Nutritional implications of gut overgrowth and selective decontamination of the digestive tract.

Patients requiring parenteral nutrition (PN) are at risk of infection. Impaired immunity due to an underlying disease process and/or malnutrition, combined with therapeutic interventions including PN, and the presence of a foreign body, the intravenous catheter, renders them prone to septicaemia (Pun & Reen, 1992). Recent studies suggest that this septicaemia may be primarily due to gut-derived micro-organisms, rather than to external contamination of the intravenous catheter (Kurkchubasche el al. 1992; Pierro et al. 1996). Previous work has shown that PN has a detrimental effect on mucosal defences (Li et al. 1995; Kudsk et al. 1996), and impairs gut motility (Vantrappen et al. 1977) and biliary flow (Jawaheer et al. 1995). This promotes small intestinal bacterial overgrowth, particularly with aerobic Gram-negative bacilli (AGNB), and this overgrowth has been identified as a risk factor for impaired systemic immunity (Marshall et al. 1987) via endotoxin-induced liver dysfunction (Billiar et al. 1988). Suppression of both mucosal and systemic immunity is required for the development of sepsis and septicaemia (Alverdy & Burke, 1992). A prospective 5-year study in a large homogeneous population of surgical infants of < 6 months postnatal age was undertaken to determine the importance of gut overgrowth with AGNB in the pathogenesis of PN-related septic complications.