According to a new report to be published today (November 1) in the journal Nature Communications, the virus that triggers the COVID-19 pandemic has been shown to reduce the number of bacterial species in a person's gut. This reduced microbiome diversity creates room for the dangerous microbial to thrive.
This study builds on the understanding that in recent decades, antibiotic has been widely used to fight infections of pathogenic bacteria, killing the species most susceptible to existing drugs, leaving behind more species that are resistant to antibiotics. In addition, the destruction of the proportion of gut bacteria was previously associated with more severe COVID-19.
However, according to the researchers, it is still unclear which one will come first. Is coronavirus infection destroying the intestinal microbiome, or is the already weakened intestine making the body more susceptible to the virus? New research seems to tend to the former explanation. New investigations also show that antibiotic-resistant species can escape into the blood, putting patients at greater risk of life-threatening secondary infection with .
This survey involved 96 men and women hospitalized for COVID-19 in New York City and New Haven, Connecticut in 2020 and was led by researchers at the Grossman School of Medicine at New York University. The results showed that most patients had a lower diversity in the gut microbiome, with a full quarter of patients dominated by a single type of bacteria. Meanwhile, several microbial populations known to include antibiotic-resistant species have increased, possibly due to the widespread use of antibiotics in the early stages of the pandemic.
In 20% of patients, these antibiotic-resistant bacteria found in the intestine were also observed to migrate into the blood. The study authors point out that further research is needed to reveal why this group has a higher risk of secondary infection, while others are still protected.
"Our results show that coronavirus infection directly interferes with the healthy balance of microorganisms in the gut, further endangering patients in the process," said study co-author Dr. Ken Cadwell, a microbiologist and co-author of the study. "Now that we have discovered the source of this bacterial imbalance, doctors can better identify those coronavirus patients who are most likely to develop secondary blood flow infections, and our results highlight how different parts of the gut microbiome and the body's immune system are closely linked. Infection in one aspect can lead to major damage in another."
New research shows for the first time that coronavirus infection itself brings these changes, rather than initially using antibiotics to treat the disease, as other experts believe, to damage the gut microbiome. Cadwell is a professor in the Department of Microbiology and Medicine at the Langone School of Health, NYU. He added that the study also provides the first evidence that bacteria in the gut also enter the patient's blood, causing a dangerous infection.
In the investigation, the researchers first infected dozens of mice with coronavirus and analyzed the composition of bacterial species in their fecal samples. This step allows them to unravel the question of whether the coronavirus can directly destroy the microbiome independently of hospitalization and treatment.
Next, they collected fecal samples and blood tests from COVID-19 patients at NYU Langone Hospital and Yale University Hospital to assess the gut microbial composition and the presence of secondary infections. If any bacterial population accounts for the majority of the bacteria that live in the gut, they are considered dominant.
"Our results highlight how different parts of the gut microbiome and the body's immune system are closely linked," said senior author Jonas Schluter, Ph.D., an assistant professor in the Department of Microbiology at New York University at Langone and a member of the Institute of Systems Genetics. "Infection in one person can lead to significant damage to another person." Since these patients were treated with different types of diseases, the survey cannot fully account for all the factors that could cause their microbiome to be destroyed and worsen their disease.
According to Schluter, the team plans to study why certain microbial species are more likely to escape from the gut during COVID-19.The researchers said they also intend to explore how different microorganisms interact, which may help this migration into the bloodstream.
