Bacteria-killing viruses fight ear infections too

An enzyme viruses use to punch holes in bacteria works to prevent ear infections in mice and might offer a safe way to prevent them in children, too, U.S. researchers said on Friday.

They said their surprisingly easy experiment might also be the first step toward preventing some deadly complications of influenza and other viral infections.

"This was an idea we had and it worked out right away. It was like magic," said Dr. Jonathan McCullers of St. Jude Children's Research Hospital in Memphis, Tennessee.

Years of testing must be done to make sure the treatment is safe, but it was 100 percent effective in mice, McCullers and colleagues report in Friday's issue of the Public Library of Science journal PLoS Pathogens.

As many as 80 percent of children in the United States have at least one ear infection in early childhood -- a condition known as acute otitis media.

It causes pain and temporary hearing loss and frantic parents often demand antibiotics from doctors. But antibiotics rarely work and studies suggest giving them to children for ear infections is helping drive the evolution of drug-resistant bacteria known as "superbugs."

Streptococcus pneumoniae is a common cause of these infections although viruses are also important, the researchers said. Often children are colonized with strep, meaning they carry the bacteria without symptoms, and then become ill after a viral infection like a cold or influenza.

"We had just discovered this particular strain (of S. pneumoniae) that causes otitis media really effectively. When we put it into mice it went right to their ears and caused ear infections right away," McCullers said in a telephone interview.

KILLER VIRUSES

Vincent Fischetti and colleagues at Rockefeller University in New York had been working with bacteriophages, a kind of virus that infects bacteria. He had one that killed Streptococcus pneumoniae very well and purified the enzyme that it uses to lyse, or punch a hole in, bacteria.

"Vince had this enzyme and he said, 'Will you test it?' and I did and it worked beautifully," McCullers said.

The enzyme, dripped into the noses of the mice, completely prevented ear infections in the mice.

Many researchers are finding that these bacteria-killing bacteriophages, or phages for short, can be manipulated to help medicine.

"These infectious viruses, when they want to leave the bacteria to go infect a lot of other bacteria and spread, they have developed these enzymes that punch a hole into the cell wall," McCullers said.

This kills the bacterium. The phages can be engineered in the lab to attack only specific kinds of bacteria, and are harmless to human cells.

"One of the applications we could imagine using is if you have kids in the wintertime that are prone to getting viruses and such, you could have nasal spray that you spray in the kid's nose once a week to just clear the bacteria out," McCullers said.

Or perhaps a spray could be used after a bout of influenza to prevent the secondary infections. This might be useful for elderly people, as seasonal flu kills 36,000 mostly elderly people every year in the United States.

"Most people don't die from the influenza, they die because of a bacterial infection after the flu," McCullers said.

But years of safety trials will have to be done before such a treatment could even be tested in children, he cautioned.