Table of Contents
Definition of Acute Otitis Media
Acute otitis media is defined as the acute inflammation of the middle ear which is associated with symptoms and signs suggestive of inflammation. To differentiate between acute and chronic otitis media, the definition includes a maximum duration of three weeks of semiology to be considered as acute otitis media.
Epidemiology of Acute Otitis Media
Acute otitis media is a very common condition especially among young children with an estimated 70 % of all children younger than 2 years to develop the condition at least once. Other studies put the incidence of acute otitis media at approximately 79 % per year.
Acute otitis media is clearly more common among children aged 3 to 18 months. It seems that the maximum incidence of acute otitis media is in children aged 6 to 11 months. For unclear reasons, the incidence of acute otitis media is slightly higher in boys compared to girls.
Infants who develop otitis media very early in their life are considered as otitis-prone and they are at risk of developing recurrent acute otitis media later in life. The condition is also clearly affected by ethnicity with higher incidence among Native Americans and Inuits. Additionally, African American children have a lower incidence of acute otitis media compared to white children.
Etiology of Acute Otitis Media
Different etiologies have been associated with acute otitis media which can be easily separated into viral and bacterial pathogens. Therefore, acute otitis media is an inflammatory condition of the middle ear that has an infectious etiology.
Viral agents that can cause acute otitis media include the respiratory syncytial virus, which is also associated with bronchiolitis and pneumonia. Respiratory syncytial virus infection has been associated with long-term risk of respiratory complications which include asthma.
Pathogenic bacterial infections of the middle ear are found as the etiology of acute otitis media in at least half of the cases. Different organisms have been identified which include Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes.
Streptococcus pneumoniae is considered as the most common etiology of acute otitis media regardless of age. At least, 50% of the cases of acute otitis media are caused by streptococcus pneumoniae.
Approximately, 20% of the cases are caused by Haemophilus influenzae. While streptococcus pneumoniae is identified in virtually any age group of acute otitis media patients, haemophilus influenzae is thought to be more common among older children and recurrent acute otitis media.
Moraxella catarrhalis is thought to be associated with viral acute otitis media since the bacterium was found to have an interaction with different viral agents known to cause acute otitis media.
Finally, streptococcus pyogenes is the fourth common cause of bacterial acute otitis media. Due to the introduction of penicillins, streptococcus pyogenes cases of otitis media and associated complications are declining.
While these bacterial and viral pathogens are known to cause acute otitis media in healthy children, certain risk factors are known to be associated with increased severity of the condition or an increased risk of recurrent acute otitis media. Premature birth, family history of acute otitis media, certain races, people with craniofacial anomalies and immunocompromised children are considered as otitis-prone. This term indicates that these populations are more likely to develop recurrent disease later in life.
Pathophysiology of Acute Otitis Media
The different viral and bacterial agents associated with acute otitis media are responsible for acute inflammation of the nasopharynx and the Eustachian tube. This is associated with increased pressure in the middle ear and stasis. Most likely, viral inflammation is the first step in the pathology which is followed by bacterial colonization due to stasis.
Our current understanding of acute otitis media allows us to theorize that viral infection alone of the middle ear is not enough to cause the symptoms and signs of acute otitis media. Secondary bacterial infection of the middle ear is the most likely cause of the semiology of acute otitis media.
Clinical Presentation of Acute Otitis Media
The symptoms of acute otitis media in neonates are different from older children. Neonates usually present with non-specific symptoms such as irritability, feeding difficulties and/or lethargy. Infants and older children complain of fever, symptoms of an upper respiratory tract infection, pain in the ear and ear tugging.
Children with recurrent otitis media are prone to hearing difficulties and conductive hearing loss. Ear stuffiness, ear pain and the presence or absence of fever are common findings in older children with acute otitis media.
Perhaps, the most important tool to diagnose acute otitis media is physical examination with pneumatic otoscopy. The direct visualization of the tympanic membrane allows for the demonstration of definite signs of acute otitis media which include reddening, tympanic membrane bulge, and possible tympanic membrane discharge.
Immunocompromised children do not show the typical picture of acute otitis media on pneumatic otoscopy. Instead, they appear septic and their otoscopy shows serous or watery discharge. The threshold to diagnose acute otitis media in these children should be low and such findings are usually enough to make the diagnosis.
Once tympanic membrane perforation occurs, patients usually describe sudden improvement and their fever subsides. The most common sign of acute tympanic membrane perforation is purulent ear discharge.
Diagnostic Workup for Acute Otitis Media
Patients who present with uncomplicated and straight-forward picture of acute otitis media should be treated empirically. Those who develop tympanic membrane perforation, which is common, should undergo culture and sensitivity testing of the purulent discharge.
Patients who develop a high-grade fever, become confused, or develop focal neurological signs might have developed an intracranial abscess or venous thrombosis. Such patients might benefit from a head computerized tomography scan.
Neonates, the immunocompromised, and patients with no response to antibiotic treatment should undergo tympanocentesis. This procedure allows the collection of middle ear aspirate for culture and sensitivity testing. A small needle is introduced through the tympanic membrane. The needle will cause a small hole in the tympanic membrane but this is not associated with any significant complications because the hole is expected to undergo complete healing in one or two days.
Treatment of Acute Otitis Media
The mainstay treatment of acute otitis media remains empirical antibiotic therapy. Amoxicillin or erythromycin-sulfisoxazole are considered as first-line therapy for acute otitis media in children.
Children who do not respond to antibiotics after 48 hours of therapy initiation might have a resistant organism. In this group of children, tympanocentesis should be used to allow for the identification of the infecting organism and defining its antibiotic-sensitivity profile.
Children with confirmed streptococcus pneumoniae infection can receive ceftriaxone, cefotaxime, or rifampin. Use of amoxicillin combined with clavulanic acid is usually effective in the treatment of Haemophilus influenzae otitis media. Moraxella catarrhalis is usually sensitive to macrolides and cephalosporins.