They have to be forcefully placed into the external canal and then will wick the eardrops into the canal. Garden variety, run of the mill, otitis externa is easily treated with Domboro otic or Vosol otic. If there appears to be a more advanced infection, particularly with a more significant bacterial component, polymyxin otics are popular and contain antibiotics and steroids. An occasional patient develops an allergic reaction to the polymyxins. If the antibacterial properties wish to be continued, Gentamicin or Tobramycin ophthalmic can be safely administered to the external ear canal and have come popular as otic medicaments.
Diabetics are at risk for developing a Pseudomonas osteomyelitis of the temporal bone.
This looks like otitis externa. The pain is greater and the disease is more severe. This is a fatal disease unless promptly diagnosed and aggressively treated. Oral antibiotics are never given for otitis externa. For such to be effective, they would need to cover Pseudomonas.