Excessive Antibiotic Use in Newborns Can Permanently Damage Lungs’ Defenses

Published Feb. 8, 2017
Science Translational Medicine

Doctors have long understood that antibiotics that protect infants from infection also can disrupt the normal growth of gut bacteria. However, the consequences of routine antibiotic use may be deeper and longer lasting than expected.

A breakthrough study, led by Hitesh Deshmukh, MD, PhD, found that short-term disruption of gut bacteria makes infant mice more likely to develop pneumonia, and more likely to die from it. Longer term, continued disruptions appear to cause permanent damage to the immune system.

The team found that the presence of commensal bacteria triggers production of group 3 innate lymphoid cells (ILC3). These sentinel cells migrate to mucosal linings in the lungs, where they produce Interleukin-22 (IL-22). This signaling protein then helps activate immune response.

However, when antibiotics wipe out good bacteria, they cut off that important flow of signals. As a result, the lungs build weaker immune defenses.

These findings may spark a wider conversation about antibiotics use.

“It is time to begin pushing back on practices that were established decades ago, when our level of understanding was different,” Deshmukh says. “To prevent infection in one infant, we are exposing hundreds to the unwanted effects of antibiotics. A more balanced, more nuanced approach is possible.”

Nearly every C-section in the U.S. involves prescribing antibiotics to mothers shortly before delivery. Up to 30 percent of newborns in neonatal intensive care also receive antibiotics. While intended to prevent Group B streptococcal infections, in most cases the treatments are precautionary, Deshmukh says.

The good news: restoring commensal bacteria through fecal transplantation also restored resistance to pneumonia in mice, suggesting that fecal transplantation may become a valuable follow-up when antibiotics are necessary.