Contamination of Enteral Nutrition Systems during Prolonged Intermittent Use

Abstract

Two related studies were done to determine the incidence of bacterial contamination in enteral delivery systems that were used for 15 and 7.5 hr, rinsed after each use, and reused daily in vitro for 7 and 5 days, respectively. In the first study, systems infusing either a premixed formula (Ensure) or a hand-mixed formula (Vivonex) did not show bacterial growth until the 4th day, 1.0-2.0 × 10 colony-forming units per milliliter (CFU/ml) of Staphylococcus epidermidis. Thereafter there was sporadic growth of different organisms but never increasing growth during the 7 days of infusion. In the second study, systems with Ensure were initially contaminated with Staphylococcus aureus and Escherichia coli and reused for 5 days. S. aureus was eliminated by rinsing, but E. coli persisted in the delivery system at concentrations of 10³-10⁶ CFU/ml. We conclude that clean enteral nutrition systems can be rinsed after short-infusion periods and reused up to 7 days in vitro without significant contamination; however, once a bag has become heavily contaminated some bacteria cannot be eradicated from the system by rinsing. (Journal of Parenteral and Enteral Nutrition 13:23-25, 1989)