RESUMO
Bacteroides fragilis is the most commonly isolated anaerobic bacteria from infectious processes. Several virulence traits contribute to the pathogenic nature of this bacterium, including the ability to tolerate the high concentrations of bile found in the gastrointestinal tract (GIT). The activity of bile salts is similar to detergents and may lead to membrane permeabilization and cell death. Modulation of outer membrane proteins (OMPs) is considered a crucial event to bile salts resistance. The primary objective of the current work was to identify B. fragilis proteins associated with the stress induced by high concentration of bile salts. The outer membrane of B. fragilis strain 638R was isolated after growth either in the presence of 2% conjugated bile salts or without bile salts. The membrane fractions were separated on SDS-PAGE and analyzed by ESI-Q/TOF tandem mass spectrometry. A total of 37 proteins were identified; among them nine were found to be expressed exclusively in the absence of bile salts whereas eight proteins were expressed only in the presence of bile salts. These proteins are related to cellular functions such as transport through membrane, nutrient uptake, and protein-protein interactions. This study demonstrates the alteration of OMPs composition in B. fragilis during bile salts stress resistance and adaptation to environmental changes. Proteomics of OMPs was also shown to be a useful approach in the identification of new targets for functional analyses.
Assuntos
Proteínas da Membrana Bacteriana Externa/isolamento & purificação , Bacteroides fragilis/efeitos dos fármacos , Ácidos e Sais Biliares/farmacologia , Proteínas de Transporte/isolamento & purificação , Membrana Celular/efeitos dos fármacos , Estresse Fisiológico/genética , Adaptação Fisiológica , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , Bacteroides fragilis/química , Bacteroides fragilis/crescimento & desenvolvimento , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Membrana Celular/química , Meios de Cultura/química , Expressão Gênica , Ontologia Genética , Anotação de Sequência Molecular , Proteômica/métodosRESUMO
INTRODUCTION: Clostridium baratii is rarely associated with human diseases. Infection is usuallcaused by ingestion of contaminated food, and infant botulism is the most common clinical presentation. CASE REPORT: Here we report a case of pneumonia by a non-toxigenic strain of C. baratii in an Alzheimer 70-year-old male with sepsis in Rio de Janeiro, Brazil. The micro-organism was identified by phenotypical tests, mass spectrometry (MALDI-TOF), DNA amplification (PCR) and sequencing of the 16S rRNA gene. Testing for the presence of botulinum F toxin was made using multiplex PCR. Bioassay for a large number of colonies was performed in mice to evaluate the production of any lethal toxin, but the results were negative. CONCLUSION: To our knowledge, there are no cases of C. baratii infection reported in Brazil and we highlight the importance of anaerobic lab tests in the standard routine of diagnosis.