The microbiome of plastic tubes in children

Petersen SM, et al. Nasogastric feeding tubes from a neonatal department yield high concentrations of potentially pathogenic bacteria – even one day after insertion. Pediatr Res. 2016.  These authors cultured 94 nasogastric feeding tubes from 34 preterm infants. 1 ml of saline was washed down the tubes after removing them from the babies, and only organisms with more than 1000 CFU/mL were counted. They found 178 that passed this threshold. 89% of the tubes grew things other than probiotics, and this was not related to how long the tubes were in place, they became contaminated very quickly after insertion. Almost all of the organisms were potential pathogens, Coagulase negative staph, enterococci, Gram-negative rods, S aureus.

They also did scanning EM to look at the bioflims, I think they did this on just one NG tube (singular and plural terms are used), and found it to be coated with a “nice” thick biofilm. Although the authors did not show that contamination of the NG tubes led to clinical illness, reducing it would have to be a good thing, I think, as many of these organisms were pathogens, or at least potential pathogens. The authors put it this way:

Our findings and the existing literature suggest that resident NG-tubes should be handled with the same hygiene standards as materials containing fecal matter.

Gilbert RE, et al. Impregnated central venous catheters for prevention of bloodstream infection in children (the CATCH trial): a randomised controlled trial. Lancet. 2016;387(10029):1732-42.

Intravenous catheters are even more of a problem, there are apparently 56 RCTs of various impregnated catheters in adults, and several systematic reviews which show that they are effective at reducing invasive infections. Heparin-bonded catheters seem to be effective, maybe because they prevent the development of biofilms, or maybe there is a direct effect of heparin, or of the agent used to bond the heparin, benzalkonium chloride. Antibiotic-bonded catheters also seem effective, the usual agents are minocycline-rifampicin, which has the advantage that they are not much used as systemic treatments, so there is less worry about selecting resistant organisms.

In this new trial, about 1500 children in PICUs around England were recruited and randomized to get either standard catheters, a catheter with heparin bonding, or a catheter with minocycline-rifampin bonding. All clinical care was unchanged, except that they took an extra 0.5 mL of blood whenever the child needed to have a blood culture.

Heparin didn’t work.

The antibiotic-bonded catheters led to a reduction in invasive sepsis from 3.6% in the other two groups to 1% with the antibiotic-bonded catheters. To present the data another way the blood stream infections per 1000 catheter days were over 8 in the control and heparin groups, and 3.3 in the antibiotic group.

As far as I can tell the only down-side of these catheters is the additional cost. But that should be cancelled out, I would think, by an NNT of about 50, i.e. for every 50 antibiotic bonded catheters there is one less invasive bloodstream infection.

Now we need a neonatal study. Why? Well, our rates of infection in the very preterm baby are much higher than this, the bacteriology is different (they had a total of 42 infections, with only 6 being due to CoNS), toxicity might be different if there is any antibiotic which leaches into the circulation, but the cost implications might be much more positive, if the same relative reduction in sepsis is seen, the benefits could be enormous.

The relevant Cochrane review is quite recent (last September) and found only one small trial in newborns, (n=98). A trial with enough power to address safety would be a boon to neonatology.


About Keith Barrington

I am a neonatologist and clinical researcher at Sainte Justine University Health Center in Montréal
This entry was posted in Neonatal Research and tagged , , . Bookmark the permalink.

2 Responses to The microbiome of plastic tubes in children

  1. bpairtbob says:

    There is at least one randomised control trial of antibiotic coated central venous lines ongoing.

  2. There is a large UK neonatal trial in progress, actively recruiting ahead of schedule led by Ruth Gilbert (CATCH) and Sam Oddie (Bradford, Neonatal) – you can find more information here

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.