The tightly regulated interplay between gut microbiota and host influences many physiological functions including immune homeostasis. A body of preclinical and clinical evidence shows that gut microbiota composition is transiently altered in the context of acute viral respiratory infections. In the case of Covid-19, studying the gut microbiota during infection is particularly important, given that SARS-CoV-2 can bind to ACE2 receptors in the gut, the virus is found in the intestine in up to 25% of patients, and the gut microbiota alterations associated with pulmonary and intestinal complications are likely to influence disease severity. This preclinical study is the first to investigate the role of SARS-CoV-2 infection in dynamic changes in the gut microbiota of monkeys.

The monkey: a good model for SARS-CoV-2 infection

The human data currently available on Covid-19 are abundant but do not allow the disease to be followed throughout its course, from pre-infection to post-resolution. The researchers used two species of monkeys (cynomolgus monkey and rhesus monkey) to fill in certain missing pieces of the infection puzzle. These non-human primates are a suitable model for the study of Covid-19, since SARS-CoV-2 infection led to virus replication in their upper and lower respiratory tracts, resulting in lung pathology and respiratory disease with no overt clinical symptoms. Two monkeys from each species were infected intranasally and intratracheally. Blood (to measure cytokine levels) and stool samples were collected 9 days prior to infection and at 0, 3, 5, 7, 10, 13, 20, and 26 days post-infection (dpi). Two of the monkeys had transient diarrhea at 4 dpi.

Covid-19: persistent dysbiosis even after resolution...

16S rRNA gene sequencing revealed significant changes in the composition of the monkeys’ gut microbiota, with a peak at 10-13 dpi. Some alterations in the microbiota persisted after SARS-CoV-2 was eliminated from the upper respiratory tract (virus undetectable in the nasopharynx and trachea at 20 dpi, but still detectable in the stool of two monkeys) and even at 26 dpi. A significant number of changes in the abundance of bacterial taxa were observed during infection, particularly at 13 dpi. In particular, the relative abundance of Acinetobacter and some genera of the Ruminococcaceae family was positively correlated with the presence of SARS-CoV-2 in the upper respiratory tract.

...and a gut microbiota with altered functional activity

A metabolomic approach was used to evaluate the functional consequences of the changes in the gut microbiota associated with the infection. The aim here was to quantify three of the most important categories of microbiota-derived metabolites: short-chain fatty acids (SCFAs), bile acids, and tryptophan metabolites. SCFA levels changed over the course of the infection, particularly between 2 and 13 dpi. Changes in several bile acids and tryptophan metabolites were also identified in infected animals. The relative abundance of several taxa known to be SCFA producers (mostly from the Ruminococcaceae family) was negatively correlated with certain systemic inflammatory markers, while the genus Streptococcus was strongly and positively correlated with the same markers. This study shows that experimental infection with SARS-CoV-2 in monkeys is associated with a disruption of the gut microbiota’s composition and functional activity. The persistence of dysbiosis after resolution of the infection may play a role in the long Covid-19 symptoms currently being reported in humans.

What do you brush away only for it to return immediately? Why dandruff, of course! Dandruff is a skin condition characterized by excessive flaking of the scalp, with or without itching, and involves a number of factors, including genetic susceptibility, the composition of the sebum and the scalp microbiota. A fungus called Malassezia is known to accelerate the development of dandruff and inflammation. Although effective against Malassezia, antifungals do not prevent the reappearance of dandruff after treatment is stopped. In Asian countries such as India, coconut oil is used to maintain scalp health, moisturize the skin and strengthen the skin’s barrier function. The researchers in this study compared the impact of coconut oil and a neutral shampoo on the scalp bacterial and fungal microbiota of 140 women with and without dandruff.

Dandruff: a specific fungus on the scalp?

The scalps of the women with dandruff had a much higher abundance of uncharacterized Malassezia species. Conversely, the fungus species M. globosa, was found in abundance on the scalps of the women with no dandruff or itching. Treatment with coconut oil brought the ratio of M. globosa to other groups of Malassezia in line with that of healthy scalps.

Coconut oil for the scalp’s engine?

Although no significant differences were observed between the bacterial microbiota of the healthy group and that of the dandruff group, both groups saw an increase in bacteria involved in the metabolism of biotin following coconut oil treatment. Biotin, a B vitamin, is essential for the maintenance of healthy skin and a healthy scalp, and is also known to reduce inflammation. Further studies are required to understand the underlying mechanisms, but for the researchers, the positive effect of coconut oil on the composition and function of the scalp microbiota is the first step towards the longer-term restoration of scalp health.

Irritable bowel syndrome in children & adolescents

This infographic explores irritable bowel syndrome (IBS) in children and adolescents, a common disorder of gut-brain interaction characterized by recurrent abdominal pain and changes in bowel habits.

It highlights the key symptoms, associated risk factors, and underlying biological mechanisms, including the role of gut microbiota imbalance (dysbiosis) in symptom development. Discover how the gut-brain axis contributes to IBS and explore practical strategies, ranging from diet and lifestyle to psychological support and targeted therapies, to help improve quality of life and support patient care.

What is bacterial vaginosis?

Bacterial vaginosis is the most common vaginal infection in women of reproductive age. It results from an imbalance in the vaginal microbiota, a delicate ecosystem normally dominated by protective lactobacilli.

