Formação de biofilme por espécies de Streptococcus

• Autor(a) principal: Carvalho, Guilherme da Silva Lourenço
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/14390
• topic: Biofilm; Streptococcus; Virulence; Biofilme; Streptococcus; Virulência; Streptococcus; Biofilmes; Virulência; CNPQ::CIENCIAS BIOLOGICAS::MICROBIOLOGIA::BIOLOGIA E FISIOLOGIA DOS MICROORGANISMOS

Streptococcus includes clinically important species that are responsible for a wide variety of infections in human and animals. The biofilms formation has been identified as responsible for the success on the persistence of these microorganisms in some infections. The aim of this study was to analyze the biofilm formation by 19 streptococcal species associated with human and animal infections. Biofilms formation was determined in BHI, THB and HIB and in the presence of glucose or sucrose (0,25% - 1,0%). The biofilms were evaluated by a semiquantitative method of crystal violet. The susceptibility to ampicillin and erythromycin were assessed by viability assays using Alamar blue and the semiquantitative method of crystal violet. The presence of DNA and proteins in the extracellular polymeric substance was determined by detachment assays, after treatment with DNaseI or proteinase K. The biofilms structural architecture and the distribution of live and dead cells were examined by optical microscopy and confocal laser scanning microscopy. All strains were biofilms producers. The species S. agalactiae and S. pyogenes were characterized as strong producers, according to the previous defined standards (DO570nm> 1.0). The biofilm formed in BHI and HIB by S. canis was significantly higher (p <0.05) than in THB. The addition of sugars, for most species, resulted in significant increase in biomass of biofilms (p <0.05). However, this increase was not proportional to the increase of concentration. The more favorable glucose concentrations varied between species, however, most had higher biomass in biofilms formed in HIB medium plus 0.25% glucose. In contrast to sucrose, the results of most of the samples were similar in different concentrations. For most samples, the biofilm inhibitory concentration (BIC) was found as > 640 mg / mL. The species showing lower BICs were: S. suis, 80 mg / mL of ampicillin or erythromycin, S. porci 640 g / mL of ampicillin and S. pyogenes, 640 mg / mL of erythromycin. Most species showed DO values similar to the control biofilm in the absence of antimicrobials. Our data revealed that both ampicillin and erythromycin in subMICs induced the formation of streptococcal biofilm significantly (p <0.05). Treatment with proteinase K caused the biomass reduction in most of most the strains. However, S. agalatiae, S. dysgalactiae subsp equisimilis, S. iniae, S. mutans, S. parauberis, S. pyogenes and S. porcinus showed the significative values, suggesting the presence of protein-rich structures. S. agalatiae, S. dysgalactiae subsp equisimilis, S. equi subsp equi, S. urinalis and S. pyogenes showed biofilm detachment due to DNaseI treatment, but only the species S. agalactiae and S. pyogenes showed significant values. S. agalactiae and S. pyogenes showed greater biomass in confocal and optical images, presenting long filaments of extracellular DNA. The CLSM also revealed variations in the relationship between the amount of dead and living cells, suggesting maturation times species-specific. Although additional studies are needed, the data showed particular characteristics on biofilm formation.