Interpretations
Disruption of balance of vaginal microbiota causes invades of several
facultative or strict anaerobes, including Gardneralla vaginalis,
Mycoplasma hominis, Prevotella spp., Fusobacterium spp ., Ureoplasma
spp., and Porphyromonas spp. and replacement ofLactobacilli 26–28. Aligning with the
aforementioned results, we identified a significantly higher abundance
of Bacteroidetes in COVID-19 group. In particular, Prevotella
timonensis was only identified in women with COVID-19 (0.04%).
Likewise, Dialister propionicifaciens appeared in the COVID-19
group (0.02%). The SARS-CoV-2 infection triggers the production of
prostaglandins and pro-inflammatory mediators to confer ischemia
resulting in widespread tissues 29,30. Notably, we
determined an increase of anaerobic species such as Gardnerella
vaginalis , Anaerococcus tetradius , Fusobacterium
nucleatum , Prevotella timonensis abundance in women with severe
disease. Based on these results, we postulated that ischemia in
genito-urinary compartments could be a predisposing factor for
overgrowth of anaerobes in vaginal microbiota.
Pregnant women are more susceptible to SARS-CoV-2 infection due to
physiological, mechanical, and immunological changes during pregnancy2,31. Data supported that pregnancy is a risk factor
for severe disease related to COVID-19 4,32. Recently,
in a large population-based cohort study, fetal death and preterm birth
occurred more frequently in women with SARS-CoV-2 infection than
non-infected women (adjusted odds ratio (aOR), 2.21; 95% confidence
interval (CI), 1.58 – 3.11; P< 0.001 and OR, 2.17; 95% CI,
1.96 – 2.4; P<0.001, respectively) 1. In
the study, the prevalence of preterm birth (15.3%) was high, especially
in the severe COVID-19 (2 out of 3 preterm birth), as compared to the
prevalence reported before COVID-19 (9.6%) 33. Even
with the small sample size of our study, the rate of preterm birth
increased in women with severe COVID-19 disease than those with
asymptomatic or mild disease, aligning with a recent meta-analysis34. The abundance of Ureaplasma andMycoplasma species increased the risk of preterm delivery through
chorioamnionitis, salpingitis, bacterial vaginosis, and postpartum
endometritis 20,35. We found that Mycoplasma
hominis (8% vs. 0%; P=0.01) and Ureaplasma spp. (2.09% vs.
0.04%, p=0.001) showed significantly higher abundance in moderate or
severe cases compared to those of the healthy controls. Of note, the
abundance of Ureaplasma spp. was significantly higher in women
with moderate or severe disease than those of asymptomatic or mild
disease (p=0.005). We claim in light of these findings and previous
evidence from microbiota studies that the subsequent preterm birth in
women with severe disease could be a consequence of impaired vaginal
composition.