DIAGNOSIS

The fragile skin of the external auditory canal is easily infected when disrupted by trauma or inflammation, permitting the normal ear flora (Staphylococcus spp., Streptococcus spp., diptheroids, and Pseudomonas aeruginosa) to invade the tissue. Acute uncomplicated otitis externa is diagnosed clinically. A history of local trauma, water exposure (“swimmer’s ear”), and travel to a warm, humid climate may be present.^1,2 Most patients will present with localized ear pain and itching. The pinna and tragus appears normal, but with manipulation elicits severe pain (a hallmark of this condition). The patient may not be able to lie down on that side or complains of even light wind eliciting pain. The ear canal itself is red and edematous with an exudate (Fig. 96-1); the tympanic membrane (TM) may be difficult to visualize. If the infection is due to a fungus (predominantly Aspergillus spp.), white or gray masses composed of hyphae may be seen in the canal. Local lymphadenopathy may be present.

Malignant or necrotizing otitis externa is most commonly caused by P. aeruginosa and is characterized by a severe cellulitis of the external canal with osteomyelitis of the underlying bone. Hospitalize these patients for IV antipseudomonal antibiotics and otolaryngology consultation. Imaging with MRI or CT is often necessary to define the extent of any bony and soft-tissue involvement.³ Otomycosis and necrotizing otitis externa are predominantly seen among diabetic or immunocompromised patients.¹

DIFFERENTIAL DIAGNOSIS

A furuncle (abscess) may develop at a hair follicle in the lateral canal. Depending on the degree of fluctuance, treat with a combination of antistaphylococcal topical or oral antibiotics and incision and drainage. Conditions affecting the skin of the ear, such as atopic dermatitis, seborrheic dermatitis, and contact dermatitis, may also lead to itching and inflammation of the external canal. Prolonged retained otic foreign bodies may create pain, edema, and debris in the external auditory canal mimicking AOE. Acute otitis media (AOM) with perforation and resultant debris and exudates may be mistaken for an external ear infection. The history (upper respiratory symptoms with fever versus swimming) as well as the time of year (winter cold and flu season versus summer humid months) may help with the diagnosis. Additionally, AOM generally will not cause pain with movement of the tragus, thus distinguishing the exudate of AOE with that of AOM with perforation.

MANAGEMENT

Use a combination of topical antimicrobial preparations (targeting P. aeruginosa) and external ear cleaning to treat uncomplicated AOE.⁴ Options include acetic acid, a combination of polymyxin B and neomycin, quinolones, and aminoglycosides. Antibiotic–steroid preparations may lead to faster and better cure rates (e.g., ciprofloxacin/dexamethasone drops).^5,6 Cleaning of the ear canal (with suctioning, irrigation, and dry swabbing) and/or application of an ear wick left in place for 2 days can help deliver the topical medications if significant edema and exudate exists. Use a topical antimicrobial suspension rather than a solution that may damage the middle ear if you suspect a perforated eardrum. Systemic antibiotics are not routinely recommended. Prevention strategies include reducing water exposure to the ear, using ear plugs, and vinegar/alcohol ear-drying solutions after water exposure.²

The middle ear is part of a continuous space behind the tympanic membrane that facilitates sound transfer to the inner ear structure and extends from the eustachian tube to the mastoid air cells. The eustachian tube functions to equilibrate middle ear pressure, clear the middle ear of secretions (via the action of ciliated epithelium), and protect the middle ear from the nasopharynx. Eustachian tubes in children are more horizontal in orientation than those of adults, possibly impeding drainage. Any alteration of function from obstruction, inflammation, or excessive compliance can lead to effusion and subsequent infection in the middle ear. Upper respiratory infections (URIs), allergic rhinitis, supine bottle-feeding, exposure to tobacco smoke, age younger than 2 years, and attendance at day care increase the risk of otitis media, whereas breast-feeding decreases its occurrence.⁷ Otitis media with effusion refers to a collection of serous fluid in the middle ear, which may commonly occur in a viral URI; AOM indicates superinfection with bacteria. Streptococcus pneumoniae (25%–50%), Haemophilus influenzae (15%–30%), and Moraxella catarrhalis (3%–20%) represent the major bacterial pathogens. The routine use of the heptavalent pneumococcal vaccine is changing the epidemiology of otitis media.⁷ A large number of H. influenzae and M. catarrhalis isolates produce β-lactamases, which affect therapeutic options; S. pneumoniae resistance is increasingly common (particularly penicillin resistance).

