Antagonismo de Bifidobacterium spp. e de Lactobacillus gasseri sobre Cronobacter sakazakii
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Data
2010-02-10
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Universidade Federal de Viçosa
Resumo
Os objetivos deste trabalho foram avaliar o antagonismo de estirpes de Lactobacillus gasseri e Bifidobacterium spp. sobre estirpes do patógeno
Cronobacter sakazakii, elucidar a natureza do inibidor e verificar a sensibilidade dessas estirpes aos 14 antibióticos comumente utilizados em Unidade de Terapia (UTI) neonatal. A experimentação foi divida em três etapas. Na primeira, foi avaliada a sensibilidade de L. gasseri, Bifidobacterium spp. e C. sakazakii aos antibióticos mais comumente empregados em UTI neonatal. Na segunda etapa, foi examinada a produção de antagonistas em meio sólido e a produção de antagonistas em meio líquido, que foi conduzida com o emprego de células líquidas integrais e uso de sobrenadante livre de células. Na terceira etapa, foi determinada a natureza do inibidor segundo ensaios de difusão, utilizando-se catalase e tripsina e proteinase K. Na primeira etapa dos experimentos, a sensibilidade das estirpes de L. gasseri aos diversos antibióticos testados variou entre 14,3 % de estirpes sensíveis a gentamicina e eritromicina, e 100 %, no caso
de penicilina, ampicilina, amoxicilina, meropenem e vancomicina. A maioria
das estirpes de Bifidobacterium spp. apresentou-se sensível aos antibióticos,
à exceção da amicacina e eritromicina, às quais todas foram resistentes. Em
relação à sensibilidade de C. sakazakii aos quimioterápicos, somente 43 %
das estirpes se apresentaram sensíveis a esses medicamentos. No segundo
agrupamento experimental, estirpes de L. gasseri desenvolvendo-se em meio sólido antagonizaram consistentemente o patógeno C. sakazakii, ao passo que Bifidobacterium apresentaram pouco ou nenhum antagonismo sobre o patógeno. Entretanto, culturas planctônicas de L. gasseri e de Bifidobacterium não produziram inibição do patógeno em ensaios de difusão em placa, tanto na presença quanto na ausência de suas células. Os resultados dos ensaios enzimáticos evidenciaram que a matriz de inibição de L. gasseri inclui metabólitos ativos de, pelo menos, duas naturezas: uma delas proteíca, possivelmente uma bacteriocina; e a outra representada pelo peróxido de hidrogênio. Indicaram também potencial de aplicação de estirpes L. gasseri como adjunto no tratamento de infecções, notadamente pela capacidade de antagonizar C. sakazakii, um patógeno Gram-negativo de elevada severidade e de crescente interesse mundial.
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.
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.
Descrição
Palavras-chave
Cronobacter sakazakii, Bifidobacterium spp., Antagonismo, Lactobacillus gasseri, Cronobacter sakazakii, Bifidobacterium spp., Antagonism, Lactobacillus gasseri
Citação
MARTINS, Joice de Fátima Laureano. Antagonism of Bifidobacterium spp. and Lactobacillus gasseri on the Cronobacter sakazakii. 2010. 97 f. Dissertação (Mestrado em Ciência de Alimentos; Tecnologia de Alimentos; Engenharia de Alimentos) - Universidade Federal de Viçosa, Viçosa, 2010.