Influência de antimicrobianos, concentrações de glicose e variações de pH na produção de biofilmes por isolados de Escherichia coli obtidos de mastite bovina

• Autor(a) principal: Costa, João Carlos Miguel
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5082
• topic: Escherichia coli; Biofilmes; Mastite; Escherichia Coli; Biofilm; Mastitis; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA::MEDICINA VETERINARIA PREVENTIVA

Escherichia coli is a microorganism of environmental origin highly adaptive and its ability to form biofilms under certain conditions may be critical for their resistance to antimicrobial treatments, which makes E. coli an important causative agent of mastitis. We studied 27 isolates of E. coli producing biofilms obtained from clinical mastitis belong to the collection of the Federal University of Viçosa. The isolates were tested for sensitivity to antibiotics used to treat mastitis, both for planktonic cells, by assessing the minimal inhibitory concentration - MIC as for the sessile, assessing the minimal biofilm eradication concentration - MBEC. In addition, all isolates were grown in minimal media containing different pH values and glucose concentrations and to assess the influence of these factors in producing biofilms. Similarly underwent the isolates at concentrations of antimicrobial sub-inhibitory to verify the possible induction of these doses on the formation of biofilms. Four isolates were chosen, large and weak biofilm producers, to be analyzed by scanning electron microscopy - SEM. The results revealed a high rate of sensitivity, confirmed by the evaluation of MIC, in which only four (14.8%) isolates had high MIC values ranging from 4 to 10 &#956;g / mL and were classified as resistant. However, for the remaining isolates (85.2%) were lower, ranging from 0.125 to 2 &#956;g/mL classified as sensitive. The evaluation of MBEC indicated that the concentration of antibiotic required to eliminate the sessile cells ranged from the 100 &#956;g/mL 500 &#956;g/mL. Gentamicin and enrofloxacin were possible inducers of biofilm formation, respectively, at 0.0312 and 0.0125 &#956;g / mL. MBEC values were significantly higher in isolated large and moderate-producing biofilms in relation to isolated weak biofilm producers (p < 0.001). There was no correlation between the values of MCEC and MIC (p > 0.05). The biofilm production was higher (p < 0.001) in minimal media with limited glucose (0.5%) and pH values further away from neutrality (pH 5.5 and pH 8, 5) in relation to the minimum means-rich glucose (2,5% and 3.5%) and pH close to neutrality (pH 6.5 and 7,5). The presence of biofilms was confirmed in isolates submitted to the SEM, through visualization of adhered cells and the presence of exopolysaccharides, characterizing the typical architecture of biofilms. The knowledge of the characteristics of biofilm production in isolates of E. coli causing mastitis is an important tool for establishing more efficient treatment strategies.