Faecal bifidobacteria in Indian neonates & the effect of asymptomatic rotavirus infection during the first month of life

BACKGROUND & OBJECTIVES: Bifidobacteria colonize the gut after the first week of life and remain an important component of the gut microbiota in infancy. This study was carried out to characterize the diversity and number of bifidobacteria colonizing the gut in Indian neonates and to investigate whether asymptomatic infection with rotavirus in the first month of life affected gut colonization by bidifobacteria. METHODS: DNA was isolated from faeces of 14 term-born neonates who were under surveillance for rotavirus infection. Bacterial and bifidobacterial diversity was evaluated by temporal temperature gradient electrophoresis (TTGE) of 16S rDNA amplified using total bacteria and bifidobacteria-specific primers. Real time PCR, targeting 16S rDNA, was used to quantitate faecal bifidobacteria and enterobacteria. RESULTS: TTGE of conserved bacterial 16S rDNA showed 3 dominant bands of which Escherichia coli (family Enterobacteriaceae) and Bifidobacterium (family Bifidobacteriaceae) were constant. TTGE of Bifidobacterium genus-specific DNA showed a single band in all neonates identified by sequencing as Bifidobacterium longum subsp. infantis. Faecal bifidobacterial counts (log(10) cfu/g faeces) ranged from 6.1 to 9.3 and enterobacterial counts from 6.3 to 9.5. Neonates without and with rotavirus infection in the first week of life did not show significant differences in the median count of bifidobacteria (log(10) count 7.48 vs. 7.41) or enterobacteria (log(10) count 8.79 vs. 7.92). INTERPRETATION & CONCLUSIONS: B. longum subsp. infantis was the sole bifidobacterial species colonizing the gut of Indian neonates. Asymptomatic rotavirus infection in the first month of life was not associated with alteration in faecal bifidobacteria or enterobacteria.