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Covid-19 could cause serious gut microbiota imbalance – Science et Avenir

Infection with the Covid-19 virus directly disrupts the gut microbiota, a study published in the journal Nature Communications concludes. As a result, in severe cases of Covid-19, flora imbalance can cause bacterial superinfections… coming from their own microbiota.

“Our data suggest that the dynamics in patients with Covid-19 may be similar to those in cancer patients. receiving bone marrow transplants“When it comes to the gut microbiota, the researchers say in the publication. Chemotherapy prior to this intervention really greatly disrupts the intestinal bacterial flora. “This is one of the rare cases where we can observe in some patients the predominance of only one or several types of bacteria in the microbiota,” said researcher Lucie Bernard. -Raichon, first author of this new work.

Infection with the Covid-19 virus alters the gut microbiota

Several studies have shown microbiota disturbances or dysbacteriosis in patients with Covid-19. But antibiotics given as a preventive measure in hospitalized patients to avoid nosocomial illness have a well-known effect on dysbiosis, which can exacerbate the effects of SARS-CoV-2. Thus, prior to this work, only two (in mice and hamsters) demonstrated that the virus itself caused this loss of microbial diversity. “But we were the first to detect an effect on epithelial cells (intestinal wall, editor’s note) and showed that antibiotics can worsen the situation,” says Lucie Bernard-Raichon.

In this new study, the researchers studied mice modified so that their cells possess human ACE2 receptors, the proteins that serve as the entry point for the Covid-19 virus. As the doses of the inoculated virus increased, the dysbacteriosis, determined in the faeces of mice, increased. “SARS-CoV-2 is not a virus capable of infecting bacteria. Thus, the modification of the composition of the microbiota that we observe during infection is caused indirectly, probably by an overactivation of the immune response,” explains Lucie Bernard-Raichon, this famous “cytokine storm.”

In addition, two very specific cell types have been affected by infection and increased dysbiosis in mice.

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