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 (2×1000 ml), Nutrison pack (2×1000 ml) and Nutrison glass bottles (2×500 ml), and at 6 h for the Nutrison glass bottles (4×500 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.

Background: In vitro enteral feeding systems were used to investigate the effect that withdrawal of the guidewire from the feeding tube has on bacteria ascending from a patients’ stomach or intestine via the feeding tube to the giving set and nutrient container of the feeding system. Methods: Enteral feeding systems were assembled with the feeding tube running into nutrient broth contaminated with Klebsiella aerogenes. The enteral feeding tubes were held in different orientations (horizontal and vertical) to examine the effect in both prostrate and ambulant patients. The guidewire was removed either prior to or after the enteral feeding tube had been inserted into the K. aerogenes broth. Feed was then run through the systems for 24 h, with feed samples being collected from the distal (patient) end of the giving set at 0 and 24 h. Results: After 24 h, 103–108 c.f.u. (colony forming units) K. aerogenes/ml were detected in feed samples taken from the distal end of the giving set in systems where the guidewire had been removed after the enteral feeding tube had been inserted into the contaminated broth (both orientations), but K. aerogenes was not detected in samples from systems in which the guidewire had been removed before the end of the tube was inserted into the broth (both orientations). However, when the latter feed samples were enriched (i.e. incubated at 37 °C for a further 24 h to detect if very low levels of bacteria were present in the original sample), 40% of samples from systems with horizontally orientated tubes, and 20% from systems with vertically orientated tubes were positive for the test organism. K. aerogenes was not detected in any samples of feed taken from the nutrient container or just below the drip chamber. Conclusion: The results demonstrate: (i) that bacteria ascend the feeding tube over a 24‐h period (retrograde contamination) and (ii) removal of the guidewire can contribute to the colonization of the lumen of the feeding tube and distal end of the giving set with bacteria from a patients’ own flora.