They found that almost all children with chronic otitis media (OM) had a type of bacterial infection known as a biofilm, which is resistant to antibiotic treatment.
Biofilms are antibiotic-resistant colonies of bacteria which are believed to attach to surfaces of the middle ear and form a slime-like barrier to protect themselves from eradication.
The researchers analysed biopsy specimens of middle-ear mucosa from 26 children aged from six months to 14 years who were undergoing tympanostomy tube placement for the treatment of otitis media with effusion, or recurrent otitis media.
They also analysed control samples taken from three children and five adults undergoing cochlear implantation, and looked for evidence of biofilms formed from the bacteria H influenzae, Streptococcus pneumoniae or Moraxella catarrhalis.
Biofilms were detected in 46 of 50 samples taken from the children with otitis media, but not in any of the eight samples taken from the control patients.
Lead researcher, Dr Garth Ehrlich, researcher at the Allegheny Singer Research Institute in Pittsburgh, said: 'In many cases, recurrent disease stems not from re-infection as was previously thought, but from a persistent biofilm.
'Given that bacteria living in biofilms are metabolically resistant to antibiotics, this study makes a clear case against the use of these drugs to treat children with chronic ear infections.
'It simply does not help the child and increases the risk of breeding more resistant strains of bacteria,' he said.