Application of antibiotics before 3 years of age increases the risk of childhood overweight and obesity

Single-dose azithromycin for infant growth in Burkina Faso: Prespecified secondary anthropometric outcomes from a randomized controlled trial

BACKGROUND

Antibiotic use during early infancy has been linked to childhood obesity in high-income countries. We evaluated whether a single oral dose of azithromycin administered during infant-well visits led to changes in infant growth outcomes at 6 months of age in a setting with a high prevalence of undernutrition in rural Burkina Faso.

METHODS AND FINDINGS

Infants were enrolled from September 25, 2019, until October 22, 2022, in a randomized controlled trial designed to evaluate the efficacy of a single oral dose of azithromycin (20 mg/kg) compared to placebo when administered during well-child visits for prevention of infant mortality. The trial found no evidence of a difference in the primary endpoint. This paper presents prespecified secondary anthropometric endpoints including weight gain (g/day), height change (mm/day), weight-for-age Z-score (WAZ), weight-for-length Z-score (WLZ), length-for-age Z-score (LAZ), and mid-upper arm circumference (MUAC). Infants were eligible for the trial if they were between 5 and 12 weeks of age, able to orally feed, and their families were planning to remain in the study area for the duration of the study. Anthropometric measurements were collected at enrollment (5 to 12 weeks of age) and 6 months of age. Among 32,877 infants enrolled in the trial, 27,298 (83%) were followed and had valid anthropometric measurements at 6 months of age. We found no evidence of a difference in weight gain (mean difference 0.03 g/day, 95% confidence interval (CI) -0.12 to 0.18), height change (mean difference 0.004 mm/day, 95% CI -0.05 to 0.06), WAZ (mean difference -0.004 SD, 95% CI -0.03 to 0.02), WLZ (mean difference 0.001 SD, 95% CI -0.03 to 0.03), LAZ (mean difference -0.005 SD, 95% CI -0.03 to 0.02), or MUAC (mean difference 0.01 cm, 95% CI -0.01 to 0.04). The primary limitation of the trial was that measurements were only collected at enrollment and 6 months of age, precluding assessment of shorter-term or long-term changes in growth.

CONCLUSIONS

Single-dose azithromycin does not appear to affect weight and height outcomes when administered during early infancy.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03676764.

Neonatal Azithromycin Administration and Growth during Infancy: A Randomized Controlled Trial

Observational studies have linked early-life antibiotic exposure to increased risk of obesity in children in high income settings. We evaluated whether neonatal antibiotic exposure led to changes in infant growth at 6 months of age in Burkina Faso. Neonates aged 8 to 27 days of age who weighed at least 2,500 g at the time of enrollment were randomized in a 1:1 fashion to a single oral 20-mg/kg dose of azithromycin or equivalent volume of placebo from April 2019 through December 2020. Weight, length, and mid-upper-arm circumference (MUAC) were measured at baseline and 6 months of age. Growth outcomes, including weight gain in grams per day, length change in millimeters per day, and changes in weight-for-age Z-score (WAZ), weight-for-length Z-score (WLZ), length-for-age Z-score (LAZ), and MUAC were compared among neonates randomized to azithromycin compared with placebo. Among 21,832 neonates enrolled in the trial, median age at enrollment was 11 days, and 50% were female. We found no evidence of a difference in weight gain (mean difference -0.009 g/day, 95% confidence interval [CI]: -0.16 to 0.14, P = 0.90), length change (mean difference 0.003 mm/day, 95% CI: -0.002 to 0.007, P = 0.23), or WAZ (mean difference -0.005 SD, 95% CI: -0.03 to 0.02, P = 0.72), WLZ (mean difference -0.01 SD, 95% CI: -0.05 to 0.02, P = 0.39), LAZ (mean difference 0.01, 95% CI: -0.02 to 0.04, P = 0.47), or MUAC (mean difference 0.01 cm, 95% CI: -0.02 to 0.04, P = 0.49). These results do not suggest that azithromycin has growth-promoting properties in infants when administered during the neonatal period. Trial registration: ClinicalTrials.gov NCT03682653.

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.