Otitis Media

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ETIOLOGY

Otitis media (OM) is a suppurative infection of the middle ear cavity. Bacteria gain access to the middle ear when the normal patency of the eustachian tube is blocked by upper airway infection or hypertrophied adenoids. Air trapped in the middle ear is resorbed, creating negative pressure in this cavity and facilitating reflux of nasopharyngeal bacteria. Obstructed flow of secretions from the middle ear to the pharynx combined with bacterial reflux leads to infected middle ear effusion. Both bacteria and viruses can cause OM. The common bacterial pathogens are Streptococcus pneumoniae, nontypable Haemophilus influenzae, Moraxella catarrhalis, and, less frequently, group A streptococcus. S. pneumoniae that is relatively resistant to penicillin (minimal inhibitory concentration 0.1 to 1 μg/mL) or highly resistant to penicillin (minimal inhibitory concentration ≥2 μg/mL) is isolated with increasing frequency from young children, particularly those who attend day care or have received antibiotics recently. Viruses, including rhinoviruses, influenza, and respiratory syncytial virus, are recovered alone or as copathogens in 20% to 25% of patients.

EPIDEMIOLOGY

Diseases of the middle ear account for approximately one third of office visits to pediatricians. The peak incidence of acute OM is between 6 to 15 months of life. By the first birthday, 62% of children experience at least one episode. Few first episodes occur after 18 months of age. OM is more common in boys and in patients of lower socioeconomic status. There is increased incidence of OM in Native Americans and Alaskan Natives and in certain high-risk populations, such as children with human immunodeficiency virus (HIV), cleft palate, and trisomy 21. In most of the United States, OM is a seasonal disease with a distinct peak in January and February, which corresponds to the rhinovirus, respiratory syncytial virus, and influenza seasons. It is less common from July to September. The major risk factors for acute OM are young age, bottle-feeding as opposed to breastfeeding, drinking a bottle in bed, parental history of ear infection, presence of a sibling in the home (especially a sibling with a history of ear infection), sharing a room with a sibling, passive exposure to tobacco smoke, and increased exposure to infectious agents (day care).
As defined by the presence of six or more acute OM episodes in the first 6 years of life, at least 12% of children in the general population have recurrent OM and would be considered otitis-prone. Craniofacial anomalies and immunodeficiencies often are associated with recurrent OM; most children with recurrent acute OM are otherwise healthy.

CLINICAL MANIFESTATIONS

In infants, the most frequent symptoms of acute OM are nonspecific and include fever, irritability, and poor feeding. In older children and adolescents, acute OM usually is associated with fever and otalgia (acute ear pain). Acute OM also may present with otorrhea (ear drainage) after spontaneous rupture of the tympanic membrane. Signs of a common cold, which predisposes to acute OM, are often present (see Chapter 102). A bulging tympanic membrane, air fluid level, or visualization of purulent material by otoscopy are reliable signs of infection (Table 105-1).

LABORATORY AND IMAGING STUDIES

Table 105-1. Definition of Acute Otitis Media (AOM)
A diagnosis of AOM requires
History of acute onset of signs and symptoms
Presence of middle ear effusion
Signs and symptoms of middle ear inflammation
The definition of AOM includes all of the following:
Recent, usually abrupt, onset of signs and symptoms of middle ear inflammation and middle ear effusion
The presence of middle ear effusion that is indicated by any of the following:
Bulging of the tympanic membrane
Limited or absent mobility of the tympanic membrane
Air-fluid level behind the tympanic membrane
Otorrhea
Signs or symptoms of middle ear inflammation as indicated by either
Distinct erythema of the tympanic membrane or
Distinct otalgia (discomfort clearly referable to the ear that results in interference with or precludes normal activity or sleep)
Routine laboratory studies, including complete blood count and erythrocyte sedimentation rate, are not useful in the evaluation of OM. Tympanometry provides objective acoustic measurements of the tympanic membrane-middle ear system by reflection or absorption of sound energy from the external ear duct as pressure in the duct is varied. Measurements of the resulting tympanogram correlate well with the presence or absence of middle ear effusion.
Instruments using acoustic reflectometry are available for office and home use. Use of reflectometry as a screening test for acute OM should be followed by examination with pneumatic otoscopy when abnormal reflectometry is identified.
Bacteria recovered from the nasopharynx do not correlate with bacteria isolated by tympanocentesis. Tympanocentesis and middle ear exudate culture are not always necessary, but they are required for accurate identification of bacterial pathogens and may be useful in neonates, immunocompromised patients, and patients not responding to therapy

