Antagonismo de Bifidobacterium spp. e de Lactobacillus gasseri sobre Cronobacter sakazakii

• Autor(a) principal: Martins, Joice de Fátima Laureano
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2880
• topic: Cronobacter sakazakii; Bifidobacterium spp.; Antagonismo; Lactobacillus gasseri; Cronobacter sakazakii; Bifidobacterium spp.; Antagonism; Lactobacillus gasseri; CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS

The objectives of this study were to evaluate the antagonism of Lactobacillus gasseri and Bifidobacterium spp. strains on Cronobacter sakazakii strains, to elucidate the inhibitor nature, and to verify their sensitivity to 14 antibiotics commonly used in Neonatal Intensive Care Units (NICU). The experimentation was divided into three stages. At first, the sensitivity of L. gasseri, Bifidobacterium spp. and C. sakazakii to antibiotics most commonly used in NICU was evaluated. In the second step, the antagonists production in solid and in liquid media was evaluated, using either integral, cultures and cell-free supernatants. In the third stage, the inhibitor nature was determined by diffusion assays, using catalase, trypsin, and proteinase K. In the first stage of the experiments, the sensitivity of L. gasseri strains to the tested antibiotics ranged from 14.3 % for gentamicin and erythromycin to 100 % for penicillin, ampicillin, amoxicillin, meropenem, and vancomycin. Most Bifidobacterium spp. strains slowed sensitivity to antibiotics, except amikacin and erythromycin, to which all of them were resistant. Regarding the sensitivity of C. sakazakii to chemotherapeutic agents, only 43 % of the strains were sensitive to these drugs. In the second experimental group, L. gasseri strains that had been cultured in solid medium antagonized C. sakazakii consistently, where as Bifidobacterium showed little or no antagonism against the pathogen. However, planktonic cultures of either L. gasseri or Bifidobacterium produced no pathogen inhibition in well diffusion assay, regardless of the presence on the absence of their cells. The results of enzymatical assays showed that inhibition matrix of L. gasseri includes at least, active metabolites of two kinds: one of proteinaceous nature, possibly a bacteriocin, and the other one represented by hydrogen peroxide. These results indicate a for potential application of L. gasseri strains to be used as an adjunct in the treatment of infections due to their ability to antagonize C. sakazakii, a Gram-negative pathogen of high severity and increasing global interest.