Antibiotics in Preterm Infants May Affect Their Healthy Gut Bacteria

Antibiotics in Preterm Infants May Affect Their Healthy Gut Bacteria

by Dr. Lakshmi Venkataraman on Sep 10 2019 6:14 PM
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  • Giving antibiotics to preterm infants can have potentially harmful longterm side effects by affecting the development of good bacteria in the gut, thereby increasing the risk of health problems and disease later in life
  • A single course of antibiotics in an initial couple of weeks of life can alter microbial flora by enabling harmful disease causing bacteria to gain a foothold in the gut. These bacteria remain for a very long time and have the ability to cause disease even at 40 years of age
  • Antibiotics have to be used very judiciously and antibiotic treatment must be initiated in newborns only when the benefits outweigh the risks, and even if antibiotics are started, the babies must be weaned off the antibiotics as soon as the infection has cleared
Routine administration of antibiotics to preterm infants to prevent infants can impair the development of healthy gut bacteria and promote the growth of unhealthy disease-causing bacteria which can be harmful even during adult life.
The study was carried out by scientists at the Washington University School of Medicine in St. Louis. The findings of the study appear in the journal Nature Microbiology and caution doctors against the indiscriminate use of antibiotics in preterm infants.

Effect of Antibiotics on Gut Microbial Flora

  • The team analyzed 437 fecal samples obtained from 58 babies, from newborn to 21 months of age
  • Forty-one of the 58 infants were premature by around 2 1/2 months, and the rest were full term
  • All of the preterm infants received antibiotics in the neonatal intensive care unit (NICU)
  • Nine had received just one course of antibiotics, and the other 32 had on an average been given eight courses of antibiotics receiving antibiotics for nearly half the duration of their stay in the NICU
  • The full-term babies did not receive any antibiotics
  • The team found that preterm babies heavily treated with antibiotics demonstrated significantly more drug-resistant bacteria in their gut at 21 months of age compared to preemies who received only a single course of antibiotics or full-term infants who received no antibiotics
  • Drug-resistant bacteria did not always cause immediate problems in the babies because they are rather harmless as long as they remain within the gut
  • However, gut bacteria sometimes escape from the intestine and reach the bloodstream, urinary tract or other parts of the body where they can cause severe infections that are resistant to antibiotics
  • The team also demonstrated that on culturing bacteria from fecal samples obtained eight to 10 months apart, the same drug-resistant strains were seen in older babies that were noted in their fecal samples earlier suggesting they persist
Gautam Dantas, PhD, a professor of pathology and immunology, biomedical engineering and molecular biology, and a senior author, said: "They weren't just similar bugs, they were the same bugs, as best we could tell. We had cleared an opening for these early invaders with antibiotics, and once they got in, they were not going to let anybody push them out. And while we didn't show that these specific bugs had caused disease in our kids, these are exactly the kind of bacteria that cause urinary tract and bloodstream infections and other problems. So you have a situation where potentially pathogenic microbes are getting established early in life and sticking around."
  • Further analysis showed that all of the babies developed diverse microbial flora in their gut by 21 months of age, which was a good thing since lack of diversity of gut flora is associated with several metabolic and immune diseases later in life
  • However, heavily treated preemies developed diverse gut flora much more slowly than mildly treated preemies and full-term infants who never received antibiotics
  • Also, the composition of gut microbial flora varied, with heavily treated preemies having lesser numbers of healthy groups of bacteria such as Bifidobacteriaceae and higher numbers of unhealthy bacteria such as Proteobacteria
The findings of the study suggest that use of antibiotics in preemies can cause alteration of gut microbial flora which persists and cause potentially longterm harmful effects and hence antibiotics must be used judiciously in newborns especially preterm babies.

Warner, who takes care of premature infants in the NICU at St. Louis Children's Hospital, said: "We're no longer saying, 'Let's just start them on antibiotics because it's better to be safe than sorry. Now we know there's a risk of selecting for organisms that can persist and create health risks later in childhood and in life. So we're being much more judicious about initiating antibiotic use."

In summary, the routine use of antibiotics in premature infants must be avoided as even a single course of antibiotics can have potentially harmful and longterm effects on the baby by altering the gut microbiome. Use antibiotics only if absolutely necessary and stop as soon as the infection clears.

  1. Use of antibiotics in preemies has lasting, potentially harmful effects - (