DIFFERENTIAL DIAGNOSIS

Examination of the ears is essential for diagnosis and should be part of the physical examination of any child with fever. The hallmark of OM is the presence of effusion in the middle ear cavity (see Table 105-1). The presence of an effusion does not define its nature or potentially infectious etiology, but it does define the need for appropriate diagnosis and therapy.
Pneumatic otoscopy, using an attachment to a hermetically sealed otoscope, allows evaluation of ventilation of the middle ear and is a standard for clinical diagnosis. The tympanic membrane of the normal, air-filled middle ear has much greater compliance than if the middle ear is fluid-filled. With acute OM, the tympanic membrane is characterized by hyperemia, or red color rather than the normal pearly gray color, but it can be pink, white, or yellow with a full to bulging position and with poor or absent mobility to negative and positive pressure. The light reflex is lost, and the middle ear structures are obscured and difficult to distinguish. A hole in the tympanic membrane or purulent drainage confirms perforation. Occasionally, bullae are present on the lateral aspect of the tympanic membrane, which characteristically are associated with severe ear pain.
The major difficulty is differentiation of acute OM from OM with effusion, which also is referred to as chronic OM. Acute OM is accompanied by signs of acute illness, such as fever, pain, and upper respiratory tract inflammation. OM with effusion is the presence of effusion without any of the other signs and symptoms.

TREATMENT

Recommendations for treatment are based on certainty of diagnosis and severity of illness. A certain diagnosis can be made if there is rapid onset, signs of middle ear effusion, and signs and symptoms of middle ear inflammation. The recommended first-line therapy for most children with a certain diagnosis of acute OM or those with an uncertain diagnosis but who are younger than 2 years of age or have fever greater than 39 ° C or otalgia is amoxicillin (80 to 90 mg/kg/day in two divided doses). Children with an uncertain diagnosis who are older than 2 years of age may be observed if appropriate follow-up can be arranged. Failure of initial therapy with amoxicillin at 3 days suggests infection with β-lactamase-producing H. influenzae or M. catarrhalis or resistant S. pneumoniae. Recommended next-step treatments include high-dose amoxicillin-clavulanate (amoxicillin 80 to 90 mg/kg/day), cefuroxime axetil, cefdinir, or ceftriaxone (50 mg/kg intramuscularly in daily doses for 1 to 3 days). Intramuscular ceftriaxone is especially appropriate for children younger than 3 years of age with vomiting that precludes oral treatment. Tympanocentesis may be required for patients who are difficult to treat or who do not respond to therapy. Acetaminophen and ibuprofen are recommended for fever. Decongestants or antihistamines are not effective.

COMPLICATIONS AND PROGNOSIS

The complications of OM are chronic effusion, hearing loss, cholesteatoma (masslike keratinized epithelial growth), petrositis, intracranial extension (brain abscess, subdural empyema, or venous thrombosis), and mastoiditis. Acute mastoiditis is a suppurative complication of OM with inflammation and potential destruction of the mastoid air spaces. The disease progresses from a periostitis to an osteitis with mastoid abscess formation. Posterior auricular tenderness, swelling, and erythema, in addition to the signs of OM, are present. The pinna is displaced downward and outward. Radiographs or computed tomography scan of the mastoid reveals clouding of the air cells, demineralization, or bone destruction. Treatment includes systemic antibiotics and drainage if the disease has progressed to abscess formation.
OM with effusion is the most frequent sequela of acute OM and occurs most frequently in the first 2 years of life. Persistent middle ear effusion may last for many weeks or months in some children but usually resolves by 3 months following infection. Evaluating young children for this condition is part of all well-child examinations.
Conductive hearing loss should be assumed to be present with persistent middle ear effusion; the loss is mild to moderate and often is transient or fluctuating. Glue ear is used to describe the presence of a viscous, gluelike effusion that is produced when the chronically inflamed middle ear mucosa produces an excess of mucus that, because of absence of the normal clearance of the middle ear cavity, is retained for prolonged periods.
Normal tympanograms after 1 month of treatment obviate the need for further follow-up. In children at developmental risk or with frequent episodes of recurrent acute OM, 3 months of persistent effusion with significant bilateral hearing loss is a reasonable indicator of need for intervention with insertion of pressure equalization tubes.

PREVENTION

Parents should be encouraged to continue exclusive breastfeeding as long as possible and should be cautioned about the risks of bottle-propping and of children taking a bottle to bed. The home should be a smoke-free environment.
Children identified at high-risk for recurrent acute OM are candidates for prolonged courses of antimicrobial prophylaxis, which can reduce recurrences significantly. Amoxicillin (20 to 30 mg/kg/day) or sulfisoxazole (50 mg/kg/day) given once daily at bedtime for 3 to 6 months or longer is used for prophylaxis.
The conjugate S. pneumoniae vaccine reduces pneumococcal OM caused by vaccine serotypes by 50%, all pneumococcal OM by 33%, and all OM by 6%. Annual immunization against influenza virus may be helpful in high-risk children.

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