Introduction Fine bore nasogastric tube (NGT) blockages can result in delays in nutrient provision and poor patient experience. Biofilm development on the internal lumen wall of the tube has the potential to initiate such blockages, but has been little investigated.

Method The study aimed to investigate the rate of biofilm formation in sterile NGTs in vitro . Short sections of new sterile NGTs were placed in a 6-well microtiter plate and immersed in a standard commercial enteral feed to which an inoculum was added. This was incubated at 37°C. The inocula used in the study were prepared from strains ofEscherichia coliand Pseudomonas aeruginosa.The NGT sections were removed after 0, 15, 30, 60, 120, 240 and 1440 min. Culturable cells were quantified by colony forming units (CFU), and bacterial viability was measured by cell elongation (CE). In addition, the sections were examined directly using episcopic differential interference contrast (EDIC) microscopy.

Results Results from 3 sections at each time point from 11 NGTs for the E. coliinoculum and 3 NGTs for the P. aeruginosainoculum are presented. Mean CE and CFU counts for both the E. coliand P. aeruginosainocula increase from 0 to 1440 min. This demonstrates bacteria attach to the NGT within 15 min of introduction, with generally increasing colonisation over the subsequent time measured, and retain viability. EDIC microscopy was successfully used to directly examine the NGT surface, showing evidence of extensive biofilm formation.

Conclusion The study has demonstrated the development of bacterial biofilms (evidenced by CE, CFU and microscopy) on NGT lumen walls over a 24 h period in the laboratory setting. The presence of biofilms may have the potential to interrupt flow through the lumen and contribute to blockage development. Further studies plan to examine the effect of flushing with water on biofilm development, in particular considering the use of sterile and tap water flushes, and to investigate biofilm presence in used NGTs retrieved from adult patients in the course of their normal clinical care.

Disclosure of interest None Declared.