Bacterial resistance is likely of far less concern with topical
antimicrobials because the high local concentration of drug in
the ear canal will generally eradicate all susceptible organisms
plus those resistant to systemically administered antibiotics
(which only achieve concentrations at the site of infection several
magnitudes lower than when topically administered).5
The efficacy of topical therapy against resistant organisms is
of increasing importance given the rising incidence of drugresistant
Staphylococcus and community-acquired strains of
Pseudomonas.17