A. Introduction

1. Infection of the external auditory canal (~2.5cm long)
2. Similar to other skin and soft tissue infections
3. Classification of Infections
   1. Acute localized otitis externa
   2. Acute diffuse otitis externa
   3. Chronic otitis externa
   4. Malignant otitis externa

B. Normal Microbial Flora in External Auditory Canal

1. Staphylococcus epidermidis
2. Staphylococcus aureus
3. Diphtheroids
4. Anaerobes - especially Proprionobacterium acnes

C. Acute Localized Otitis Externa

1. Pustule or furuncle associated with hair follicles - due to Staphylococcus aureus
2. Erysipelas - group A Streptococci
3. Local Adenopathy is common
4. Treat with local heat and systemic antibiotics
   1. Antistaphylococcal pencillins: Dicloxacillin
   2. First generation cephalosporins: Cephalexin
   3. Quinolones

D. Acute Diffuse Otitis Externa

1. Also called Swimmer's Ear
2. Usually in hot, humid weather or following trauma
3. Ear pain and itching are main symptoms
4. May involve Gram Negative Rod including Pseudomonas aeruginosa
5. Local Treatment
   1. Gentle cleansing with hypertonic saline and alcohol-acetic acid mixture is helpful
   2. Antibiotic (Neomycin + Polymyxin) Drops with steroid added will decrease inflammation
   3. Ofloxacin (Floxin® otic) 5-10 drops bid for Staph. aureus or Pseudomonas
   4. Ciprofloxacin with hydrocortisone (Cipro® HC) bid drops may also be used
6. Systemic Antibiotics
   1. Oral ciprofloxacin may be effective against pseudomonas in mild or moderate cases
   2. Intravenous combination antipseudomonal drugs in moderate and severe infections

E. Chronic Otitis Externa

1. Due to irritation of drainage from the middle ear in patients with supperative otitis media
2. Itching may be severe
3. Very unusual causes of ear infection
   1. Tuberculosis
   2. Syphilis
   3. Leprosy
   4. Sarcoid

F. Malignant Otitis Externa [2]

1. Severe necrotizing infection with local tissue invasion
   1. Potentially life threatening
   2. Usually seen in diabetics
   3. Elderly and debilitated patients are also at risk
2. May extend to meninges or brain (hence the term "malignant")
3. Symptoms
   1. Severe, unrelenting pain and tenderness are common
   2. Otorrhea - pus drainage from canal
   3. Hearing loss
   4. Fever is uncommon
   5. Local symptoms may be unimpressive (minority of patients)
4. Delay in diagnosis of "malignant" otitis is common
   1. Delay in correct diagnosis can be life threatening
5. Treatment Overview
   1. Repeated debreadment
   2. Application of topical antipseudomonal or acetic acid drops
   3. Systemic antibiotic therapy with antipseudomonal coverage
6. Systemic Intravenous Antibiotics
   1. Double coverage for pseudomonas is essential
   2. An anti-pseudomonal penicillin is used
   3. An aminoglycoside is added (at least initially)
   4. Ciprofloxacin PO/IV may be an effective alternative
   5. Ofloxacin otic drops may also be used in addition to parenteral agents
   6. Duration is 4-6 weeks with careful assessment

G. Differential Diagnosis of Inflammatory Processes of Ear (Table 2 in Ref [3])

1. Infection - otitis externa
2. Trauma, especially with superinfection of ear (often Pseuomonas)
3. "Cauliflower Ear"
   1. Also called perichondrial hematoma
   2. Blood clot or other fluid collection under the perichondrium
   3. Common in wrestlers, rugby players, boxers, martial arts
   4. External portion of ear suffers trauma leading to the hematoma
   5. Fluid separates cartilage from perichondrium, which supplies nutrients to cartilage
   6. Cartilage will die if conditions remains, and ear can resemble a cauliflower
   7. May become infected
4. Insect bite
5. Sunburn
6. Frostbite
7. Relapsing Polychondritis

References

1. Bojrab DI, Bruderly T, Abdulrazzak Y. 1996. Otolaryngol Clin North Am. 29(5):761
2. Joshi N, Caputo GM, Weitekamp MR, Karchmer AW. 1999. NEJM. 341(25):1906
3. Butterton JR, Collier DS, Romero JM, Zembowicz A. 2007. NEJM. 356(19):1980 (Case Record)