New Research Provides Insight on the Gut Microbiome's Role in Fighting Off Infection

Overuse of antibiotics not only leads to resistance, but may reduce variety of microbes in the gut and affect the immune system’s ability to fight off disease. Research into the role of the gut’s microbiome in infection found that antibiotic use made neutrophils less effective at fighting infections, and may lead to potential treatments or vaccinations.

A study recently published in PLOS Pathogens investigated the gut microbiome’s role in amebic colitis—a parasitic infection also known as amebiasis that is prevalent in developing countries and can often be deadly—by analyzing the stool samples of children in Dhaka and Bangladesh.

After discovering that children with more severe infections had less diversity in the gut microbiome, the researchers used lab mice to further explore how the natural intestinal flora affects the infection and potentially heightens the disease.

“Neutrophils play an important role as a first-line ‘innate immune response’ when foreign pathogens invade,” researcher Koji Watanabe, PhD, said in a statement. “We found that antibiotic disruption of the natural microbes in the gut prevented this from happening properly, leaving the gut susceptible to severe infection.”

The researchers found that with the use of antibiotics, neutrophils’ activity reduced and white blood cells were blocked from responding when necessary—ultimately resulting in an insufficiently protected gut. The antibiotic’s disruption of the gut also compromised the intestinal barrier that is meant to protect against diseases.

“I think the take-home is that this is another important reason not to use antibiotics unless they are clearly needed,” said researcher Bill Petri, MD, PhD, the chief of UVA’s Division of Infectious Diseases. “Unwise use of antibiotics not only increases the risk of multi-drug resistant bacteria and the risk of C. difficile infection but also impairs white blood cell function.”

The evidence of this study demonstrating the harms of antibiotic treatment and overall importance of the microbiome’s role could prove an important step in developing a vaccine for amebiasis. Although, the researchers noted the need for additional studies to assess the effects of antibiotic use for amebic colitis in a human cohort.

“Demonstration that antibiotics can impair neutrophil chemotaxis to a site of infection may be of broader importance than just amebiasis for the insight that it provides into gut microbiome regulation of the immune system,” the study concluded.