Abundance of Bifidobacterium species in the infant gut microbiota and associations with maternal-infant characteristics in Dhaka, Bangladesh

The early infant gut microbiota is dominated by bifidobacteria, but there is substantial variation at the (sub)species level. Patterns of postnatal Bifidobacterium subspecies colonization in low or middle-income countries have not been widely studied. We used (sub)species-specific qPCR to quantify B. infantis, B. longum , and B. breve in stool samples from 1132 infants (0-6 months) in urban Dhaka, Bangladesh. B. infantis absolute abundance started low but increased in the first two months, whereas B. longum and B. breve abundances remained comparatively low. B. infantis emerged earlier in infants delivered by C-section, but by ∼2 months of age, infants delivered by C-section or vaginally had similar B. infantis abundances. Infant antibiotic exposure, feeding patterns, and maternal stool B. infantis were not associated with infant B. infantis . In settings where B. infantis is widespread, its patterns of postnatal colonization can be used to inform the design of targeted microbiota-modifying interventions in infancy.