of dye. No significant differences in morphologically viable (hyaline) cyst production occurred after 24-48 hm when 100 µg CR/mL was used, while the highest concentration of CR (2,000 µg/mL) resulted in a significant decrease of hyaline cyst yield; dead cysts prevailed in cultures, particularly at 72 h of CR treatment. Differentiation of amebas incubated in the presence of 500-2,000 µg/mL CR produced abnormal chitin deposits, rendering irregulary thick or double cell walls, as shown by transmission and scanning electron microscopy. Cyst cultures obtained under 100 µg/mL CR produced as many trophozoites as did the control when they were incubated in BI-S-33, but only low numbers of trophozoites were found in culture cysts obtained under higher CR doses. Conclusion. Our results suggest that CR affects E. invadens encystment, alters the cell wall formation, and also affects the cyst viability

Antibiotics and garlic clove extract--inhibitory agents of cell wall degrading enzymes.

Four antibiotics were tested against Erwinia causing soft rot of onion (Allium cepa var. aggregatum) of which streptomycin sulphate 90% and tetracycline hydrochloride 10% (streptocycline) recorded the maximum inhibition zone of 27.66 mm. In the enzyme studies the maximum inhibition of pectinlyase (PL), polygalacturonase (PG) and protopectinase production was recorded by the same antibiotic. The antibiotics have a significant influence on the production and activity of cell wall degrading enzymes produced by the plant pathogenic microorganisms. Garlic clove extract was equally effective in inhibiting the growth and enzyme production.

Cell wall deficiency in slime strains of Neurospora crassa: osmotic inhibition of cell wall synthesis and Beta-D-glucan synthase activity

1. The RCP-3 S/H mutant of Neurospora crassa was obtained by vegetative selection in medium of high osmolarity of a mycelial form an fz, sg, os-1 ("smile"-like) segregant. The mutant exhibits spheroplast-hyphal dimorphism conditioned by the osmolarity of the culture medium (pietro et al. (1990). Journal of General Microbiology, 136: 121-129). The carbohydrate composition of the cell wall of the mutant was different from that of the wild type in the absence of an alkalisoluble galactosaminoglycan polymer. Furthermore the mutant cell wall had a somewhat lower content of ß-glucan relative to that of chitin. 2. Increasing concentrations of sorbitol in the culture medium of the mutant inhibited by 10-fold the formation of cell wall relative to toal biomass. The cell wall of the mutant cultured in the presence of sorbitol lacked mannose-and galactose-containing polymers, and also showed progressively lower amounts of ß-glucan relative to chitin. 3. The activity of membrane-bound (1-3)-ß-D-glucan synthase from the mutant grown in the absence of sorbitol shared several properties with the wil type enzyme (i.e., Km app, Vmax, stability at 30ºC, activation by GTPyS, and dissociability by treatment with NaCl and Tergitol NP-40 into a membrane-bound catalytic center and GTP-binding activating protein). On the other hand, the enzyme from the mutant but not that from the wild type was inactivated by about 15 per cent by treatment with NaCl and detergent. 4. At high concentrations of sorbitol (1.0M) the RCP-3 S/H mutant exclusively produced spheroplasts devoid of (1-3)-ß-D-glucan synthase activity. The defect was at the level of the membrane-bound catalytic center. The activity of the GTP-binding activating factor was apparently normal in these cells. 5. These results suggest that the definitive loss of cell wall in the N. crassa "slime" RCP-3 S/H mutant was due to a defect in (1-3)-ß-D-glucan synthase activity which wass exaggerated in the presence of high osmolyte concentrations

Propiedades de superficie y adherencia de cepas de Acinetobacter baumannii / Surface characteristics and strains adherence of the Acetinetobacter baumannii

En este trabajo se estudió la capacidad que presentaban 14 cepas de Acinetobacter baumannii (A.b.) para adherirse a células epiteliales bucales (CEB), sustratos no biológicos y su correlación con el mecanismo de interacción hidrofóbica. Se estimó la adherencia de A.b. a CEB, mediante recuento microscópico en 40 CEB, y la hidrofobicidad de la superficie celular mediante la acción de agentes fisicoquímicos y la capacidad de unión a compuestos hidrofóbicos. El 92% de las cepas se unió a CEB (p<0,001). El 35% lo hizo marcadamente frente al cloruro de polivinilo (PVC) y xileno; un mayor porcentaje se unió al poliestireno (PE), pero con intensidad variable entre las distintas cepas. Una sola cepa autoagregó formando, en cultivos estáticos, película cohesiva en la interfase aire-líquido; esta misma cepa presentó el mayor valor de agregación después de calentar 1h a temperatura de ebullición. Los fenotipos hidrofóbicos agregaban a menor concentración de sulfato de amonio, excepto una cepa mucosa de A.b.. Hubo correlación en el comportamiento hidrofóbico e hidrofílico entre las distintas cepas. Solo una cepa se comportó como no adherente frente a los sustratos biológicos y no biológicos ensayados. Las diferentes características de superficie de las cepas estudiadas podría ser explicado por la heterogeneidad de la superficie celular, según se observa en los perfiles de membrana externa. Los datos indicarían que si bien la hidrofobicidad sola no podría ser considerada un factor relevante en la adherencia a CEB, es posible que tenga un efecto importante cuando se considera junto a otros factores, tales como carga de superficie, concentración iónica del medio y tensión interfasial

