[Analyzing Colonization of Bifidobacteria in Infants with Real-time Fluorescent Quantitative PCR].

ABSTRACT

OBJECTIVES: In order to know how intestinal Bifidobacteria community could be built in the infants and whether the environmental factors could affect them, the present study was conducted to characterizethe species composition and trace the quantitative changes of intestinal Bifidobacteria of the infants in their early stages with non-culture dependent molecular method. The possible association of Bifidobacteria community of the infants with their health was also discussed. METHODS: Total 16 of full-term newborn infants born between March and April 2013 were recruited for the present study. Fecal samples were collected from them at 1 day, 2 days, 4 days, 7 days, 10 days, 14 days, 28 days, 3 months, 6 months and 1 year after birth. Real-time fluorescent quantitative PCR with genus and species specific premiers was used to detect Bifidobacteria and 8 predominate species in human intestine qualitatively and quantitatively present in these collected fecal samples. RESULTS: Total 136 fecal sample were collected and Bifidobacteria were detected from 93.4% (127/136) of them with the concentration of 1.0×10 5 to 1.0×10 11 CFU/g. Bifidobacteria were found in 83.3% of the fecal samples collected from the first day after birth with more than about 10 5 CFU/g. However, Bifidobacteria were detected relative low until 14 days and were taxonomically belonged only to one or two species. Bifidobacteria were found in almost 100% of the fecal samples collected after birth 28 days with more than 108 CFU/g, and the detected species of Bifidobacteria was increased to 3 species after 28 days to 6 months. All of the fecal samples collected from one year had more than 3 species of Bifidobacteria with high cell counts. Among the detected Bifidobacteria were B.breve 92.1%, B.infantis 66.1%, B. catenulatum 59.8%, B. bifidum 25.2%, B. longum 24.4%, B.dentium 13.4%, B.angulatum 5.5% and B.adolescentis 1.6%, respectively. CONCLUSIONS: The detected Bifidobacteria greatly varied qualitatively and quantitatively after birth to one year which could be considered as the important and sensitive period for Bifidobacteria to colonize and built its communityin the infants. Different from previous studies, the colonization of Bifidobacteria in the tested infants was found delayed and the composition and diversity of Bifidobacteria species was different from other studies. These might result from different deliveryway, feeding pattern and other environmental factors related to the tested infants.