Indirect Effect of Azithromycin Use on the Intestinal Microbiome Diversity of Untreated Children: A Randomized Trial

Current understanding of antibiotic-associated dysbiosis and approaches for its management

Increased exposure to antibiotics during early childhood increases the risk of antibiotic-associated dysbiosis, which is associated with reduced diversity of gut microbial species and abundance of certain taxa, disruption of host immunity, and the emergence of antibiotic-resistant microbes. The disruption of gut microbiota and host immunity in early life is linked to the development of immune-related and metabolic disorders later in life. Antibiotic administration in populations predisposed to gut microbiota dysbiosis, such as newborns, obese children, and children with allergic rhinitis and recurrent infections; changes microbial composition and diversity; exacerbating dysbiosis and resulting in negative health outcomes. Antibiotic-associated diarrhea (AAD), Clostridiodes difficile-associated diarrhea (CDAD), and Helicobacter pylori infection are all short-term consequences of antibiotic treatment that persist from a few weeks to months. Changes in gut microbiota, which persist even 2 years after antibiotic exposure, and the development of obesity, allergies, and asthma are among the long-term consequences. Probiotic bacteria and dietary supplements can potentially prevent or reverse antibiotic-associated gut microbiota dysbiosis. Probiotics have been demonstrated in clinical studies to help prevent AAD and, to a lesser extent, CDAD, as well as to improve H pylori eradication rates. In the Indian setting, probiotics (Saccharomyces boulardii and Bacillus clausii) have been shown to reduce the duration and frequency of acute diarrhea in children. Antibiotics may exaggerate the consequences of gut microbiota dysbiosis in vulnerable populations already affected by the condition. Therefore, prudent use of antibiotics among neonates and young children is critical to prevent the detrimental effects on gut health.

Human microbiota research in Africa: a systematic review reveals gaps and priorities for future research

BACKGROUND

The role of the human microbiome in health and disease is an emerging and important area of research; however, there is a concern that African populations are under-represented in human microbiome studies. We, therefore, conducted a systematic survey of African human microbiome studies to provide an overview and identify research gaps. Our secondary objectives were: (i) to determine the number of peer-reviewed publications; (ii) to identify the extent to which the researches focused on diseases identified by the World Health Organization [WHO] State of Health in the African Region Report as being the leading causes of morbidity and mortality in 2018; (iii) to describe the extent and pattern of collaborations between researchers in Africa and the rest of the world; and (iv) to identify leadership and funders of the studies.

METHODOLOGY

We systematically searched Medline via PubMed, Scopus, CINAHL, Academic Search Premier, Africa-Wide Information through EBSCOhost, and Web of Science from inception through to 1st April 2020. We included studies that characterized samples from African populations using next-generation sequencing approaches. Two reviewers independently conducted the literature search, title and abstract, and full-text screening, as well as data extraction.

RESULTS

We included 168 studies out of 5515 records retrieved. Most studies were published in PLoS One (13%; 22/168), and samples were collected from 33 of the 54 African countries. The country where most studies were conducted was South Africa (27/168), followed by Kenya (23/168) and Uganda (18/168). 26.8% (45/168) focused on diseases of significant public health concern in Africa. Collaboration between scientists from the United States of America and Africa was most common (96/168). The first and/or last authors of 79.8% of studies were not affiliated with institutions in Africa. Major funders were the United States of America National Institutes of Health (45.2%; 76/168), Bill and Melinda Gates Foundation (17.8%; 30/168), and the European Union (11.9%; 20/168).

CONCLUSIONS

There are significant gaps in microbiome research in Africa, especially those focusing on diseases of public health importance. There is a need for local leadership, capacity building, intra-continental collaboration, and national government investment in microbiome research within Africa. Video Abstract.

Indirect effect of oral azithromycin on the gut resistome of untreated children: a randomized controlled trial

Background

Antibiotic use by one individual may affect selection for antimicrobial resistance in close contacts. Here we evaluated whether oral antibiotic treatment of one child within a household affected the gut resistome of an untreated cohabiting child.

Methods

Households with at least two children <5 y of age were randomized in a 1:1 fashion to a 5d course of azithromycin or placebo. To evaluate indirect effects of azithromycin treatment on the gut resistome, we randomly assigned one child in the house to azithromycin and one to placebo. In placebo households, each child received placebo. We performed DNA sequencing of rectal swabs collected 5 d after the last antibiotic dose. We estimated risk ratios for the presence of genetic resistance determinants at the class level using modified Poisson models for children in azithromycin households compared with placebo households and assessed the composition of the resistome using permutational analysis of variance (PERMANOVA).

Results

Of 58 children (n = 30 azithromycin households, n = 28 placebo households) with post-treatment rectal swabs, genetic resistance determinants were common but there was no significant difference at the class (p = 0.54 for macrolides) or gene (p = 0.94 for structure by PERMANOVA, p = 0.94 for diversity) level between untreated children in azithromycin households compared with placebo households.

Conclusions

The results are encouraging that one child's antibiotic use may not influence the resistome of another child.

Trial registration:ClinicalTrials.gov NCT03187834.

Projected impact and cost-effectiveness of community-based versus targeted azithromycin administration strategies for reducing child mortality in sub-Saharan Africa

BACKGROUND

Trials of mass drug administration (MDA) of azithromycin (AZM) report reductions in child mortality in sub-Saharan Africa (SSA). AZM targeted to high-risk children may preserve benefit while minimizing antibiotic exposure. We modeled the cost-effectiveness of MDA to children 1-59 months of age, MDA to children 1-5 months of age, AZM administered at hospital discharge, and the combination of MDA and post-discharge AZM.

METHODS AND FINDINGS

Models employed a payer perspective with a 1-year time horizon. Cost-effectiveness was presented as cost per DALY averted and death averted, with probabilistic sensitivity analyses. The model included parameters for macrolide resistance, adverse events, hospitalization, and mortality sourced from published data. Assuming a base-case 1.64% mortality risk among children 1-59 months old, 3.1% among children 1-5 months old, 4.4% mortality risk post-discharge, and 13.5% mortality reduction per trial data, post-discharge AZM would avert ~45,000 deaths, at a cost of $2.84/DALY (95% uncertainty interval [UI]: 1.71-5.57) averted. MDA to only children 1-5 months old would avert ~186,000 deaths at a cost of $4.89/DALY averted (95% UI: 2.88-11.42), MDA to all under-5 children would avert ~267,000 deaths a cost of $14.26/DALY averted (95% UI: 8.72-27.08). Cost-effectiveness decreased with presumed diminished efficacy due to macrolide resistance.

CONCLUSIONS

Targeting AZM to children at highest risk of death may be an antibiotic-sparing and cost-effective, or even cost-saving, strategy to reduce child mortality. However, targeted AZM averts fewer absolute deaths and may not reach all children who would benefit. Any AZM administration decision must consider implications for antibiotic resistance.