Abstract
Bifidobacteria are obligately anaerobic, Gram-positive, rod-shaped bacteria which predominate in human intestinal microbiota during early infancy. Although they are considered to be “vertically” transferred from mother to infant, little is known to substantiate this view. In this context, we performed Pulsed-Field Gel Electrophoresis (PFGE) on strains of Bifidobacterium longum subsp. longum isolated from fecal samples of 5 mother-infant pairs. Our PFGE analysis revealed that strains isolated from 3 of the pairs had almost identical PFGE patterns within pairs. Subsequently, we investigated aerobic and microaerophilic survival of the maternal strains. The strains maintained their original population on agar plate medium for up to 6 h and 18 h under aerobic and microaerophilic conditions, respectively; they died out on a human palm within 3 h; and it took more than 24 h for them to die out, even under an aerobic condition, if they were desiccated. This evidence suggests that the vertical transfer of bifidobacteria occurs via the birth canal or surrounding atmosphere, equipment, or clothing rather than the hand or fingers.
