The Entero-Mammary Pathway and Perinatal Transmission of Gut Microbiota and SARS-CoV-2

Abstract

COVID-19 is a severe respiratory disease threatening pregnant women, which increases the possibility of adverse pregnancy outcomes. Several recent studies have demonstrated the ability of SARS-CoV-2 to infect the mother enterocytes, disturbing the gut microbiota diversity. The aim of this study was to characterize the entero-mammary microbiota of women in the presence of the virus during delivery. Fifty mother–neonate pairs were included in a transversal descriptive work. The presence of SARS-CoV-2 RNA was detected in nasopharyngeal, mother rectal swabs (MRS) and neonate rectal swabs (NRS) collected from the pairs, and human colostrum (HC) samples collected from mothers. The microbiota diversity was characterized by high-throughput DNA sequencing of V3-16S rRNA gene libraries prepared from HC, MRS, and NRS. Data were analyzed with QIIME2 and R. Our results indicate that several bacterial taxa are highly abundant in MRS positive for SARS-CoV-2 RNA. These bacteria mostly belong to the Firmicutes phylum; for instance, the families Bifidobacteriaceae, Oscillospiraceae, and Microbacteriaceae have been previously associated with anti-inflammatory effects, which could explain the capability of women to overcome the infection. All samples, both positive and negative for SARS-CoV-2, featured a high abundance of the Firmicutes phylum. Further data analysis showed that nearly 20% of the bacterial diversity found in HC was also identified in MRS. Spearman correlation analysis highlighted that some genera of the Proteobacteria and Actinobacteria phyla were negatively correlated with MRS and NRS (p < 0.005). This study provides new insights into the gut microbiota of pregnant women and their potential association with a better outcome during SARS-CoV-2 infection.

Genital Dysbiosis and Different Systemic Immune Responses Based on the Trimester of Pregnancy in SARS-CoV-2 Infection

“…In the rectal swabs, the Spread-CoV group showed an increase in proinflammatory bacteria such as Escherichia-Shigella which can weaken intestinal bacterial permeability [36]. On the contrary, the increase in Porphyromonas, which is a producer of butyric, isobutyric, isovaleric, acetic, and propionic acids, was reported in the Late-CoV, Early-CoV, and control groups [37,38]. The proinflammatory bacteria of the gut microbiomes from the Spread-CoV group, such as Bacteroides and Escherichia-Shigella [39], were also detected in the vagina.…”

Impact of SARS-CoV-2 on the microbiota of pregnant women and their infants

“…Low gut microbial diversity has been linked to negative health outcomes ( 48, 49 ). The fact that these changes were observed even if the infection was early in pregnancy, suggests the long-lasting effect of SARS-CoV-2 infection on gut microbial diversity ( 38 ). Similarly, other studies on non-pregnant Chinese population, COVID-19 is also associated with reduction in gut microbial richness ( 33 ) even lower than in H1N1 hospitalized patients ( 35 ), and also reported a long-lasting effect for at least 6 months post-infection ( 33 ).…”

“…Similarly, other studies on non-pregnant Chinese population, COVID-19 is also associated with reduction in gut microbial richness ( 33 ) even lower than in H1N1 hospitalized patients ( 35 ), and also reported a long-lasting effect for at least 6 months post-infection ( 33 ). Yet, a recent study including pregnant women from Mexico whose stool samples tested positive for SARS-CoV-2, despite of being asymptomatic or negative on nasopharyngeal swabs, suggesting earlier infection, do not report statistical differences in gut microbiota alpha diversity but showed differences in the gut microbiota composition and in specific taxa ( 38 ). Differences in results, might be due to the presence of SARS-CoV-2 in the gut - we did not assess SARS-CoV-2 in stools; or to geographical differences in the microbiota that could result in a varying response to the viral infection.…”

“…Most studies exploring the impact of SARS-CoV-2 infection on the microbiota have focused on the lung (32), gut (33)(34)(35), and nasopharyngeal mucosa (36) in non-pregnant adults. Two studies to our knowledge, have characterized the gut and nasopharyngeal microbiotas at the time of delivery and post-partum colostrum of pregnant women with SARS-CoV-2 infection (37,38). The first study conducted in Spain, reports an increased abundance of Bacteroidales in the nasopharyngeal swabs of pregnant women with active SARS-CoV-2 infection compared to healthy controls.…”

Angiotensin Converting Enzyme 1 Polymorphisms and Lipid Profile in Mexican Patients With COVID-19

“…For COVID-19 detection, nasopharyngeal swab samples were kept in viral transport medium according to the technique reported by Juarez-Castelan et al (16). RNA extraction was performed in a Magna Pure 96 instrument (Roche Diagnostic Corporation, Indianapolis, IN, USA) employing the RNA pure LC lysis kit/RNA isolation kit-high performance (Roche Diagnostic Corporation).…”