Otitis externa is most commonly characterized by otalgia and otorrhea Necrotizing otitis externa should be considered in patients who are immunocompromised with severe disease Pseudomonas aeruginosa is the most common causative agent in both otitis externa and auricular perichondritis Otitis Externa Otitis externa (or external otitis) is inflammation of the external auditory canal It is particularly common in school-age children and those who participate in water sports Most children with otitis externa present with otalgia, otorrhea, and pruritus of the external ear or canal The diagnosis is made clinically based on symptoms, and a swollen, erythematous canal, often with exudate ( Fig 118.5 ) In severe or refractory cases, cultures of exudate from the canal specimens can be sent to confirm the infectious etiologic agent Care should be taken in patients with diabetes or immunosuppression to evaluate for malignant otitis externa, which is an osteomyelitis of adjacent bony structures Patients with malignant otitis externa are characterized by more severe pain and otorrhea, and may have cranial nerve palsies as well Imaging is essential for diagnosis Treatment of otitis externa involves debriding the ear canal, topical antibiotics and corticosteroid medications, and pain control P aeruginosa and S aureus are the most common causative agents, and antibiotic therapy should be tailored to those pathogens Topical fluoroquinolones such as ofloxacin and ciprofloxacin provide coverage against both pathogens, and are the first-line therapy in most patients If the external canal is occluded due to inflammatory swelling, an otic wick must be placed to allow medications to be drawn into the site of infection ( Fig 118.6 )