Initial or Mild Infections

1. The entire ear canal should be examined down to the tympanic membrane, samples taken for cytology and culture, and the ears thoroughly cleaned to remove debris and lipids. For mild cases, the ear canal can be gently cleaned with a ceruminolytic agent and loose cotton; more serious cases may require cleaning of the ear under anesthesia.
2. A cleaning and drying agent should be applied after cleansing the canals.
3. Topical treatment alternatives, based on cytology of exudate from ear canal: a) Use A Tris-EDTA product (TrizEDTA, DermaPet) applied 15 min prior to application of topical fluoroquinolone q 12 h. [Tris-EDTA extracts divalent cations from the cell envelope, causing release of phospholipids and cell fragility. Safe to use even if tympanic membrane is disrupted.] Place topical fluoroquinolone product in the ear canal and massage well. Products include: Baytril Otic (enrofloxacin/silver sulfadiazine, Bayer), or 1 part of injectable enrofloxacin at 22.7 mg/mL and add 4 parts of Synotic (fluocinolone acetonide in DMSO, Fort Dodge), 1% hydrocortisone, or saline; Ciloxan Ophthalmic Solution, Alcon, or Floxin Otic, Daiichi. b) Use solution of injectable enrofloxacin, tris EDTA, dexamethasone and/or DMSO in ear canals q 12 hr (12 mL of Tris EDTA, 100 mg enrofloxacin, 4-8 mg dexamethasone, 1-2 mL of medical grade DMSO). c) Use topical ear treatments that contain an aminoglycoside such as gentamycin, neomycin, amikacin, or tobramycin (Gentocin Otic or Otomax, Schering-Plough; Tresaderm, Merial; Tobrex or TobraDex, Alcon). d) Use topical polymyxin B, in combination with hydrocortisone and/or neomycin. [Compounded solutions or other formulations are considered extra-label treatments.]
4. Systemic treatment: As the likelihood of otitis media is high with Pseudomonas otitis externa, 4-16 weeks of systemic antibiotics, based on culture and sensitivity results are advocated by some experts. If no culture results are available, try enrofloxacin at 20 mg/kg/day or marbofloxacin at 5.5 mg/kg/day.
5. Include topical corticosteroids to decrease swelling and exudation in the ear canal.

For Chronic or Resistant Infections

1. Systemic antibiotics, based on culture and sensitivity results are advocated by some experts. For otitis media, systemic antibiotics may be needed for 12-16 weeks. Concurrent ear cleanings and use of topical antibiotics are essential.
2. If the above topical treatments have not worked, then try one of these preparations: a) Silver sulfadiazine 1 % (Silvadene, Monarch) cream (mix one part with 9 parts water and apply to ears). b) Injectable ticarcillin (add 30 mL sterile water to a 3 g bottle of ticarcillin; then take 1.8 mL of mixture and add 98.2 mL propylene glycol). Refrigerate and shake well before using; stable for at least 2 weeks.

Supportive and Preventive Therapy

1. Appropriate therapy is instituted for any underlying or accompanying systemic diseases.
2. For recurrent or resistant cases, consider inappropriate treatment or duration of treatment, underlying disease such as atopy or food allergy, otitis media, or ear canal conformation issues (stenotic canals, long floppy ears, masses, etc). All cases of Pseudomonas otitis externa should be rechecked periodically (10-14 days) to determine the response to treatment, and to watch for signs of recurrence. Therapy should be continued for 4 or more weeks to ensure the otitis does not immediately recur, or persists in chronic form.