What Is Acute Otitis Media(AOM) ?

 

I. Definition 

Acute otitis media (AOM) is primarily an infection of childhood and is also the most common infection in pediatric hospitals.
Acute otitis media is an acute, suppurative infectious that is located in the lining of the middle ear space. The infection can render the function of the Eustachian tube, resulting in the retention and suppuration of retained secretions.

  AOM usually responds promptly to antimicrobial therapy.

II. Epidemiology of acute otitis media

Acute otitis media (AOM) occurs much more commonly in children than in adults. Most cases of AOM occur in young children ages 6 to 24 months. The number of AOM is decreasing due to the introduction of routine pneumococcal vaccination in infants.

III. Microbiology

The majority of the microbiology of acute otitis media is bacterial pathogens( Streptococcus pneumoniae and non-typeable Haemophilus influenzae, with Moraxella catarrhalis the third most common bacterial etiology.
 Streptococcus pneumoniae : one of the most important bacterial causes of AOM. PCV13 and the 23-valent pneumococcal polysaccharide vaccine (PPSV23) are recommended by the centers for disease control and prevention for adults.
 Haemophilus influenzae : AOM due to H. influenzae in patients of all ages is due to nontypeable strains in the majority of patients.
 Moraxella catarrhalis : it is responsible for 3 to 14 percent of AOM in children and is the third most common otopathogen.
 Staphylococcus aureus: it is uncommon in children. S. aureus is known to occur in patients with chronic suppurative otitis media(CSOM) and may be associated with persistent otorrhea following insertion of tympanostomy tubes,
 Group A streptococcus: it is uncommon to cause of AOM.However, it is found to be the most common cause of severe AOM requiring hospitalization.
 Less common or rare :
 Mycoplasma pneumonia, Diphtheritic otitis, tuberculous otitis, and autogenous tetanus, and otitis media due to Chlamydia trachomatis.

 The risks of AOM and its complications are also increased in patients who have malignancy, use immunosuppressive drugs, or have a history of previous radiation of the nasopharyngeal region.

IV. Clinical findings 

In adults: upper respiratory tract infection or exacerbation of seasonal allergic rhinitis often precedes the onset of AOM.In adults, AOM is typically unilateral and is associated with otalgia(ear pain) and decreased or muffled hearing. If the tympanic membrane has ruptured, the patient may report a sudden relief of pain, possibly accompanied by purulent otorrhea. Conductive hearing loss can occur due to the presence of middle ear fluid.
Other symptoms such as high fever, severe pain behind the ear, or facial paralysis, suggest unusual complications.
 Diagnosis with otoscopy :
 Key features include :
 Bulging tympanic membrane
 Reduced mobility of the tympanic membrane
Examination typically demonstrates tympanic membrane bugling, opacification, erythema, and poor mobility when pneumatic pressure is applied using a pneumatic otoscope. When there is the presence of fluid in the middle ear, the tympanic membrane appears cloudy, yellowish, or opaque.

V. Differential diagnosis 

Otitis media with effusion (OME): it is defined by the presence of middle ear fluid without acute signs of bacterial infection or illness. OME can be the result of a recent viral infection, barotrauma, or allergy and can precede or follow an episode of AOM. Otoscopic findings of OME include visible fluid (yellowish, but sometimes clear) behind an intact tympanic membrane.
Chronic otitis media(COM): It is diagnosed when there is subacute or chronic tympanic membrane perforation which occurs in the setting of chronic ear infection or recurrent infections. Bening COM is characterized by a tympanic membrane perforation without accompanying drainage. In COM with effusion, there is continuous, typically straw-colored, serous drainage through the perforated tympanic membrane. Chronic suppurative otitis media (CSOM) is defined by chronic purulent drainage through the perforated tympanic membrane.
External otitis (otitis externa): it is characterized by a painful, inflamed, erythematous ear canal, occasionally involving a small portion of the auricle. The tympanic membrane in the majority of cases appears normal, without bulging or retraction, although there might be some minimal erythema present.
Herpes zoster infection : it is developed of the classic dermatomal vesicular rash. The Ramsay Hunt syndrome (herpes zoster oticus) is characterized by the triad of ipsilateral facial paralysis, ear pain, and vesicles involving the auditory canal and auricle, and can also cause vertigo.

VI. Treatment of acute otitis media

Antibiotics are the mainstay of treatment of uncomplicated acute otitis media(AOM).
Choice of initial antibiotic: our choice is amoxicillin-clavulanate.If the patients cannot use amoxicillin-clavulanate, we typically use a cephalosporin.
In patients without severe reactions, and who do not know allergy to cephalosporin, we use :
 Cefdinir
 Cefpodoxime
 Cefuroxime
 Ceftriaxone
For patients with a severe allergy to beta-lactam antibiotics, we use doxycycline or a macrolide: doxycycline, azithromycin, clarithromycin.

VII. Other possible complications 

 Mastoiditis: Mastoiditis can occur at any age but is far more common in children than adults, when it occurs in older adults, it may be particularly severe. Suppurative mastoiditis may present with fever, posterior ear pain and/or local erythema over the mastoid bone, edema of the pinna, or a posteriorly and downwardly displaced auricle.
 Labyrinthitis: Rarely, purulent (suppurative) labyrinthitis can develop, caused by direct extension of the AOM infection into the inner ear. This presents with more intense vertigo, tinnitus, hearing loss, vomiting, and nausea.
 Facial paralysis: it is a rare complication of AOM through 2 different mechanisms. First, there can be a direct infection from the middle ear to the nerve itself, as the inflamed nerve swells within this confined channel. Second, the erosion of the bone overlying the facial nerve can directly compress the facial nerve. This typically occurs in the tympanic or vertical mastoid segment of the nerve.
 Hearing loss: it results from both acute and chronic ear infections.