Influenza, Pneumococcal Coinfection Increase Ear Infection Risk

Influenza boosts the ability of pneumococci to cause middle ear and throat infections.

In a study published in Infection and Immunity, researchers from the Department of Microbiology and Immunology at Wake Forest School of Medicine determined that influenza boosts the ability of pneumococci to cause middle ear and throat infections.

After infecting mice with either influenza alone, pneumococci alone, or both at once, the research team monitored for otitis media development. In doing so, they discovered that influenza enhanced how the bacterium Streptococcus pneumoniae colonize the nasopharynx, thus infecting the normally sterile middle ear.

“We learned that, once influenza virus is introduced, all of the ‘rules’ regarding phase variants are out the window,” said corresponding author W. Edward Swords, PhD, in a press release. “However, in the presence of influenza, opaque variants can readily colonize the nasopharynx, and transparent variants can persist in the ear. This indicates that the host environs are more permissive for infection by the entire bacterial population.”

Previous research has proven that influenza interferes with innate immunity in a way that permits pneumococci to flourish. In this study, that interference revealed itself as an increase inflammatory response at the mucosal surface in influenza-infected mice.

“As with most pneumococcal infections, it should be appreciated that localized nonlethal infections are much more common than the rapidly lethal presentations. For example, influenza is a contributing factor in…middle ear infections in children,” Dr. Swords continued. “If we can understand why and how viral infection causes bacteria to colonize privileged sites like the middle ear, we will better know what aspects of disease to focus on with preventive or therapeutic treatments.”