Estudo da resistência a antimicrobianos em Lactobacillus delbrueckii UFV H2b20 submetido a condições de estresse

• Ano de defesa: 2006
• Autor(a) principal: Ferreira, Alessandra Barbosa
• Orientador(a): Moraes, Célia Alencar de
• Banca de defesa: Moreira, Maria Aparecida Scatamburlo , Alves, Virgínia Maria Chaves , Borges, Arnaldo Chaer , Andrade, Nélio José de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Microbiologia Agrícola
• Departamento: Associações micorrízicas; Bactérias láticas e probióticos; Biologia molecular de fungos de interesse
• País: BR
• Palavras-chave em Português: Lactobacillus delbrueckii; Resistência a antimicrobianos; Condições ambientais
• Palavras-chave em Inglês: Lactobacillus delbrueckii; Antimicrobial resistance; Environmental conditions
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::MICROBIOLOGIA::MICROBIOLOGIA APLICADA
• Link de acesso: http://locus.ufv.br/handle/123456789/5384

The effects of heat shock, acid treatment, exposure to bile salts and the presence of H2O2 on antimicrobial resistance in Lactobacillus delbrueckii UFV H2b20 were determined. Agar diffusion assays results indicated that this bacterium is resistant to vancomycin, sulphamethoxazole, colistin, some [Beta]-lactams, aminoglycosides, nitrofurans and quinolones. It is moderately susceptible to choramphenicol, tetracycline, cephalothin, ampicillin and erythromycin. L. delbrueckii UFV H2b20 can grow on high concentrations of H2O2 and complete inhibition will be observed only at 70 µg mL-1. Diferent effects on the Minimal Inhibitory Concentration (MIC) of the antimicrobials were observed when the bacterial cells were exposed to several stress conditions. Heat shock affected resistance to different aminoglycosides and [Beta]-lactams in various ways; it diminished resistance to nitrofurans and to tetracycline; however, it had no effect over resistance to choramphenicol and espiramycin. The same results were observed for acid pre-treatment at pH 3,5 for 30 min, except that it resulted in enhancement of espiramycin resistance. Cell exposure to 0,5% bile salts resulted in diminuished MICs for almost all tested antibiotics, except, apparently, furazolidone, sulphametoxol and nalidix acid, which maintained resistance to the highest concentrations tested. The presence of H2O2, 20 µg mL-1, had various effects on aminoglycosides, diminuished resistance to nitrofurans, [Beta]-lactams, tetracycline and espiramycin; however, it enhanced resistance to choramphenicol. These results demonstrate an ample diversity of responses to heat shock, acid shock, presence of H2O2, and also a general response when cells of L. delbrueckii UFV H2b20 are exposed to bile salts.