Gut Microbiome among Children with Uncomplicated Severe Acute Malnutrition in a Randomized Controlled Trial of Azithromycin versus Amoxicillin

Antibiotics are routinely used as part of the management of severe acute malnutrition and are known to reduce gut microbial diversity in non-malnourished children. We evaluated gut microbiomes in children participating in a randomized controlled trial (RCT) of azithromycin versus amoxicillin for severe acute malnutrition. Three hundred one children aged 6 to 59 months with uncomplicated severe acute malnutrition (mid-upper arm circumference < 11.5 cm and/or weight-for-height Z-score <-3 without clinical complications) were enrolled in a 1:1 RCT of single-dose azithro-mycin versus a 7-day course of amoxicillin (standard of care). Of these, 109 children were randomly selected for micro-biome evaluation at baseline and 8 weeks. Rectal swabs were processed with metagenomic DNA sequencing. We compared alpha diversity (inverse Simpson's index) at 8 weeks and evaluated relative abundance of microbial taxa using DESeq2. Of 109 children enrolled in the microbiome study, 95 were followed at 8 weeks. We found no evidence of a dif-ference in alpha diversity between the azithromycin and amoxicillin groups at 8 weeks controlling for baseline diversity (mean difference-0.6, 95% CI-1.8 to 0.6, P = 0.30). Gut microbiomes did not diversify during the study. Differentially abundant genera at the P < 0.01 level included Salmonella spp. and Shigella spp., both of which were overabundant in the azithromycin compared with amoxicillin groups. We found no evidence to support an overall difference in gut micro-biome diversity between azithromycin and amoxicillin among children with uncomplicated severe acute malnutrition, but potentially pathogenic bacteria that can cause invasive diarrhea were more common in the azithromycin group. Trial Registration: ClinicalTrials.gov NCT03568643.