• Duration of respiratory infections and specific nose bacteria
• Conclusions

  • What is already known on this topic
    Viral infections and the colonization of the airways by bacteria such as Moraxella catarrhalis, Haemophilus influenzae and Streptococcus pneumoniae have been associated with a higher risk of developing childhood asthma. But little is known about the interplay between viruses, bacteria and host.

  • What this research adds
    The researchers analyzed the nose microbiota of 167 babies at the onset and three weeks after their first airways infection. Babies who had more variety in the types of bacteria living in their noses tended to recover more quickly compared to those who had less variety and more bacteria from the Moraxellaceae or Streptococcaceae family.

  • Conclusions
    The results suggest that nose-dwelling bacteria may influence the duration of respiratory infections. The study could also offer clues as to why some babies recover quickly from coughs and colds, while others don’t.


Specific nose-dwelling bacteria are linked to the duration of babies’ cold and coughs, researchers report in the journal ERJ Open Research. The study was led by Roland Neumann of the University of Basel and Markus Hilty of the University of Bern, both in Switzerland.

Chronic respiratory diseases such as asthma have been associated with viral infections of the airways as well as the presence of bacteria such as Moraxella catarrhalis, Haemophilus influenzae and Streptococcus pneumoniae. But how the interaction between viruses, bacteria and host is linked to respiratory diseases is not completely understood.

To start addressing this question, the researchers looked at the nose microbiota of 167 healthy babies who showed symptoms of their first respiratory infection at the onset of the infection and three weeks after.

The duration of respiratory infections is associated with specific nose bacteria

Parents taking part in the study were asked to contact the researchers as soon as their babies showed symptoms of their first respiratory infection, which included more than two consecutive days of cough and runny nose or signs of an ear infection or sore throat.

At that point, the researchers took swabs from the noses of babies and tested the swabs for the presence of bacteria and respiratory viruses such as the common cold. The team took and analyzed swabs again three weeks later.

At the onset of the infection, the researchers were able to divide the babies in 5 groups according to the make-up of their nose microbiota:

  • Group A1 (dominated by bacteria of the Moraxellaceae family)
  • Group A2 (dominated by bacteria of the Moraxellaceae and Streptococcaceae families)
  • Group A3 (dominated by bacteria of the Streptococcaceae family)
  • Group A4 (dominated by other bacterial families, including Neisseriaceae, Prevotellaceae, and Flavobacteriaceae)
  • Group A5(dominated by bacteria of the Pasteurellaceae family)

Three weeks after the infection, the babies could be divided in 3 groups according to their nose microbiota composition:

  • Group B1 (dominated by bacteria of the Moraxellaceae family)
  • Group B2 (dominated by other bacterial families, including Neisseriaceae, Prevotellaceae, and Flavobacteriaceae)
  • Group B3 (dominated by bacteria of the Streptococcaceae family)

The babies’ symptoms lasted about two weeks in average. Babies whose symptoms lasted three weeks or longer showed less variety in the types of nose-dwelling bacteria compared with babies who recovered in less than three weeks.

Babies who recovered slowly also tended to have a nose microbiota dominated by bacteria from the Moraxellaceae or Streptococcaceae family (Groups B1 and B3).

The researchers also analyzed the presence of respiratory viruses in the swabs but found no clear link between the type of viruses and the duration of respiratory symptoms.

Conclusions

In conclusion, babies who recovered slowly from their first respiratory infection had a different nose microbiota compared to babies who recovered more quickly, which suggests that nose-dwelling bacteria may influence the duration of respiratory infections. However, more research is needed to address how the nose microbiota is linked to inflammation and chronic respiratory diseases.