BACTERIAL-COLONIZATION OF ENTERAL FEEDING TUBES

An in-vitro model system was used to determine the number of bacteria infused into a 'patient' when three types of polyurethane enteral feeding-tubes that had been experimentally contaminated with feed containing K. aerogenes on day 1, were then perfused with sterile feed for periods of 8 h on three consecutive days (days 2-4). The tubes were syringed with 20 ml sterile water at regular intervals. Viable counts were made on syringe washings, feed collected from the ends of the tubes and feed from the nutrient containers. On day 1, the total number of K. aerogenes in feed samples collected from the nutrient containers and the ends of the tubes rose from 10(2) to 10(3)-10(4) cfu ml-1 over 8 h. On days 2-4 no organisms were detected in the feed samples from the nutrient containers whereas viable counts on feed samples collected from the tubes and syringe washings rose from 10(4) to 10(7) and from 10(1) to 10(7) cfu ml-1 respectively. It can be concluded that a single incidence of feed contamination could lead to a patient receiving contaminated feed from an enteral feeding-tube colonized with bacteria which will not be detected by normal monitoring of the remainder of the system.