A new study indicates that the usual treatment for a common form of middle ear infection in children may not be effective.

Researchers from Allegheny General Hospital in Pittsburgh and the Medical College of Wisconsin in Milwaukee report today in the Journal of the American Medical Association that they have found direct evidence of bacterial biofilms on the middle ear tissue of children who suffer from chronic ear infections.

According to Garth Ehrlich of AGH, biofilms are antibiotic-resistant colonies of bacteria that attach to surfaces and form a slime-like barrier that protects bacteria.

"Nearly all of the children in our study who suffered from chronic otitis media tested positive for biofilms in the middle ear," Dr. Ehrlich said in a news release. "It appears that in many cases recurrent disease stems not from re-infection as was previously thought and which forms the basis for conventional treatment, but from a persistent biofilm."

The press release said the "discovery represents a landmark evolution in the medical community's understanding about a disease that afflicts millions of children worldwide each year."

Because bacteria living in biofilms are resistant to antibiotics, this study argues against the use of these drugs to treat children with chronic ear infections, researchers concluded. "It simply does not help the child and increases the risk of breeding more resistant strains of bacteria," Dr. Ehrlich said.

Although antibiotics have proven to be effective for children with acute middle ear infections where biofilms have not yet formed, those with the chronic disease typically benefit little from the drugs and more so from implanting small tubes in the eardrum to continuously drain fluid, researchers said.

More details in tomorrow's Pittsburgh Post-Gazette.