ear infections, which affect more than 85 percent of children under the age of
3, can be triggered by a viral infection in the nose rather than solely by a
bacterial infection, according to researchers at Wake Forest Baptist Medical
simultaneously infecting the nose with a flu virus and a bacterium that is one
of the leading causes of ear infections in children, the researchers found that
the flu virus inflamed the nasal tissue and significantly increased both the
number of bacteria and their propensity to travel through the Eustachian tube
and infect the middle ear.
study is published in the current online issue of the American Society for
Microbiology’s journal Infection and Immunity.
individual has bacteria in the nose that most of the time doesn’t cause
problems,” said the study’s lead author, W. Edward Swords, Ph.D., professor of
microbiology and immunology at Wake Forest Baptist. “However, under certain
conditions those bacteria can migrate to the middle ear and cause an ear
infection, and now we have a better understanding of how and why that happens.”
bacterium used in the animal study, Streptococcus pneumoniae, is known to exist
in the noses of children in two phases, one relatively invasive and the other
relatively benign. The more invasive phase is more frequently found in the
infected ears of children. However, the study indicated that the flu virus
promoted bacterial growth and ear infection regardless of which phase of the
bacterium was present in the nose.
findings suggest that a flu infection modifies the response of the immune
system to this particular bacterium, enabling even the type that has previously
been considered benign to infect the middle ear,” Swords said.
in Swords’ laboratory is sponsored by NIH Institute of Deafness and Other
Communication Disorders grant R01 DC10051 and AstraZeneca.
of the study are John T. Wren, B.S., Lance A. Blevins, B.S., Bing Pang, Ph.D.,
Lauren B. King, Ph.D., Antonia C. Perez, Ph.D., Kyle A. Murrah, Ph.D., Jennifer
L. Reimche, B.S., and Martha A. Alexander-Miller, Ph.D., all of Wake Forest