PHYSIOLOGICAL COLONIZATION OF THE INTESTINAL-TRACT IN INFANTS, PATHOLOGICAL VARIATIONS AND NUTRITIONAL INFLUENCES

Background: The microbial colonization of the intestinal tract in newb orns begins during delivery. Streptococci and Escherichia coil pave th e way for the bifidobacterial dominance typical in breast-fed newborns . They provide optimal living conditions for anaerobic bifidobacteria by withdrawal of intraluminal oxygen. A mixed intestinal flora is esta blished on infant formula feeding in the infant. Bifidobacteria, Bacte roides, Enterobacteriaceae, streptococci and lactobacilli are the main genera of this mixed intestinal flora. This represents an intermediat e stage of the microflora in adults. The bifidogenic effect of mothers ' milk is based on the active substances it contains, which selectivel y enhance the growth of bifidobacteria,whereas other active substances suppress the growth of the accompanying flora. Bifidus-enhancing fact ors in breast-feeding are lactose, oligosaccharides, glycoproteins suc h as glycomacropeptide and the inoculation with bifidobacteria derivin g from the skin surface of the mother. Factors directed to the suppres sion of the accompanying microflora are antibodies, lactoferrin, lysoz yme, fatty acids and monoglycerides that act as antimicrobial substanc es and the comparatively low protein and iron content in mothers' milk . A bifidus-inhibiting colonization of the intestinal tract with patho genic germs is caused by maternal birth-canal infections,which are now known to be the most frequent reason for premature births. An increas ing number of surgical deliveries, the separation of the newborn infan t from its mother, and the generous use of antibiotics contribute to t he delayed colonization of bifidobacteria and to the development of li fe-threatening nosocomial infections. Counteractive measures against t his disastrous situation are the preferential use of bifidobacteria-pr eserving antibiotics and the inoculation of lyophilized bifidobacteria . Discussion: In a controlled study conducted by our group bifidobacte ria-inoculation in 50 preterm and term-born infants admitted to our ne onatal intensive care unit resulted in both a significantly earlier co lonization of bifidobacteria and in an earlier bifidobacterial dominan ce. It could be demonstrated that septicaemias of enteral origin did n ot any more occur after a bifidobacterial dominance was achieved.