ABSTRACT
Arranjos supramoleculares combinando o lípide catiônico brometo de dioctadecildimetilamônio (DOD) com polímeros, como carboximetilcelulose (CMC) e cloreto de poli(dialildimetilamônio) (PDDA), foram preparados na forma de nanopartículas (NPs), na ausência ou presença de antimicrobiano tradicional, como a claritromicina (CLA). NPs preparadas por atração eletrostática entre os fragmentos de bicamada (BF) de DOD, CMC e PDDA foram avaliadas, in vitro, quanto à atividade contra isolados clínicos de micro-organismos multirresistentes (MR) a antimicrobianos, como Pseudomonas aeruginosa MR, Klebsiella pneumoniae produtora da enzima carbapenemase do tipo KPC, Staphylococcus aureus resistente à meticilina/oxacilina (MRSA) e Candida albicans resistente ao fluconazol, através do método de plaqueamento e contagem de viáveis. As NPs de DOD BF/CMC/PDDA apresentam alta atividade de amplo espectro contra micro-organismos MR, em que o PDDA é o componente responsável pela excelente atividade biocida das NPs. O mecanismo de ação antimicrobiana indica a dissociação dessas NPs na presença dos micro-organismos, com a remoção de biopolímeros da parede celular microbiana pelo PDDA, conforme visualizado por microscopia eletrônica de varredura, ocorrendo lise da membrana microbiana e liberação de compostos fosforilados para o meio extracelular. Também foram desenvolvidas neste trabalho NPs carreadoras de CLA à base de DOD e polímeros. Solução etanólica contendo CLA/DOD foi injetada em solução aquosa de CMC, formando arranjos coloidalmente estáveis e aniônicos, que posteriormente foram adicionados de solução de PDDA, para a obtenção de arranjos estáveis e catiônicos. CLA/DOD/CMC e CLA/DOD/CMC/PDDA NPs incorporaram CLA em quantidade suficiente para inibir o crescimento de M. abscessus no interior de macrófagos bem como evitar a formação de biofilmes, sendo que altas doses de CLA foram tóxicas aos macrófagos, enquanto doses menores apresentaram baixa toxicidade e boa atividade antimicrobiana. NPs catiônicas carreando CLA foram tóxicas aos macrófagos nas concentrações de PDDA testadas. A natureza particulada das CLA NPs possivelmente aumenta a retenção intracelular de CLA em comparação com CLA livre, podendo prolongar atividade da CLA contra patógenos intracelulares. Desta maneira, arranjos supramoleculares combinando lípide e polímeros, com ou sem antimicrobianos tradicionais poderão encontrar diversas aplicações nas áreas farmacêutica, médica, alimentícia e biotecnológica
Supramolecular assemblies combining cationic lipid dioctadecyldimethylammonium bromide (DOD) and polymers, such as sodium carboxymethylcellulose (CMC) and poly(diallyldimethylammonium chloride) (PDDA), were prepared as nanoparticles (NPs), in the absence or presence of traditional antibiotic, such as clarithromycin (CLA). NPs prepared by electrostatic attraction between DOD bilayer fragments (BF), CMC and PDDA were evaluated against clinical strains of multidrug resistant (MDR) microorganisms, such as Pseudomonas aeruginosa MDR, Klebsiella pneumoniae producer of KPC carbapenemase enzyme, methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans fluconazole resistant, by plating and colony forming unities counting. DOD BF/CMC/PDDA NPs display high and broad-spectrum activity against MDR microrganisms, and PDDA is the excellent biocidal component in the NPs. The mechanism of antimicrobial action shows that NPs disassembly in the presence of microrganisms, with biopolymers withdrawn from the cell wall, as observed by scanning electron microscopy, consecutively lysing bacterial membrane as determined from the leakage of inner phosphorylated compounds. In this work there have also been developed NPs, based on lipid and polymers, as carriers for CLA. Ethanolic solution co-solubilizing CLA/DOD was injected in CMC aqueous solution, yielding colloidaly stable and anionic NPs, that were further added of PDDA solution, yielding stable and cationic NPs. CLA/DOD/CMC NPs and CLA/DOD/CMC/PDDA NPs incorporated CLA at doses high enough to inhibit M. abscessus growth inside macrophages or in biofilms. Larger CLA doses were toxic to macrophages while lower CLA doses reduced toxicity to macrophages despite their high antimicrobial activity. Cationic CLA NPs exhibited substantial toxicity against macrophages at the PDDA concentrations tested. The particulate nature of these CLA NPs possibly increases intracellular CLA retention in comparison to free CLA, probably extending CLA activity against intracellular pathogens. In conclusion, supramolecular assemblies combining cationic lipid and polymers, with or without traditional antibiotics, may find multiple possibilities of applications at pharmaceutical, medical, food and biotecnological fields
Subject(s)
Polymers/analysis , Anti-Bacterial Agents/analysis , NanoparticlesABSTRACT
En busca de novedosos enfoques metodológicos para la resolución de problemas, el objetivo de este trabajo consistió en mostrar los resultados de la labor interdisciplinaria del profesorado de Microbiología y Parasitología médicas en ese sentido, basada en la creación de los siguientes materiales didácticos: Manual de respuesta inmune a los agentes biológicos para estudiantes de medicina, Sistema de habilidades para el perfeccionamiento de la asignatura y Guía didáctica de los agentes biológicos que agreden al ser humano, entre otros. El claustro de profesores estableció una nueva relación entre estudiante y docente, derivada de profundos cambios en el método de enseñanza para cumplir la exigencia interdisciplinaria en la formación académica de los educandos y contribuir a la integración de la asignatura.