This infographic explains what bacterial vaginosis is, how it differs from vulvovaginal candidiasis, its main risk factors and potential consequences, and how symptoms can be relieved. Understanding the role of the vaginal microbiota is key to better prevention and care.

Women’s microbiota: the missing piece in intimate health

This infographic explores the intimate microbiota — an essential yet often overlooked component of women’s health.
It highlights the distinct microbial ecosystems of the vulva, vagina, bladder, and perianal area, and explains how their balance protects against infections and supports overall well-being.

Discover the main factors that influence this delicate microbiota, common signs of imbalance, and practical tips to help patients maintain intimate health through proper hygiene.

Does gut microbiota influence satiety?

This infographic helps healthcare professionals explain to their patients how the gut microbiota influences satiety.

Discover how a balanced microbiota supports appetite regulation and overall health, and why maintaining its balance is essential for well-being.

From sampling to results: the microbiota analysis journey

Your patients often ask you about the purpose of microbiota analysis?

This infographic can be a first step in answering them. It outlines the key steps of microbiota analysis, from sample collection to final insights. Simplify complex processes and explore how microbiota data can impact health and personalized care.

Is healthy aging connected to the gut microbiota?

This infographic explores the link between gut microbiota and aging, highlighting how diet and lifestyle impact digestive health, immunity, and overall well-being in seniors.

Discover key factors influencing microbiota balance and strategies to promote healthy aging.

Gut-lung axis: how does gut microbiota protect against respiratory infections?

This infographic illustrates the gut-lung axis, detailing how gut microbiota modulates immune responses to safeguard against respiratory infections. It highlights the bidirectional communication between the gut and lungs.

Discover the mechanisms through which gut bacteria influence lung immunity and learn strategies to support this vital connection.

Gut-brain axis: gut microbiota as a mediator of stress response

This infographic explores the connection between gut microbiota and stress, highlighting how the gut-brain axis influences both mental and physical well-being.

It explains how stress impacts gut microbiota, the body's response mechanisms, and strategies to restore balance through lifestyle, diet, and psychobiotics.

Does vaginal microbiota play a role in infertility?

The vaginal microbiota plays a key role in reproductive health, yet its impact on fertility is often overlooked. An imbalance in vaginal flora can reduce pregnancy chances and affect assisted reproduction outcomes.

This infographic highlights the link between microbiota and fertility, emphasizing the importance of maintaining a balanced ecosystem through proper hygiene and patient education.

Gut brain axis: how your microbiota talks to your brain?

Your gut and brain are in constant communication, primarily through the gut microbiota. This connection plays a crucial role not only in digestion but also in various diseases, including neurological, psychiatric, and metabolic disorders.

Understanding this link could pave the way for new approaches to maintain our health.

The importance of the first 1000 days of life

This infographic highlights the critical importance of the first 1,000 days of an infant’s life, from conception to toddlerhood, in the development of gut microbiota and intestinal immunity. It explains how early factors, such as diet and environment, influence long-term health.

Learn how these foundational stages shape immune function and disease risk.

What is the Irritable Bowel Syndrome (IBS)?

This infographic explains Irritable Bowel Syndrome (IBS), a common functional bowel disorder characterized by recurrent abdominal pain and transit issues.

It explores how an imbalanced gut microbiota may contribute to IBS symptoms and highlights the role of diet, lifestyle, and psychological factors in managing the condition.

Discover strategies for improving quality of life and relieving IBS symptoms through microbiota management.

Do you know that an unbalanced microbiota is called a dysbiosis?

This infographic examines dysbiosis and how it disrupts thevarious microbiota of the human body, contributing to conditions like digestive, metabolic, and skin disorders, among others.

It outlines the causes of dysbiosis and offers strategies to restore balance through diet, lifestyle, and medical treatments.

5 things to know about the gut microbiota 

This infographic highlights 5 key facts about the gut microbiota, its essential role in digestion, immunity, and overall health. It explains how a balanced microbiota supports gut function and defends against pathogens, while imbalances can be linked to digestive, metabolic, and even neurodegenerative diseases.

Learn how lifestyle choices can influence microbiota health and reduce the risk of disease.

5 things to know about the vaginal microbiota

This infographic outlines 5 important things to know about the vaginal microbiota, including how it protects against infections and how hormonal changes affect its composition.

It also covers the consequences of dysbiosis and offers tips for maintaining a healthy balance through hygiene and lifestyle choices.

What you should know about antibiotics

This infographic covers key facts about antibiotics, explaining how they help fight infections while also affecting the balance of beneficial bacteria in the microbiota.

Overuse or misuse of antibiotics can lead to complications like antibiotic-associated diarrhea and contribute to the rise of antibiotic resistance.

What you need to know about the 6 microbiota of the human body

This infographic introduces the six microbiota of the human body, highlighting the unique functions and characteristics of each one, from the gut to the skin.

It explores how these microbiota are shaped by factors such as hormones, lifestyle, and delivery method, and how they contribute to overall health by protecting against infections and supporting immune function.

What are probiotics?

This infographic explains what are probiotics and how they help maintain a balanced microbiota, supporting overall health. It explores the types of beneficial microorganisms and the rigorous processes behind their production to ensure their effectiveness in promoting well-being.

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