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 (log10 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 (log10 count 7.48 vs. 7.41) or enterobacteria (log10 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.

Burden of disease & molecular epidemiology of group A rotavirus infections in India.

Rotavirus is the major cause of severe dehydrating diarrhoea in young children worldwide. Considerable research has been carried out on rotavirus disease in India. This review collated data from 46 epidemiological studies to determine rotavirus positivity rates and genotypes of infecting rotavirus strains from various settings in India. Studies on diarrhoea presenting to hospitals, neonatal rotavirus infections, symptomatic and asymptomatic infections in the community and nosocomial enteric infections were included. Rotavirus positivity rates varied greatly between different settings - diarrhoea hospitalizations (20%), neonatal infections (35%), symptomatic and asymptomatic infections in the community (15.1% and 6.3% respectively) and nosocomial enteric infections (22.5%). Among diarrhea hospitalizations, the commonest G types were G1 and G2 while commonest P types were P[8], P[6] and P[4]. Region specific neonatal infections by bovinehuman reassortants have been reported, in addition to several recently described unusual strains, which may be evidence of zoonotic infection and/or reassortment. The emergence of several new strains highlights the need for intensive strain surveillance before and after the introduction of a new vaccine.