Probiotic Use in Children

Rosemary J. Young, MS, RN, Shari Huffman, MN, RN, CPNP

J Pediatr Health Care. 2003;17(6) 

In This Article

Intestinal Flora

The intestinal tract of the human fetus is sterile but is exposed to many different species of microorganisms after birth. Primary portals of entry for these bacteria include the birth canal during delivery and contact with other humans and the surrounding environment. After birth, many factors influence the types and quantities of intestinal microflora of the infant. Besides extrinsic factors such as the mother's dietary intake or use of probiotics, type of birth (vaginal or surgical), gestational age, and primary source of nutrition (bottle or breast fed), intrinsic factors including underlying neonatal health, immunologic status, gastrointestinal transit time, pH, and stress all affect the process of colonization and the types of organisms established (Kopp-Hoolihan, 2001; Mackie, Sghir, & Gaskins, 1999). Because they are not exposed during birth to maternal flora, infants born via cesarean section may have delayed colonization, as well as a greater acquisition of environmental flora, than do vaginally born infants. It has been hypothesized that this situation may lead to a less than "normal" enteric flora and the potential for the development of later gastrointestinal and systemic immunological problems (Favier, Vaughan, De Vos, & Akkermans, 2002).

The predominate organisms in formula-fed, full-term infants are initially Enterobacter species, whereas full-term infants receiving mother's breast milk have higher concentrations of bifidobacteria in the first weeks of life. Establishment of bifidobacteria is promoted by the ingestion of human milk. Although bifidobacterium also becomes the dominant organism in formula-fed infants by 6 months of age, these infants have significantly fewer numbers of these organisms and a more complex microflora. By 12 months, colonic bacterial populations in both groups are similar and are close in composition to the adult large bowel (Dai & Walker, 1999).

Premature infants and term infants requiring intensive care are slower to acquire bifidobacteria flora. Premature infants are also more susceptible to pathogenic colonization, which predisposes them to infection. Animal studies have shown that bacteria considered to be nonpathogenic to adults may be harmful in the early human neonatal stages (Wagner, Warner, Roberts, Farmer, & Balish, 1997), but beneficial intestinal bacteria have been shown to stimulate normal mucosal defense systems and inhibit pathogenic organisms (Dai & Walker, 1999). Thus, the idea of controlling the process of newborn intestinal colonization is intriguing. Studies of the neonatal intestinal flora and the differences in colonization patterns have influenced feeding practices and, more recently, formula development. Infant formulas containing both pre- and probiotics are currently available in Europe, Asia, and South America. Deliberate manipulation and control of neonatal gut colonization may someday be a common approach to preventing and treating various gastrointestinal diseases (Dai & Walker, 1999).

Once established, the intestinal flora is relatively stable throughout life and difficult to change permanently. It is recognized as native and typically beneficial to that individual. In adults, Bacteroides species represent the most prevalent groups in the large intestine, but others are also present, including bifidobacteria, lactobaccilli, staphylococcus, enterobacteria, streptococci, and clostridia species (see Figure). Temporary alterations in intestinal flora are related to the state of the host and can be induced by antibiotic therapy, radiation or chemotherapy, and alterations in host immunity. The most common alteration of intestinal flora in children occurs with antimicrobial therapy, especially with broad-spectrum antibiotics (Vanderhoof & Young, 1998). Because children receive antibiotics rather often and are quite prone to gastrointestinal disease in the first few years of life, use of probiotics in children remains an area of significant interest and research.

Figure.

Microorganisms in the gastrointestinal tract.

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