Extended effect of short-course azithromycin for the treatment of diarrhoea in children on antimicrobial resistance in nasopharyngeal and intestinal bacteria: Study Protocol for the antimicrobial resistance sub-study of the multicountry AntiBiotics for Children with Diarrhea (ABCD) trial.

Antimicrobial resistance (AMR) is a major public health challenge worldwide, threatening the important gains that have been made in reducing mortality due to infectious diseases. Despite current World Health Organization guidelines restricting antibiotics to a small subset of children with dysentery or suspected cholera, many children with diarrhea continue to be treated with antibiotics. We aim to determine the impact of a 3-day course of azithromycin on the risk of AMR at 90 and 180 days after treatment, among a subset of children and their household contacts enrolled into a multi-country, randomized, double-blind, placebo-controlled clinical trial of azithromycin children under 2 years with diarrhea in low income settings, Methods and analysis The AntiBiotics for Children with Diarrhea (ABCD) trial is testing the efficacy of a 3-day course of azithromycin, compared to placebo, in reducing mortality and linear growth faltering in the subsequent 6 months among 11,500 children aged 2-23 months of age across multiple sites in Bangladesh, India, Kenya Malawi, Mali, Pakistan and Tanzania with diarrhea and one or more of the following; dehydration, severe stunting, or moderate wasting (https://clinicaltrials.gov/ct2/show/NCT03130114). A sub-set of enrolled children are randomly selected to participate in a sub-study of AMR. A fecal sample (stool or rectal swab) will be collected at baseline from all enrolled children. A fecal sample and a nasopharyngeal (NP) swab will be collected at day 90 and 180 after enrolment from participating children and a close household child contact. Escherichia coli and Streptococcus pneumoniae will be isolated and Minimum Inhibitory Concentration for azithromycin and other commonly used antibiotics will be determined and compared between trial arms. Ethics and dissemination This study was reviewed by an independent ethical review committee. Dissemination of results is planned to local and international policy makers and the public.