Short-duration selective decontamination of the digestive tract infection control does not contribute to increased antimicrobial resistance burden in a pilot cluster randomised trial (the ARCTIC Study)

Objective
Selective decontamination of the digestive tract (SDD) is a well-studied but hotly contested medical intervention of enhanced infection control. Here, we aim to characterise the changes to the microbiome and antimicrobial resistance (AMR) gene profiles in critically ill children treated with SDD-enhanced infection control compared with conventional infection control.

Design
We conducted shotgun metagenomic microbiome and resistome analysis on serial oropharyngeal and faecal samples collected from critically ill, mechanically ventilated patients in a pilot multicentre cluster randomised trial of SDD. The microbiome and AMR profiles were compared for longitudinal and intergroup changes. Of consented patients, faecal microbiome baseline samples were obtained in 89 critically ill children. Additionally, samples collected during and after critical illness were collected in 17 children treated with SDD-enhanced infection control and 19 children who received standard care.

Results
SDD affected the alpha and beta diversity of critically ill children to a greater degree than standard care. At cessation of treatment, the microbiome of SDD patients was dominated by Actinomycetota, specifically Bifidobacterium, at the end of mechanical ventilation. Altered gut microbiota was evident in a subset of SDD-treated children who returned late longitudinal samples compared with children receiving standard care. Clinically relevant AMR gene burden was unaffected by the administration of SDD-enhanced infection control compared with standard care. SDD did not affect the composition of the oral microbiome compared with standard treatment.

Conclusion
Short interventions of SDD caused a shift in the microbiome but not of the AMR gene pool in critically ill children at the end mechanical ventilation, compared with standard antimicrobial therapy.

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Connecting inflammatory bowel and neurodegenerative diseases: microRNAs as a shared therapeutic intervention

We read with interest the recent article by Zhang et al that reported a higher risk of developing dementia in patients with inflammatory bowel disease (IBD), with the largest increase in Alzheimer’s disease (AD).1 These findings align with a growing body of evidence which links gut inflammation or leaky gut with neurodegeneration. Lee et al discussed the known shared pathophysiological links between IBD and Parkinson’s disease (PD), underscoring the importance of genetic overlap, microbiota gut-brain axis, autoimmunity, mitochondrial function and autophagy.2 We would like to highlight another less-explored biological connection: microRNAs (miRNAs). miRNAs are small non-coding RNAs, which regulate gene expression at the post-transcriptional level by silencing targeting mRNA(s). Intriguingly, miRNAs have been implicated in the pathogenesis of both IBD and neurodegenerative diseases (NDDs). miRNAs have emerged as important regulators of gut and blood–brain barrier (BBB) integrity.3 4 Complementing these findings,…

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