Resumo

VANEGAS, María Consuelo; GONZALEZ, Lina María  e  AREVALO, Stefany Alejandra. Antibiotic activity of Bifidobacterium sp. isolated from breast milk and newborn faeces, against the main causes for foodborne illnesses. Infect. [online]. 2010, vol.14, n.4, pp.241-247. ISSN 0123-9392.

Introduction. The microbiota in the human gastrointestinal tract contains beneficial microorganisms for human health, which contribute to the regulation of colonic function and inhibition of some intestinal pathogens growth. Bifidobacterium sp. isolated from newborns and breast milk are used as probiotic microorganisms, which are useful in the prevention of infectious diseases including foodborne illnesses. Objective: To isolate and identify human Bifidobacterium sp. and to determine its antibiotic activity against important pathogens which cause foodborne illnesses in Colombia and the world. Materials and methods. 17 breast milk samples and 19 meconium and newborn faeces samples were collected from different hospitals in Bogotá. 26 presumptive Bifidobacterium strains were identified at genus level by PCR 16-23S; some strains were identified at species level by nucleic acid sequencing. The antagonistic activity of 26 Bifidobacterium sp. strains was tested against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Salmonella enteritidis ATCC 13076, Listeria monocytogenes ATCC 7644 and E. coli O157:H7 ATCC 35150. For the strains that showed a greater antibiotic activity, the inhibitory compound was analyzed using disk diffusion tests. Results. All strains amplified the expected band for genus confirmation. Strains Bif 023 and Bif 013 were identified by DNA-sequencing as Bifidobacterium breve, with 97% homology. 17 strains were able to inhibit at least one of the pathogens tested. Escherichia coli ATCC 25922 was the most inhibited. It was determined that the strain Bif 023 is highly efficient as an antagonist strain due its ability to inhibit all the evaluated pathogens. Inhibition areas showed higher diameters than expected, suggesting an enhanced antagonist capacity of native strains. Bifidobacterium sp. was isolated from breast milk, meconium and newborn faeces which confirmed that this microorganism is human microbiota. Conclusion. Due to the high antagonist activity of most isolated bacteria, they could be playing an important protective function in the newborn, in particular strains Bif 013 and Bif 023, isolated from faeces. Other studies must be performed with these organisms to determine their probiotic potential as well as their use in the biocontrol industry due their activity against foodborne pathogens.

Palavras-chave : Breast milk; antimicrobial; Bifidobacterium; probiotics; antibiotic.

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