Nasal spray of virus enzymes for ear infections

Apr 27 2007

Parents might one day give their children a weekly treatment with a nasal spray of virus enzymes to prevent them from getting severe middle ear infections, based on results of a study done in mice by investigators from St. Jude and The Rockefeller University.

Such a treatment would avoid the use of antibiotics, thus eliminating the problem of antibiotic resistance. A report on this study appears in the March issue of the online journal PLoS Pathogens.

Middle ear infection, also called acute otitis media, is an inflammation of the middle ear space. About half of all children carry Streptococcus pneumoniae, the bacteria that cause the infection. These bacteria migrate from the nose and throat to the middle ear after an initial flu virus infection paves the way.

The investigators based their treatment on the ability of viruses called phages to break out of bacteria they infect by using a special enzyme to destroy the cell walls.

The success of the new treatment, which uses a phage enzyme called lysin to kill S. pneumonia , suggests that this strategy could significantly reduce the incidence of acute otitis media in the United States. More than 24 million cases are now diagnosed each year despite the use of vaccines against S. pneumoniae .

“Lysin also appears to hold promise for preventing the 'secondary' pneumonia caused when a person infected with S. pneumoniae is subsequently infected with the flu virus,” said the paper's first author, Jonathan McCullers, MD, Infectious Diseases.

Using mice developed at St. Jude, the investigators demonstrated that lysin can eliminate these bacteria from the ear. These mice represented the first such model in which acute otitis media develops in a similar way that it does in children, according to McCullers. The mice were treated by purified lysin that was prepared at The Rockefeller University.

“In the future, a weekly lysine spray during flu season to keep a person free of S. pneumoniae or after an infection with the flu virus might truly be a case in which an ounce of prevention is worth a pound of cure,” McCullers said.

Other St. Jude authors of this paper include Asa Karlström, PhD, and Amy R. Iverson, both of Infectious Diseases.