SARS-CoV-2会破坏肠道细菌的正常混合，增加感染其他病毒的风险

概要

一项新的研究发现，感染SARS-CoV-2会减少病人肠道中的细菌物种数量，而肠道内较少物种多样性为危险的微生物入侵人体创造了生存空间。研究人员表示目前不知道是冠状病毒感染破坏了肠道微生物组群，还是已经被削弱的肠道使人体更容易受到病毒的伤害。新研究似乎倾向于前者的解释。新的调查还显示，耐抗生素的物种可以逃逸到血液中，使病人面临更大的威胁生命的二次感染的风险。

这项调查受试者包括2020年因COVID-19住院的96名男性和女性。结果显示，大多数患者的肠道微生物组多样性较低，整整四分之一的患者肠道由单一类型的细菌主导。同时，几个已知包括抗生素耐药性物种的微生物种群有所增加，这可能是由于在新冠早期爆发的时候广泛使用抗生素的结果。同样在20%的病人中，这些在肠道中发现的抗生素耐药菌也被观察到迁移到了血液中。

研究结果表明，冠状病毒感染直接干扰了人体肠道中微生物的健康平衡，在此过程中进一步危及患者。新研究也首次表明，使用抗生素治疗冠状病毒疾病，会损害肠道微生物组。此外，研究还得出了肠道中的细菌最后还进入了病人的血液，使其遭受进一步感染的结论。

SARS-CoV-2 can disrupt normal mix of gut bacteria to increase risk for other infections

Infection with the pandemic virus, SARS-CoV-2, can reduce the number of bacterial species in a patient's gut, with the lesser diversity creating space for dangerous microbes to thrive, a new study finds.

The study builds on the realization that widespread use of antibiotics to fight infections with disease-causing bacteria in recent decades, by killing off species most vulnerable to available drugs, has left in place more species that are resistant to antibiotics. In addition, disruptions in gut bacterial ratios have previously been linked to more severe COVID-19.

However, researchers say, it has remained unclear until now which came first, the coronavirus infection disrupting the gut microbiome or an already weakened gut making the body more vulnerable to the virus. The new study appears to favor the former explanation. The new investigation also revealed that antibiotic-resistant species can escape into the bloodstream, putting patients at greater risk for life-threatening secondary infections.

Led by researchers at NYU Grossman School of Medicine, the investigation involved 96 men and women hospitalized with COVID-19 in 2020 in New York City and in New Haven, Conn. Results showed that the majority of patients had low gut microbiome diversity, with a full quarter dominated by a single type of bacteria. At the same time, populations of several microbes known to include antibiotic-resistant species increased, possible due to widespread antibiotic use early in the pandemic.

These antibiotic-resistant bacteria found in the gut were also observed to have migrated into the bloodstream in 20% of patients. The study authors note that further research is needed to uncover why this group was at higher risk for a secondary infection while others remained protected.

“Our findings suggest that coronavirus infection directly interferes with the healthy balance of microbes in the gut, further endangering patients in the process. Now that we have uncovered the source of this bacterial imbalance, physicians can better identify those coronavirus patients most at risk of a secondary bloodstream infection."

Ken Cadwell, PhD, study co-senior author and microbiologist

The new study is the first to show that the coronavirus infection alone, and not the initial use of antibiotics to treat the disease as others experts had thought, damages the gut microbiome, says Cadwell, also a professor in the Departments of Microbiology and Medicine at NYU Langone Health. He adds the study is also provides the first evidence that the very same bacteria in the gut are also entering the blood stream of patients, causing dangerous infections.

The report is publishing online Nov. 1 in the journal Nature Communications.

For the investigation, researchers first infected dozens of mice with the coronavirus and analyzed the makeup of bacterial species in their stool samples. This step allowed them to untangle whether the coronavirus could directly disrupt the microbiome independently of hospitalization and treatment.

Next, they collected stool samples and blood tests from COVID-19 patients at NYU Langone Health and Yale University hospitals to assess gut microbe composition and presence of secondary infection. If any bacteria group made up a majority of the bacteria living in the gut, they were considered dominant.

"Our results highlight how the gut microbiome and different parts of the body's immune system are closely interconnected," says study senior author Jonas Schluter, PhD, an assistant professor in the Department of Microbiology at NYU Langone and a member of its Institute for Systems Genetics. "An infection in one can lead to major disruptions in the other." Schluter cautions that since the patients received different kinds of treatments for their illness, the investigation could not entirely account for all factors that may have contributed to the disruption of their microbiome and worsen their disease.

According to Schluter, the study team next plans to examine why certain microbial species are more likely to escape the gut during COVID-19. The researchers say they also intend to explore how different microbes interact, which may contribute to this migration into the bloodstream.

Source:

News-Medical

Published on Novembre 1 2022

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