Excessive Antibiotics May Harm Newborn Lungs

It has been well-established that antibiotics that treat infections can also disrupt the growth of gut bacteria in newborn babies. Findings from a new study published by Science Translational Medicine suggest that routine antibiotic use may actually lead to a longer-lasting effect in these children.

The investigators found that short-term disruption of gut bacteria increases the risk of developing pneumonia in infant mice. The mice were also observed to have an increased risk of pneumonia-related death.

Long-term disruptions in gut bacteria were observed to cause irreversible immune system damage. These findings may increase the conversation around antibiotic use, including prescribing the drugs to women before Cesarean sections, according to the study.

“It is time to begin pushing back on practices that were established decades ago, when our level of understanding was different,” said study lead author Hitesh Deshmukh, MD, PhD. “To prevent infection in one infant, we are exposing 200 infants to the unwanted effects of antibiotics. A more balanced, more nuanced approach is possible.”

In the United States, nearly every physician prescribes antibiotics prior to C-section delivery, and up to 30% of newborns in neonatal intensive care units (NICUs) also receive the drugs, according to the study.

These antibiotics prevent streptococcal infections, which are the leading cause of infection-related deaths in newborns. However, antibiotics are given as a precaution rather than a confirmed infection, which can lead to adverse events.

Antibiotics prescribed to newborns can kill both good and bad bacteria, despite the fact that good bacteria plays a vital role in creating a healthy immune system, according to the study.

The lungs and immune system of newborns are still being formed after birth, which leaves them vulnerable to changes.

In mice, the investigators found that a strong immune system depends on the molecular signals that occur as the body responds to normal bacteria located in the gut, according to the study. These signals communicate when the lungs should create immune cells, as well as how many to create, and where they will be deployed.

The study authors observed that commensal bacteria leads to the creation of group 3 innate lymphoid cells (ILC4), which then migrate to mucosal lining in the lungs, and create interleukin-22 (IL-22). This process initiates the immune response to an infection.

When antibiotics kill good bacteria, they inhibit the critical signaling response. This leaves the lungs weak, with less immune cells ready to respond to pathogens.

If the use of antibiotics is limited, a newborn would have time to replenish good gut bacteria, but this process can take months. Additionally, the investigators reported that even if the bacteria is replenished, it may not be a normal mix, according to the study.

At age 1, infants have completely formed immune systems, which suggests that any alterations sustained before that time may be permanent. This may explain why some people with no genetic risk factors develop asthma or lung diseases later in life, according to the authors.

While antibiotics play an integral role in treating infections, healthcare providers may re-think the drug’s preventive use in newborns.

However, there are current treatments to restore normal bacterial levels. In the study, the researchers found that the treatments restored immune system response to pneumonia in mice.

The investigators plan to conduct future studies to determine if these findings translate to humans, the study concluded.