Background: The purpose of this study was to compare the risks of introducing microbial contamination when assembling and running two commonly used, ready-to-hang, enteral feeding systems (Nutrison glass bottles and Steriflo) with a newly introduced system (Nutrison pack). Methods: The nutrient container tops of all systems were deliberately touched during assembly by a researcher wearing gloves contaminated with Klebsiella aerogenes. After touching, half the containers were immediately connected to giving sets, the other half were disinfected using alcohol wipes before connection to the giving sets. Systems were run for 24 h, with a change of nutrient container at 12 h for the Steriflo (2x1000 ml), Nutrison pack (2x1000 ml) and Nutrison glass bottles (2x500 ml), and at 6 h for the Nutrison glass bottles (4x500 ml). Feed samples for microbiological analysis were taken from feed in the systems at the 0 h assembly, and from residual feed in all discarded nutrient containers. Each protocol was repeated five times. Results: The percentage of feed samples in which K. aerogenes was detected reduced significantly from 68% for non-disinfected Nutrison glass bottles changed every 6 h, to 59% after disinfection, and from 51% to 0% after disinfection of Steriflo systems (Mann-Whitney, P< 0.05). For Nutrison glass bottles changed every 12 h the fall from 51% with no disinfection to 49% after disinfection was not significant (Mann-Whitney, P< 0.05). Nutrison packs were not disinfected and yet K. aerogenes was only detected in 2% of feed samples. This rate of contamination was significantly less than that for all the other non-disinfected systems (Mann-Whitney, P< 0.05). Conclusion: The results show a reduction in the incidence of bacterial contamination of the feed samples when systems were disinfected subsequent to being exposed to faulty handling procedures, thus supporting manufacturers recommendations to disinfect systems during assembly. The results particularly highlight the important role played by system design in reducing the levels and incidence of bacterial contamination of enteral tube feeds.