Searching novel methodological approaches for the solution of problems, the objective of this work consisted on showing the results of the interdisciplinary work of the professors staff in medical Microbiology and Parasitology in that sense, based on the creation of the following didactic materials: Manual of immune response to the biological agents for medicine students, Skill system for the improvement of the subject and Didactic Guide of biological agents which attack the human being, among others. The board of professors established a new relation between students and teaching staff, derived from deep changes in the teaching method to complete the interdisciplinary demand in the academic training of students and to contribute to the integration of the subject.
Subject(s)
Parasitology , Microbiology , Students , Professional Training , FacultyABSTRACT
O Staphylococcus aureus é um patógeno extremamente versátil tanto em termos de resistência a antimicrobianos quanto em virulência. O S.aureus resistente a oxacilina (ORSA) adquire a resistência a toda a classe de beta-lactâmicos através de um cassete cromossômico (SCCmec) que carrega o gene mecA, mas pode carregar outros genes de resistência. A soma desses genes de resistência e de virulência torna o S. aureus um grave problema para hospitais do mundo inteiro, que nos últimos vem se estendendo também à comunidade. Foram estudados 50 isolados de ORSA, dentre os quais 15 pertencentes ao clone endêmico brasileiro (CEB) e 3 cepas SCCmec tipo IV isoladas entre 1995 e 1999. Adicionalmente, 32 amstras ORSA SCCmec tipo IV isoladas no Hospital de Clínicas de São PAulo...
Staphylococcus aureus is an extremely successful pathogen for it is both highly resistant to antibiotics in addition to being virulent. Methicillin-resistant Staphylococcus aureus (MRSA) acquires resistance to the beta-Iactam antibiotics through the acquisition of a chromosomal cassette (SCCmec) which carries the mecA gene, and can carry other resistance genes. The presence of these genes in S. aureus makes it a serious problem in hospitaIs worldwide. In spite of usually being restricted to the nosocomial environment, over the last few years MRSA has been spreading throughout the community. Fifty nosocomial MRSA strains were studied, including 15 belonging to the Brazilian endemic clone (BEC), 3 type IV SCCmec strains isolated between 1995-1999, and 32 type N SCCmec isolates from the "Hospital de Clínicas (HC) de São Paulo". The isolates were analyzed as to their susceptibility profile, SCCmec type, virulence and expression profile (toxins and adhesins), agr group classification and functionality, PFGE and MLST profiles. BEC isolates proved to be multiresistant to antibiotics. Type IV SCCmec strains presented a susceptibility profile to a number of drugs of different antimicrobial classes. BEC and type N SCCmec strains did not present significant differences in their virulence profiles. Only the type IV SCCmec strains isolated in 1995-1999 presented a greater virulence profile than those isolated in the HC. Type IV SCCmec strains isolated in Brazil were not highly virulent as described in other countries. Brazilian isolates usually do not possess virulence factors such as the Panton-Valentine leukocidin, exfoliative toxins and enterotoxins. On the other hand, they usually possess alpha-hemolysin and the LukED leukocidin, which is still very poorly studied that have been presented in papers like cause of serious ocular lesions and post-antimicrobial therapy diarrhea. A relation between the agr type and the virulence profile was not established, for virulence profiles were very similar even between isolates belonging to different agr groups.