Otowicks are used to treat otitis externa with significant ear canal oedema. This study investigates how well drops penetrate through to reach the deep canal and whether it is safe to leave otowicks in the canal for more than 2 days.

Sterile otowicks were inserted into mock ear canals and vertically over pseudomonas-seeded agar plates whilst gentamicin or ciprofloxacin drops were administered. The time taken for drops to penetrate through the otowick was recorded. Separately, pseudomonas-seeded otowicks were treated with saline or antibacterial drops. The penetrating drops were observed for bacterial growth on sterile agar.

It took six drops before penetration occurred for both antibiotics. When sterile saline drops were applied to bacterially contaminated otowicks, the penetrating drops displayed bacterial growth on agar, indicating that pseudomonas penetrated through the otowick. However, when antibiotic drops were applied, penetrating drops showed no bacterial growth on the corresponding agar plate.

Bacteria can penetrate otowicks but this is prevented by continuous application of antibacterial ear drops. Ear wicks need priming with six drops before starting a regimen, so that the initial dose is fully absorbed.