Gut overgrowth with abnormal flora: the missing link in parenteral nutrition-related sepsis in surgical neonates

Patients receiving parenteral nutrition are at risk of septicaemia. Intestinal dysmotility and impaired gut immunity due to parenteral nutrition promote bacterial overgrowth. Gut overgrowth with aerobic Gram-negative bacilli (AGNB) impairs systemic immunity. The aim of this study was to determine the potential role of gut overgrowth with AGNB in the pathogenesis of septicaemia related to parenteral nutrition.

A prospective 5 y study of surgical infants less than 6 months of age was undertaken. Surveillance samples of the oropharynx and gut were obtained at the start of parenteral nutrition and thereafter twice weekly, to detect AGNB carriage. Blood cultures were taken on clinical indication only.

Two-hundred and eight infants received parenteral nutrition for 6271 days (median 13 days, range 1-512 days). The incidence of AGNB carriage was 42%, whilst the septicaemia rate was 15%. Eighty-four percent of septicaemic infants carried AGNB, whilst 16% never carried AGNB (P<0.005). Carriage developed significantly earlier than septicaemia.

The incidence of septicaemia was significantly greater in the subset of abnormal carriers. Although gut overgrowth with abnormal flora reflects illness severity, the fact that it preceded septicaemia implicates AGNB overgrowth, per se, as a contributory factor in the development of septicaemia related to parenteral nutrition. Prevention is unlikely to be successful if it ignores the abnormal flora.