Influenza A virus alters pneumococcal nasal colonization and middle ear infection independently of phase variation

Area of Science:

• Microbiology
• Infectious Diseases
• Otolaryngology

Background:

• Streptococcus pneumoniae (pneumococcus) is a common nasal colonizer and a leading cause of childhood otitis media.
• Pneumococcal phase variation impacts colonization and disease, influencing its transition to an otopathogen.
• Coinfection with influenza A virus is epidemiologically linked to pneumococcal spread from the nasopharynx to the middle ear.

Purpose of the Study:

• To investigate the impact of influenza virus coinfection on pneumococcal colonization and otitis media development.
• To determine if pneumococcal phase variation influences the exacerbation of otitis media during coinfection.
• To elucidate the synergistic relationship between pneumococcus and influenza virus in middle ear infections.

Main Methods:

• A mouse infection model was utilized to study coinfection with influenza virus and Streptococcus pneumoniae.
• Pneumococcal populations were enriched for opaque or transparent phase variants for comparative analysis.
• In vitro assays assessed biofilm viability and epithelial adherence of different pneumococcal phases.

Main Results:

• Coinfection with influenza virus enhanced both nasopharyngeal colonization and middle ear inflammation in mice.
• Influenza virus coinfection ameliorated the reduced nasopharyngeal colonization defect of opaque pneumococcal variants.
• Viral coinfection led to similar middle ear infection severity by both opaque and transparent pneumococcal variants.

Conclusions:

• Influenza A virus exacerbates experimental otitis media independently of pneumococcal phase variation.
• Despite differences in colonization ability, pneumococcal phase does not alter the severity of influenza-induced middle ear infections.
• These findings highlight a synergistic interaction between pneumococcus and influenza virus in the pathogenesis of otitis media.