Microbiome Resource Center
Microbiome Resource Center
September 23, 2019
2 min read

Long courses of antibiotics harm infant gut, promote resistance

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An NIH-funded study published in Nature Microbiology further highlighted the dangers of prolonged antibiotic use during infancy. Researchers found that infants who were heavily treated with antibiotics had reduced gut microbiota diversity and increased resistance genes to several antimicrobial agents.

“Infant gut microbiota assembly is accelerated during the first months of life, following inoculation with organisms from mothers and the environment, but stabilizes by approximately age 3 years,” Andrew J. Gasparrini, PhD, who was a graduate student at the Edison Family Center for Genome Sciences and Systems Biology at the Washington University School of Medicine in St. Louis, and colleagues wrote. “Treatment with antibiotics during the interval may disproportionately damage the host-microbiota ecosystem.”

Previous studies demonstrated that chronic metabolic and immune disorders, including allergies, psoriasis, adiposity, diabetes and inflammatory bowel disease, have been linked to changes in gut microbiota in infancy, the researchers noted.

Gasparrini and colleagues tested 437 fecal samples collected from 58 infants up to age 21 months using whole-metagenome shotgun sequencing. Most (n = 32) of the infants were born preterm with very low birth weight and received treatment in the NICU in St. Louis Children’s Hospital. The researchers also included nine late-preterm infants who received one antibiotic course for less than 1 week and 17 healthy term and late-preterm infants who received no antibiotics. Follow-up continued after discharge.

According to the researchers, preterm infants who received more than one course of antimicrobial therapy in the past month had significantly lower Shannon diversity compared with infants who were not treated with antibiotics during the study (P < .0001). Gasparrini and colleagues explained 57% of the differences in diversity were related to fixed effects like days of life and antibiotic treatments used.

Although resistance was observed against antibiotics typically used for neonates and infants, the researchers also observed resistance against antibiotics that are “rarely or never used in neonates.” These antibiotics included ciprofloxacin and chloramphenicol, as well as last-resort antibiotics for multidrug-resistant organisms like tigecycline and colistin.

“From a clinical standpoint, our findings emphasize a necessity for alternatives to broad-spectrum antimicrobial therapy for managing infection in the NICU,” the researchers wrote. “This should not only entail therapeutic approaches, such as narrow-spectrum antibiotics and probiotic therapies, but also improved accuracy and speed of diagnostics to reduce unnecessary courses of antibiotics.” – by Katherine Bortz

Disclosures: Gasparrini reports no relevant financial disclosures. Please see the full study for all other authors relevant financial disclosures.