Oral Microbiome Linked to COVID-19 Diagnosis

By Marilynn Larkin

April 15, 2021

NEW YORK (Reuters Health) - Oral microbial markers may be a potential diagnostic tool for COVID-19, researchers suggest.

As reported in Gut, Dr. Lanjuan Li of Zhengzhou University in China and colleagues sequenced 392 tongue-coating samples, 172 fecal and 155 serum samples from Central and East China. They characterized the microbiome and lipid molecules, then constructed microbial classifiers in a discovery cohort and verified the diagnostic potential in 74 confirmed patients from East China and 37 suspected patients with IgG positivity.

Oral and fecal microbial diversity was significantly decreased in confirmed patients versus controls.

Specifically, butyric acid-producing bacteria were decreased and lipopolysaccharide-producing bacteria were increased in the oral cavity of confirmed patients.

The classifiers, based on eight optimal oral microbial markers and seven fecal microbial markers, achieved 87% diagnostic efficacy in the cross-regional cohort. Moreover, the classifiers were able to diagnose suspected patients with IgG antibody positivity as confirmed patients, and in this case, diagnostic efficacy reached 92% (98% of the fecal microbiome).

Further, 47 lipid molecules, including sphingomyelin (d40:4), sphingomyelin (d38:5) and monoglyceride (33:5), were depleted, and 122 lipid molecules, including phosphatidylcholine(36:4p), phosphatidylethanolamine (16:0p/20:5) and diglyceride (20:1/18:2), were enriched in recovered confirmed patients versus those who had not recovered.

Summing up, the authors state, "This study is the first to characterize the oral microbiome in COVID-19, and oral microbiomes and lipid alterations in recovered patients, to explore their correlations and to report the successful establishment and validation of a diagnostic model for COVID-19."

Dr. Mahmoud Ghannoum, director of the Center for Medical Mycology at Case Western Reserve University in Cleveland, Ohio, commented by email to Reuters Health, "The finding that there is an association between COVID-19 and the oral microbiome is quite promising. Apart from identifying the microorganisms that increase/decrease in COVID patients compared to healthy controls, the findings could have utility as an adjunct diagnostic tool for the disease."

"These data should be confirmed using other patient cohorts, with a focus on comparing the sensitivity and specificity of the conventional PCR test with that of the microbiome test alone and in combination," he said. "In other words, does using the microbiome as a diagnostic tool provide additional benefit to the myriad of available tests?"

"Microbiome dysbiosis occurs in the oral cavity of COVID patients and we should start thinking of new ways to rebalance the microbiome," he added. "Approaches that can increase the beneficial microbes and reduce pathogens (include) taking probiotics, prebiotics, and certain vitamins known to help in this regard - e.g., vitamins D3, A, B, and C. Adopting a healthy diet should be a core part of these strategies. The diet should nutritionally balanced, whole-food based, low-glycemic, rich in fiber and resistant starch, low in sugar, full of healthy mono- and polyunsaturated plant fats, and low in saturated fat and animal fat."

Dr. Miguel Freitas,VP of Scientific Affairs at Danone North America, also commented by email. "I am extremely encouraged by the findings, (which) have helped document the importance of microbial diversity to support the health of the microbiome," he said.

He also pointed to a recent study published in mBio suggesting that an imbalance of gut microbes may increase the chance of developing more severe COVID-19 symptoms, including the post-viral syndrome, 'long COVID' (https://bit.ly/2RqpNFU).

Like Dr. Ghannoum, he suggested helping to support the immune system with specific vitamins and probiotics. In addition, he noted, Danone has funded a study underway at Rutgers University in New Jersey exploring the link between the oral microbiome and COVID-19 severity in healthcare workers.

The study had no commercial funding, and the researchers report no conflicts of interest.

Dr. Li did not respond to requests for a comment.

SOURCE: https://bit.ly/2QsGbFG Gut, online March 31, 2021

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