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Infections of the Ear
Key Points
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Essentials of diagnosis of otitis media:
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Middle ear effusion must be present as diagnosed by pneumatic otoscopy or tympanometry with
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Moderate to severe bulging of the tympanic membrane or new otorrhea not associated with otitis externa or
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Mild bulging of the tympanic membrane and less than 48 hours of otalgia or erythema of the tympanic membrane
Pearls
- 1.
For a diagnosis of acute otitis externa, there must be a rapid onset (usually within 48 hours) of symptoms and signs of ear canal inflammation.
- 2.
The most common bacterial pathogens contributing to acute otitis media are Streptococcus pneumoniae (35% to 40%), Haemophilus influenzae (30% to 35%), and Moraxella catarrhalis (15% to 25%).
- 3.
Amoxicillin remains the first-line therapy for acute otitis media because approximately 80% of bacterial isolates remain susceptible. Pain is an important symptom of otitis externa and otitis media and needs to be treated appropriately.
- 4.
Acute otitis media in children less than 6 months of age or with severe symptoms and/or bilateral ear involvement from 6 months to 23 months of age should be treated with antibiotics. Asymptomatic children over 2 years of age may be observed without antibiotic therapy.
- 5.
The American Academy of Pediatrics recommends pneumococcal conjugate vaccines and annual influenza vaccines according to the Advisory Committee on Immunization Practices in order to reduce episodes of otitis media related to these pathogens.
Questions
1
What is otitis externa (OE)?
Otitis externa is diffuse inflammation of the skin of the external auditory canal (EAC), which can extend to surrounding structures such as the pinna, tragus, tympanic membrane, and regional lymph nodes.
2
What is the pathogenesis of OE?
OE occurs when the protective mechanisms of the ear canal are disrupted. Cerumen, produced by glands in the cartilaginous ear canal, is bacteriostatic and protects the ear canal by acting as a barrier to moisture. Cerumen is also slightly acidic, which aids in inhibiting infection. If this cerumen layer is disrupted and the skin of the ear canal is traumatized with a cotton swab, fingernail, or other foreign body, an infection may occur. Moist and humid environments also contribute to infections by weakening skin barriers. Almost all AOE is bacterial and Staphylococcus aureus and Pseudomonas aeruginosa are the most common causative organisms.
3
What are the risk factors for acute otitis externa (AOE)? How do you prevent AOE?
Water exposure is the most common culprit associated with AOE as seen in warmer, humid climates or from direct contact with water while bathing or swimming (so-called “swimmer’s ear”). There is a relationship between the bacterial load of water and the development of AOE. There also may be a genetic basis to the development of AOE such as Type A blood group. AOE can be prevented by reducing water exposure in the ear canal. Preventative measures include acidifying ear drops, removal of obstructing cerumen, drying the ear canal with a hair dryer (on a cool setting), ear plug use, and avoidance of direct ear canal trauma.
4
What are the signs and symptoms of AOE?
AOE usually presents as a rapid onset (usually less than 48 hours) of intense ear pain. The pain is often out of proportion to the examination and is exacerbated by palpation of the tragus and pinna. Signs of ear canal inflammation such as erythema, edema, and drainage must also be present. Additional symptoms include purulent ear drainage, otalgia (ear pain), plugged feeling in the affected ear, and debris in the ear canal.
5
What is chronic otitis externa (COE)?
Chronic otitis externa is inflammation of the skin of the EAC lasting more than 6 weeks and can be related to bacterial infection, skin disorders such as eczema, fungus, allergy, chronic otorrhea, or chronic irritation. The pain is often not as severe as acute OE. COE may occur after inadequate treatment of AOE.
6
What is malignant otitis externa? What are other complications of OE?
Malignant otitis externa is an infection of the skull base that can occur after acute or chronic OE. It is most often seen in elderly patients with diabetes and the immunocompromised. The infection can spread intracranially, causing cranial nerve deficits, and is a life-threatening condition requiring intravenous antibiotic therapy and correction of the underlying immunocompromise. Other symptoms of malignant otitis media include a deep stabbing ear pain that worsens with head motion, otorrhea, fever, loss of voice, dysphagia, and facial weakness. Less seriously, OE can spread and cause facial cellulitis.
7
What are other causes of ear pain or otorrhea that may be confused for acute otitis externa?
An infected hair follicle (furunculosis), viral infections, temporomandibular joint syndrome, dental abnormalities, or referred pain from aerodigestive processes can cause otalgia and must be considered when the history and physical examination are not convincing of AOE.
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