Otitis Media

Otitis media, or inflammation of the middle ear, is one of the most common pediatric diagnoses. Each year there are 24.5 million office visits and over 3.7 million emergency department visits, with direct and indirect costs of $5.7 billion a year.12 and3 Acute otitis media (AOM) (acute suppurative, purulent, or bacterial) is associated with signs and symptoms of inflammation of the middle ear, such as otalgia, otorrhea, fever, irritability, anorexia, or vomiting. 4 Otitis media with effusion (OME) (secretory, nonsuppurative, serous, or mucoid) is a relatively asymptomatic collection of fluid in the middle ear. The duration (not the severity) of OME can be divided into acute (<3 weeks), subacute (3 weeks to 3 months), and chronic (>3 months).5 The most important distinction between OME and AOM is that the signs and symptoms of acute infection (otalgia, otorrhea, and fever) are lacking in OME, but hearing loss may be present in both conditions. 5

ACUTE OTITIS MEDIA Infants and young children are at greatest risk for the development of otitis media, with the peak incidence occurring between 6 and 18 months.1 By 3 years, more than two-thirds of children have had at least one episode of AOM, and one-third have had three or more episodes. 6 The incidence is higher in males, Native Americans, Alaskan and Canadian Eskimos, and children who attend day care, are exposed to tobacco smoke, have a cleft palate or other craniofacial anomaly (e.g., Down syndrome), sleep in a prone position, use a pacifier, have older siblings or parents with a history of ear infections, had their first episode of AOM at less than 6 months of age, or have congenital or acquired immunodeficiency. 1 The incidence is lower in breast-fed infants.1

Middle ear effusion may persist for weeks to months after an episode of AOM. Antibiotic therapy generally sterilizes the effusion but does not clear it from the middle ear space. After the first episode of AOM, 70 percent of children still have a middle ear effusion at 2 weeks, 40 percent at 1 month, 20 percent at 2 months, and 10 percent at 3 months.4

Etiology Bacteria are the most common cause of AOM and can be isolated in a pure culture from the middle ear exudate in 60 to 75 percent of cases. These organisms colonize the nasopharynx and enter the middle ear via the eustachian tube. Streptococcus pneumoniae and Haemophilus influenzae are the most common pathogens [Strep. pneumoniae 30 to 50 percent (most common serotypes, 19, 23, 6, 14, 3, and 18), H. influenzae—primarily nontypable strains—15 to 30 percent], and Moraxella (formerly Branhamella) catarrhalis the third most common organism (7 to 20 percent).6 Of importance is a major change in the increased prevalence of b-lactamase-producing M. catarrhalis (70 to 90 percent) and H. influenzae (30 to 40 percent), which affects antibiotic therapy decisions.7 Strep. pyogenes (group A) and Staphylococcus aureus are each found in 2 percent of cultures.4 Chlamydia pneumoniae may also be a causative organism, especially in those less than 6 months of age.8 However, in infants 6 weeks or less, gram-negative enteric bacilli and S. aureus account for 10 to 20 percent of isolates. Although viruses are rarely recovered from middle ear effusions, recent studies have shown an increased risk of OME following an upper respiratory tract infection due to rhinovirus, respiratory syncytial virus, adenovirus, and influenzavirus A or B.46

Pathophysiology Abnormal function of the eustachian tube appears to be the dominant factor in the pathogenesis of middle ear disease. Two types of tube dysfunction may result in otitis media: obstruction and abnormal patency. Obstruction can result from persistent collapse of the eustachian tube due to increased tubal compliance, an inadequate active opening mechanism, or both. Infants and younger children are susceptible to eustachian tube obstruction because the cartilage that supports the eustachian tube is less stiff than in adults. In addition, an upper respiratory tract infection or allergies can obstruct the eustachian tube and decrease its function. The obstructed eustachian tube prevents equilibration of air pressure between the middle ear and the atmosphere and creates conditions favorable to the development of purulent or sterile effusions. The other type of dysfunction is abnormal patency, which may allow reflux of nasopharyngeal secretions. 5

Clinical Features Classic signs and symptoms of AOM include ear pain (otalgia), otorrhea, and fever; however, ear pulling and irritability may be the only clues in an infant. The most important diagnostic tool is the pneumatic otoscopic examination. Before adequate visualization of the external canal and tympanic membrane (TM) can be achieved, cerumen must be removed from the canal by blunt curettage or by irrigation with warm water.9 The presence or absence of discharge and the position, color, and degree of translucency and mobility of the TM must be assessed. The light reflex is of no diagnostic value. The normal eardrum is translucent and pearly gray but may become reddened with crying. The eardrum should be freely mobile in response to positive and negative pressure by the pneumatoscope; however, retracted TMs have reduced mobility. The TM of AOM is usually opaque, hyperemic, and sometimes bulging, and bony landmarks (long and short process of the malleus) are not easily discernible. However, the most significant sign is the loss of or decrease in mobility of the TM. 59

Tympanometry is a noninvasive diagnostic technique used to determine the compliance of the TM and the middle ear. A fixed tone at a given intensity is delivered through a probe snugly placed in the external ear canal as the air pressure in the canal is varied from positive to negative. The tympanogram is a recording of the acoustic compliance of the middle ear, and patterns obtained are useful in distinguishing a normal ear from one with an effusion. 59 Acoustic reflectometry is a technique that in the uncooperative infant or child is easier to perform than tympanometry (since the instrument does not need to seal the auditory canal). When fluid is present in the middle ear, sound reflection is increased.6

Aspiration of the middle ear is the most definitive method of verifying the presence and type of middle ear effusion and infecting organism; however, its use for this purpose in the emergency department setting is rarely practical. It may be beneficial in (1) children with overwhelming sepsis, (2) immunologically deficient children, (3) neonates, (4) children with persistent symptoms of AOM after more than 48 to 72 h on antimicrobial therapy, or (5) otitis media with confirmed or potential suppurative complications.5 Diagnostic tympanocentesis may be performed by inserting an 18-gauge spinal needle or catheter over a needle attached to a syringe through the inferior portion of the TM. The aspirate should be cultured in blood culture broth and on blood and chocolate agar plates. When therapeutic drainage is required, a myringotomy should be performed. The incision should be made in the lower half of the TM and should be large enough to allow adequate drainage and aeration of the middle ear. Myringotomy may relieve unusually severe otalgia, either at initial examination or at any time during the course of the disease. In addition, it should be performed when a suppurative complication (e.g., meningitis, facial paralysis, or mastoiditis) is present. 56

Treatment Selection of the appropriate antibiotic is based on several factors: (1) knowledge of the likely etiologic agent or recovery of a specific pathogen from middle ear fluid, (2) the efficacy of certain antibiotics against the organism responsible for AOM, (3) antibiotic penetration into middle ear fluid, (4) a history of drug allergy, (5) compliance issues, (6) drug side effects, and (7) treatment failure or success of previous drug regimens for that child. 1,4 Despite the approval of 14 antibiotics by the US Food and Drug Administration for the treatment of AOM (see Table.116-1 for doses and frequency) and the changing antibiotic susceptibility patterns that have emerged over the past few years, amoxicillin [40 to 50 (mg/kg)/day divided tid for 10 days] remains the drug of choice. The preference for this drug is based on calculations that show that amoxicillin would result in clinical treatment failure in 8 to 10 percent of cases of AOM (based on data on organism prevalence, spontaneous clearance rates, and antimicrobial resistance).1

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