COVID-19 Infection Alters the Microbiome: Elite Athletes and Sedentary Patients Have Similar Bacterial Flora

Abstract

Regular exercise can upgrade the efficiency of the immune system and beneficially alter the composition of the gastro-intestinal microbiome. We tested the hypothesis that active athletes have a more diverse microbiome than sedentary subjects, which could provide better protection against COVID-19 during infection. Twenty active competing athletes (CA) (16 male and 4 females of the national first and second leagues), aged 24.15 ± 4.7 years, and 20 sedentary subjects (SED) (15 male and 5 females), aged 27.75 ± 7.5 years, who had been diagnosed as positive for COVID-19 by a PCR test, served as subjects for the study. Fecal samples collected five to eight days after diagnosis and three weeks after a negative COVID-19 PCR test were used for microbiome analysis. Except for two individuals, all subjects reported very mild and/or mild symptoms of COVID-19 and stayed at home under quarantine. Significant differences were not found in the bacterial flora of trained and untrained subjects. On the other hand, during COVID-19 infection, at the phylum level, the relative abundance of Bacteroidetes was elevated during COVID-19 compared to the level measured three weeks after a negative PCR test (p < 0.05) when all subjects were included in the statistical analysis. Since it is known that Bacteroidetes can suppress toll-like receptor 4 and ACE2-dependent signaling, thus enhancing resistance against pro-inflammatory cytokines, it is suggested that Bacteroidetes provide protection against severe COVID-19 infection. There is no difference in the microbiome bacterial flora of trained and untrained subjects during and after a mild level of COVID-19 infection.

Acute and post-acute COVID-19 presentations in athletes: a systematic review and meta-analysis

“…Of the 43 studies and 11 518 infected athletes included in this systematic review, the median number (IQR) of participants per study was 26 (15–101). The included studies were conducted in Argentina,15 Australia,16 Brazil,1 17 Denmark,18 Finland,19 Germany,20–23 Hungary,8 24 25 Italy,9 26–31 Poland,14 Qatar,2 Russia,32 Serbia,33 Turkey,34 UK35 36 and USA 3 6 7 37–47. One study was a multicentre collaboration led by researchers in South Africa,48 and one study was conducted across different countries in Europe 49…”

“…Eleven (25%) studies included only male athletes,2 9 15 18 19 21 22 29 33 36 49 2 (5%) studies included only female athletes32 34 and 22 (51%) studies included both male and female athletes 1 3 6 8 14 16 24–28 35 37–39 41–44 46–48. Eight (19%) studies did not report data on sex 7 17 20 23 30 31 40 45.…”

“…Fourteen studies did not report the age of participants 2 7 9 18 22 23 31 32 36 37 40 44 45 49. Two studies included only amateur athletes,19 30 12 studies included only college/university athletes,3 6 37–40 42–47 1 study included both collegiate and amateur athletes27 and 23 studies included only professional/elite athletes 1 2 7–9 14–16 18 21 22 24–26 29 31–36 41 49. Three studies included both professional and non-professional athletes,23 28 48 and 1 study included professional, college and amateur athletes 17.…”

Gut microbiota and COVID-19: A systematic review

“…Five articles included in our study reported that gut microbiota composition can be a predictive factor in the severity of COVID-19 disease [24,27,61,71,78], and only one study reported no such association [67]. It has been shown that normal gut microbiota can decrease the severity of the COVID-19 course [20,24,42,43]. Babszky et al reported that Bacteroidetes spp.…”

“…Babszky et al reported that Bacteroidetes spp. in the feces has an anti-in ammatory effect and possess protective features against severe COVID-19 infection [43]. Similarly, Dereschuk et al reported that Less severe COVID infection can be associated with the presence of Bacillus subtilis spp.…”