What’s growing in your feeding tubes?
We certainly watch our own food to make sure it is fresh, with no mold, and that it smells right and tastes right. But the pictures found in several of the studies mentioned below of biofilm found in enteral tubes are not very appetizing!
Several studies have now investigated the presence of this biofilm and bacteria, as well as what happens to it during feedings, and the effect on the infant.
Two older published studies looked specifically at colonization of feeding tubes, one of which also looked at blood stream infections related to the specific organism cultured from the feeding tube. These studies evaluated bacteria found in the feeding tube based on the feeding solution and dwell time of the tube.1, 2 The Hurrell study’s intent was to identify any association with feeding regimen, i.e. formula versus breast milk. They found that colonization occurred in all feeding tubes—even those from babies who were not fed through the tube. The organisms were different, but still present. Two of the organisms caused infections in the NICUs. These two organisms were Klebsiella and Serratia, and accounted for 51% of all organisms.
The Mehall study cultured tubes after seven days, and found all but one tube was colonized with various organisms, including Klebsiella. In a newer study, 94 feeding tubes were inspected for bacteria by flushing the tube with a simulated “meal.”3 This was done to evaluate how much bacteria from the biofilm would be released during a feeding. A significant amount of potentially pathogenic bacteria was found on both the proximal and distal end of the tubes in as little as six hours, although biofilm was thicker at the distal end. This suggests that the bacteria comes from the infant themselves and not from the feeding; it is likely drawn back into the tube with residual checks, which explains why the bacteria and biofilm are found in the proximal end of the tube.
Presence of bacteria from the patient was also found in an adult study.4 This group documented retrograde travel of the organisms into the feeding tube. Mehall et al showed this as well, but also found organisms that are not present in the gastrointestinal tract, suggesting contamination from another source. This was posited to be from healthcare workers or the environment and not from the feeding solution itself.
Marta Gomez and others have done a considerable amount of work on evaluating intestinal colonization of the NICU infant. In their latest study, the extension tube was cultured, as well as meconium.5 Bacteria was found in the extension tube with all types of feedings: mother’s own milk, donor milk and infant formula. Some bacteria found in the meconium was not found in the milk from the tubing. This could be because some of the bacteria is more difficult to grow out and is in greater quantities in the meconium than in the milk. Nevertheless, this study shows that the bacteria is not only in the proximal end of the NG tube, but through the connector and into the extension tubing. This also demonstrates that intestinal colonization is less influenced by the bacteria in the feeding tube than bacteria in the feeding tube being influenced by intestinal colonization. This does not make it any less potentially harmful to the infant, however. The environment in the feeding tube may cause an overgrowth of potentially pathogenic bacteria even if the source is the infant.
Petersen, Greisen & Krogfelt also evaluated the effect of probiotics on the biofilm.3 The bacteria found in the probiotics, lactobacillus and Bifidobacterium, were present in the tubes through which probiotics were administered. Otherwise, the bacteria present in those tubes exposed to probiotics and those not exposed were not significantly different. Probiotics did not protect against bacterial growth in the feeding tube. This group also evaluated the effect of antibiotic usage on the bacterial presence in the tube. Antibiotic exposure had no effect on bacterial growth, pathogenic growth, or presence of resistant organisms.
So, knowing that bacterial growth exists in feeding tubes at least within six hours of placement, what practices may be necessary to impact the potential effect of this bacterial growth? Hurrell et al investigated the effect of silver-impregnated tubes without success in eliminating the biofilm formation.6 Replacing feeding tubes even as often as every 24 hours has minimal advantage and does not avoid biofilm formation since it is found within six hours of placement.
Berthelot et al 2001 reported on an infectious outbreak in France.7 This included digestive tract colonization of Klebsiella oxytoca in 24 infants. One of these infants died and others were clinically ill. The colonization and cross-contamination was eventually eradicated with the implementation and enforcement of hand hygiene and use of gloves when handling feeding tubes.
Ultimately, studies should focus on the effect of more frequent feeding tube changes (with every feeding or every 24 hours) and the clinical effect on the infant. Outcomes should focus on signs of distress with more frequent feeding tube changes, feeding intolerance, incidence of necrotizing enterocolitis, sepsis, and cost. Questions have been raised about the value of checking residuals, which may increase the collection of the biofilm and offer questionable clinical relevance. Further evaluation of this is already underway.3
1. Hurrell E, Kucerova E, Loughlin M, Caubilla-Barron J, Hilton A, Armstrong R, et al. Neonatal enteral feeding tubes as loci for colonization by members of the Enterobacteriaceae. BMC Infectious Diseases. 2009; 9:146.
2. Mehall JR, Kite CA, Saltzman DA, Wallett T, Jackson RJ, Smith SD. Prospective study of the incidence and complications of bacterial contamination of enteral feeding in neonates. Journal of Pediatric Surgery. 2002; 37(8):1177-1182.
3. Petersen, SM, Greisen G, and Krogfelt KA. “Nasogastric feeding tubes from a neonatal department yield high concentrations of potentially pathogenic bacteria even 1 d after insertion.” Pediatric research (2016).
4. Mathus-Vliegen EMH, Brediu MWJ, Binnekade JM. Analysis of sites of bacterial contamination in an enteral feeding system. Journal of Prenteral and Enteral Nutrition. 2006;30(6):519-525.
5. Gómez, M, et al. “Early Gut Colonization of Preterm Infants: Effect of Enteral Feeding Tubes.” Journal of pediatric gastroenterology and nutrition 62.6 (2016): 893-900.
6. Hurrell, E., et al. “Biofilm formation on enteral feeding tubes by Cronobacter sakazakii, Salmonella serovars and other Enterobacteriaceae.” International journal of food microbiology 136.2 (2009): 227-231.
7. Berthelot P, Grattard F, Patural H, Ros A, Jelassi-Saoudin H, Pozzetto B, et al. Nosocomial colonization of premature babies with Kelbsiella Oxytoca: Probable role of enteral feeding procedure in transmission and control of the outbreak with the use of gloves. Infection Control and Hospital Epidemiology. 2001;22:148-151.