DIAGNOSIS

AOM is diagnosed clinically based on the rapid onset of signs and symptoms of middle ear inflammation and middle ear effusion. Symptoms include ear pain or fullness, fever, rhinorrhea, nasal congestion, and fussiness. Otorrhea may be present if the tympanic membrane has perforated. Middle ear effusion is highly suggested by a bulging tympanic membrane with decreased mobility confirmed by pneumatic otoscopy (Fig. 96-2). Redness and dullness of the eardrum can indicate infection but are less predictive,⁷ especially in a crying or febrile child whose tympanic membrane has normal mobility on pneumatic otoscopy. Routine tympanocentesis or cultures are not necessary for diagnosis.

DIFFERENTIAL DIAGNOSIS

While bullous myringitis is an infection of the tympanic membrane once associated with Mycoplasma pneumoniae, evidence suggests that it is mainly caused by the pathogens causing otitis media, particularly S. pneumoniae.⁸ It can occur alone or in combination with a middle ear infection and presents with bullae on the tympanic membrane. Effective visualization after suctioning can help distinguish otitis media with perforation from otitis externa. Instillation of anesthetic eardrops may help distinguish between crying due to otalgia from more serious conditions like meningitis.

COMPLICATIONS

Complications of AOM include tympanic perforation, cholesteatoma, facial paralysis, and labyrinthitis. Intracranial suppurative complications such as meningitis, brain abscess, encephalitis, and lateral sinus thrombosis, although rare, should be suspected in patients with worsening ear pain while taking antibiotics, persistent headache, intractable emesis, or behavioral changes. Children with acute mastoiditis (an infection of the mastoid bone) usually present with posterior auricular erythema, tenderness, and lateral displacement of the pinna. Obtain CT of the temporal bones if mastoiditis is suspected to determine the extent of infection and to detect sinus thrombosis or brain abscess (Fig. 96-3).⁹

MANAGEMENT

Most cases of AOM resolve without antibiotics.⁷ The overuse of antibiotics contributes to increasing bacterial resistance. The American Academy of Pediatrics (AAP) recommends a period of observation for 48 to 72 hours without antibiotics in select patients, such as patients older than 6 months with an uncertain diagnosis of otitis media and without severe symptoms, and those older than 2 years with otitis media but without severe symptoms (fever less than 40°C and mild otalgia).⁷ Delayed initiation of antibiotic therapy after an observation period does not lead to worse outcomes.¹⁰

In cases where antibiotics are indicated, use high-dose amoxicillin (80–90 mg/kg/d) as the first-line medication.⁷ For patients with non–type-1 penicillin allergy, use cefdinir (14 mg/kg/d in one or two divided doses), cefuroxime (30 mg/kg/d in two divided doses), or cefpodoxime (10 mg/kg/d). For patients with type 1 allergic reaction to penicillin (urticaria or anaphylaxis), use azithromycin (10 mg/kg on day 1, then 5 mg/kg on days 2–5 as a single dose), or clarithromycin (15 mg/kg in two divided doses). For treatment failure after 48 to 72 hours of amoxicillin or for severe otitis media as initial treatment, use high-dose amoxicillin-clavulanate (90 mg/kg/d in two divided doses) or a second- or third-generation cephalosporin as outlined above (see Chapter 99 for conjunctivitis otitis syndrome). A single dose of ceftriaxone (50 mg/kg) is equal in efficacy to 10 days of oral amoxicillin. Alternatively, deliver a series of three daily intramuscular doses of ceftriaxone patients who fail to improve after 48 to 72 hours. Refer patients with persistent treatment failures as well as those with recurrent middle ear infections to an otolaryngologist due to the potential chronic effects on hearing and development.

Mastoiditis is a serious complication of otitis media: treat aggressively. The most common causative agent is S. pneumoniae, with an increasing proportion of isolates showing resistance to penicillin.¹¹ Manage with IV antibiotics, with or without myringotomy, and in select cases, mastoidectomy to remove necrotic bone.¹²