Avaliaçäo das atividades antiexsudativa e antiproliferativa dos antiinflamatórios näo esteróides Naproxen, Ibuprofen, Sulindac e Glucametacina em modelos inflamatórios produzidos pela inoculaçäo subcutânea de fragmentos de parede celular de microorganismos da placa dental / Evaluation of antiexsudative and antiproliferative activities of non-steroidal antiinflammatory Naproxen, Ibuprofen, Sulindac and Glucamethacin in inflammatory models produced by subcutaneous inoculation of cell wall fragments of dental plaque microo

A inflamaçäo aguda constitui-se em uma resposta tecidual inicial a todas as formas de agressäo, qualquer que seja o agente etiológico, sendo as suas principais características a exsudaçäo de líquidos e de proteínas plasmáticas do sangue para o interstício e a transmigraçäo de células, principalmente de leucócitos polimorfonucleares neutrófilos. A cura do processo inflamatório ocorre após a eliminaçäo do agente etiológico através do processo de reparo. Entretanto, quando certos agentes nocivos näo podem ser destruídos ou eliminados, a inflamaçäo persiste e tenta isolá-los do organismo formando o granuloma. Existem muitas condiçöes inflamatórias de origem ainda desconhecida, como a artrite reumatóide, onde se manifestam tanto os fenômenos exsudativos como os proliferativos da inflamaçäo, que determinam alteraçöes funcionais e deformidades articulares irreversíveis, em geral acompanhadas de notáveis manifestaçöes sistêmicas. Embora as drogas antiinflamatórias sejam utilizadas para modificar a resposta inflamatória nas doenças de etiologia desconhecida, a terapêutica näo é curativa, pois muitas vezes estäo envolvidos mecanismos etiopatogenéticos complexos e ainda obscuros da doença, o que torna a droga inespecífica. O seu efeito acha-se fundamentalmente dirigido ao tratamento sintomático da inflamaçäo, ou seja, diminuindo ou bloqueando os sinais e sintomas locais e sistêmicos dessa inflamaçäo. Os antiinflamatórios näo esteróides säo também analgésicos e antipiréticos e, recentemente, tem-se observado também atividade antimitótica. Entretanto, como a sua atividade antimitótica näo tem sido estudada de modo sistêmico, propusemo-nos a determinar in vivo, além da atividade antiinflamatória, também a sua atividade antimitótica em quatro drogas antiinflamatórias näo esteróides, bem como estabelecer a correlaçäo existente entre os dois efeitos (antiinflamatório e antimitótico). As drogas testadas foram: naproxen, ibuprofen, sulindac e glucametacina. Neste estudo foram utilizados 321 ratos adultos, da linhagem Wistar (Rattus novergicus, var. albino), com peso médio de 250 gramas, cujos animais experimentais foram medicados com doses diárias de 33,34mg/kg de naproxen, 80mg/kg de ibuprofen, 13,34mg/kg de sulindac e 14mg de glucametacina. Os animais controles receberam apenas água destilada em substituiçäo às drogas. A administraçäo das drogas ou da água destilada foi feita por intubaçäo gástrica...

Mecanismos de hormonas reguladoras de la secrecion de insulina / Mechanisms of regulatory hormones on insuline secretion

Revision de los mecanismos secretores de insulina y las funciones de esta hormona en el metabolismo celular.

Ultraestructura de quistes de Entamoeba invadens obtenidos bajo el efecto de emetina, tinidazol y rifampicina / Ultraestructure of entamoeba invadens cysts obtained under the effect of emetine, tinidazole and rifampin

Se determinaron las concentraciones inhibitorias mínimas (CIM) de emetina, tinidazol y rifampicina para trofozoítos de E. invadens, así como la ultraestructura de quistes obtenidos después de 22 y 45 horas, en presencia de la CIM de los fármacos. Bajo el efecto de tinidazol o de rifampicina los quistes obtenidos mostraron numerosas vacuolas que contenían elementos membranosos y vesículas llenas de material amorfo electrodenso; algunas de éstas se observaron en las proximidades de la membrana plasmática. En los quistes obtenidos en presencia de emetina, el citoplasma presentó numerosas vesículas y cisternas aplanadas particularmente después de 22 horas de incubación en médio de enquistamiento, las que disminuyeron después de 45 horas de diferenciación; se observaron además vasículas con material electrodenso próximas a la membrana plasmática. Las paredes celulares de los quistes obtenido bajo el efecto de los fármacos mencionados fueron irregulares tanto en el arreglo fibrilar como en el espesor; adicionalmente, bajo los efectos de tinidazol y emetina las paredes de los quistes se perdieron parcial o totalmente, observándose acúmlos de éstas entre los quistes. Los resultados sugieren que la CIM de los fármacos empleados provocaron un retardo en el proceso de difereciación de E. invadens y, posiblemente, interfieran con el ensamble de la pared celular y con la adherencia de ésta a la membrana plasmática durante el enquistamiento