Who are the microbes that hide in the back of our noses?

Oeiras, 28 December 2023

Specific bacteria, smoking habits, and contact with children affect the composition of our upper respiratory tract’s microbiota, ITQB NOVA researchers reveal. In the long-run, the study, published in the scientific journal Microbiome, could help prevent diseases such as pneumonia and bacteremia.

Just like our gut, the upper part of our respiratory system (i.e. the nasopharynx, located right behind the nasal cavity, and oropharynx, at the back of the mouth) is colonized with bacteria, some helpful and others not so much. But there is still a lot that we don’t know about the bacteria that live in this particular part of our bodies, including who they are, what they do, and what influences them. 

Researchers from ITQB NOVA’s Molecular Microbiology of Human Pathogens lab, led by Raquel Sá-Leão, decided to dig deeper into the inside of the respiratory tract to answer these questions. For this, they studied samples from almost 60 healthy adults living in the Lisbon metropolitan area for six months.

One of the microorganisms commonly found in the back of the nose and throat is Streptococcus pneumoniae (also known as the pneumococcus), a significant cause of respiratory infections in young children and the elderly, which contributes to approximately 300 thousand child deaths each year. “We found that, when these bacteria were present in the nasopharynx, the community of microorganisms was more stable”, says Raquel Sá-Leão.
But there are other factors that influenced the number of harmful bacteria in these regions. “Smokers had more bacteria linked to gum diseases, while adults who spent more time around children had more bacteria associated with respiratory infections”, says Ana Cristina Paulo, co-first author of the paper and postdoc at ITQB NOVA. The type of bacteria found in healthy adults, especially in the nasopharynx and oropharynx, also varied with the season of the year and personal traits, such as age and sex. 

Now that researchers have an idea of the bacteria present in both the back of the nose and the throat, they can begin to understand how they interact with each other. “By delving into how the microbiota changes and interacts when pneumococcus is present, we could find better ways to prevent disease”, João Lança, a PhD student and co-first author of the paper, explains. With these new findings, researchers could explore the introduction of bacteria to prevent colonization by pneumococcus.

Image by Freepik.

ITQB NOVA researchers João Lança, Raquel Sá Leão, A. Cristina Paulo and Sónia T. Almeida

Original paper

Microbiome

The upper respiratory tract microbiota of healthy adults is affected by Streptococcus pneumoniae carriage, smoking habits, and contact with children.

A. Cristina Paulo, João Lança, Sónia T. Almeida, Markus Hilty and Raquel Sá Leão

DOI: https://doi.org/10.1186/s40168-023-01640-9

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