The Acquisition of the Normal Microflora of the Gastrointestinal Tract

Abstract

The birth of a mammal must be a moment of celebration in the microbial world. A new, potential host emerges from the uterus where it has been protected during development from contact with bacteria, fungi and protozoa. During passage of the young animal through the birth canal, members of the vaginal microflora have the opportunity to contaminate the pristine surfaces of the infant. At the moment of birth, or shortly thereafter, microbes in faeces that have been involuntarily expelled by the mother during labour, and microbes that are present in the air or on inanimate materials enter the germfree ecosystems of the neonate and proliferate to a dramatic extent. Suckling, licking (kissing) and grooming (caressing) of the infant after birth enables transfer of skin and oral microbes from adult to neonate to occur. It might be thought, indeed, that the positioning of the orifice of the birth canal in close vicinity to the anus, and the nature of parental expressions of caring are of microbiological design, since they ensure the transmission of microbes comprising the normal microflora from one generation to the next (Carlsson and Gothefors 1975; Brunel and Gouet 1982; Brunel and Gouet 1989; Tannock et al. 1990b).