Bacterial sinusitis and otitis media following influenza virus infection in ferrets

Area of Science:

• Infectious Diseases
• Microbiology
• Virology

Background:

• Streptococcus pneumoniae is a primary cause of bacterial infections like pneumonia, otitis media, and sinusitis.
• Influenza virus infections often precede and facilitate these secondary bacterial infections.

Purpose of the Study:

• To investigate if different influenza virus strains influence the occurrence and nature of secondary pneumococcal infections.
• To explore the relationship between antecedent influenza virus strain and subsequent bacterial challenge outcomes.

Main Methods:

• Young ferrets were infected with various influenza virus subtypes (H3N2, H1N1, Influenza B).
• Following viral infection, ferrets were challenged with Streptococcus pneumoniae.
• Outcomes such as bacterial colonization, sinusitis, and otitis media were monitored.

Main Results:

• All tested influenza virus subtypes increased nasopharyngeal colonization by Streptococcus pneumoniae.
• Ferrets infected with H3N2 influenza A viruses showed a high incidence (9/10) of sinusitis or otitis media.
• In contrast, only 1 out of 11 ferrets infected with H1N1 influenza A or influenza B viruses developed these complications.

Conclusions:

• The strain of preceding influenza virus impacts the frequency and severity of secondary pneumococcal infections.
• H3N2 influenza A viruses appear to create a more permissive environment for severe bacterial complications.
• These findings may explain higher bacterial complication rates during H3N2-predominant flu seasons and highlight an animal model for studying viral-bacterial synergism.