37 Infections of the Ear Flashcards
What is otitis externa (OE)?
What is otitis externa (OE)?
Otitis externa is an infection 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.
What is the pathogenesis of OE?
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 also protects the ear canal by acting as a barrier to moisture. Cerumen is also slightly acidic, which aids in inhibiting infection. Cotton swabs can contribute to OE not only by removing the protective cerumen, but also by injuring the ear canal skin. If the skin of the ear canal is traumatized with a fingernail, ear plugs or foreign body, an infection may occur as well. Moist and humid environments also contribute to infections by weakening skin barriers. Staphylococcus aureus and Pseudomonas aeruginosa are the most common causative organisms.
What are the risk factors for acute otitis externa (AOE)? How do you prevent AOE?
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 humid climates or from direct contact with water while bathing or swimming (so-called “swimmer’s ear”). 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.
What are the signs and symptoms of AOE?
What are the signs and symptoms of AOE?
AOE usually presents as a rapid onset of intense ear pain. The pain is often out of proportion to exam 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. Ninety-eight percent of AOE is bacterial. Signs and symptoms include purulent ear drainage, otalgia (ear pain), plugged feeling in the affected ear, ear canal swelling, and debris in the ear canal. To be classified as acute the pain should be of less than 48 hours duration. Drainage from the ear canal may cause eczema of the outer ear.
What is chronic otitis externa (COE)?
What is chronic otitis externa (COE)?
Chronic otitis externa is defined as otorrhea with symptoms of otitis externa that are present for more than 6 weeks. The pain is often not as severe as acute OE. COE may occur after inadequate treatment of AOE.
What is malignant otitis externa? What are other complications of OE?
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 and cause 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 is made worse with head motion, otorrhea, fever, loss of voice, dysphagia, and facial weakness. Less seriously, OE can spread and cause facial cellulitis. Chronic drainage from the ear canal can also cause irritation of the skin of the ear and neck.
How do you treat OE?
How do you treat OE?
OE is best treated by debriding the ear of desquamated skin and cerumen, restoring the normal pH, topical antimicrobial therapy, and removal of causative agents. Fluoroquinolone drops are first-line therapy. If any systemic symptoms are present or the infection has spread outside the ear canal, systemic antibiotics that cover S. aureus are appropriate. If patients are predisposed to recurrent OE, 2 to 3 drops of a 1 : 1 solution of white vinegar and 70% ethyl alcohol can be instilled into the ear before and after swimming.
What is bullous myringitis?
What is bullous myringitis?
Bullous myringitis is the formation of serous or hemorrhagic bullae on the tympanic membrane. It is associated with viral, Streptococcus pneumoniae, or staphylococcal infections. It is often very painful and may cause a conductive hearing loss. Supportive treatment is indicated including analgesics and anti-inflammatory medications. If signs of bacterial infection are present, then topical or oral antibiotics are appropriate.
What is otitis media (OM)? What are the predisposing factors for OM?
What is otitis media (OM)? What are the predisposing factors for OM?
Otitis media is an infection of the middle ear space. It is common in younger children secondary to an immature immune system, eustachian tube dysfunction, and unfavorable anatomy. Other predisposing factors include colonization of the nasopharynx with otitis pathogens, upper respiratory infection, smoke exposure, bottle feeding, time of year, daycare attendance, and genetic susceptibility.
What role does the eustachian tube play in otitis media?
What role does the eustachian tube play in otitis media?
The eustachian tube (ET) runs from the anterior middle ear to the nasopharynx, and equalizes the pressure in the middle ear space. It is bony in its proximal portion and cartilaginous in its distal portion and is associated with four muscles: salpingopharyngeus, tensor veli palatini, tensor tympani, and levator veli palatine. The ET intermittently opens in response to different actions on these muscles including yawning, talking, and performing a Valsalva maneuver. The middle ear space is under constant negative pressure, and equalization by the ET prevents build-up of fluid. If the ET is dysfunctional for any reason, then fluid build-up occurs causing a middle ear effusion. Common causes for ET dysfunction include anatomic variants and viral infections with concomitant swelling. In children, the eustachian tube is flatter and less rigid, which can contribute to dysfunction (Figure 37-1). The fluid can then become infected from exposure to pathogens that are found in the nasopharynx.
What are the most common bacterial pathogens found in OM?
What are the most common organisms found in mastoiditis?
What are the most common bacterial pathogens found in OM? What are the most common organisms found in mastoiditis?
Classically, the most common bacterial pathogens contributing to OM are Streptococcus pneumoniae (35% to 40%), Haemophilus influenza (30% to 35%), and Moraxella catarrhalis (15% to 25%). Streptococcus pyogenes and S. pneumoniae are the most common pathogens found in mastoiditis. With the advent of the pneumococcal vaccine there has been a decrease in the number of infections from S. pneumoniae but an increase in infections from other bacteria such as Staphylococcus aureus and H. influenzae. There is a trend for an overall decrease in OM by about 6% to 7% since vaccinations were begun.
What are biofilms and what is their role in otitis media?
What are biofilms and what is their role in otitis media?
Biofilms are groups of microorganisms that reside in an extracellular matrix. The extracellular matrix is resistant to antibiotic penetration. Additionally, different bacteria in the biofilm can share host defense mechanisms and resistant genes. Biofilms have been found in the middle ear and nasopharynx of children with otitis media. It is thought that biofilms contribute to OM by shedding planktonic bacteria and inducing mucosal inflammation.
What examination techniques are used in the diagnosis of otitis media?
What examination techniques are used in the diagnosis of otitis media?
Any obstructing cerumen should be cleared from the ear canal to see the tympanic membrane. This can be done with an open operating otoscope (Figure 37-2) or under a microscope. Irrigation of the ear canals should be used with caution in case there is an unrecognized tympanic membrane perforation. Water in the ear canal can also predispose to otitis externa. The tympanic membrane is examined for color, thickness, bulging, loss of landmarks, and presence of effusion. Loss of the light reflex is not specific for otitis media. Next, pneumatic otoscopy is performed with an insufflator bulb attached to a closed head otoscope. Gentle pressure is applied, which will cause a pressure change in the canal. If an effusion is present the ear drum will not move; in the absence of an effusion the ear drum will move. Only gentle pressure is needed. Too much pressure can cause pain. If pneumatic otoscopy cannot be performed, then tympanometry can be used to establish presence of an effusion.
What tips for pneumotoscopy will help you perform an ear examination?
What tips for pneumotoscopy will help you perform an ear examination?
- Choose largest ear speculum to ensure a tight seal.
- Insert the speculum into only the outer one third of the external canal to avoid pain from pressure on the bony canal.
- Insert the speculum after compressing the bulb slightly, then release to check for movement. This helps avoid discomfort and can diagnose negative ear pressure.
- Use only gentle pressure to minimally flutter the tympanic membrane.
What antibiotics are used in the treatment of otitis media?
What antibiotics are used in the treatment of otitis media?
Amoxicillin remains the first-line therapy because approximately 80% of bacterial isolates remain susceptible. High dosages are used to help avoid resistance. Amoxicillin with clavulanic acid is used when the patient has failed clinically after 48 to 72 hours or has had amoxicillin in the last 30 days. In patients with penicillin sensitivity without severe reactions, cephalosporins are used. For children with IgE mediated allergic reactions, trimethoprim-sulfamethoxazole, clindamycin or a macrolide is used. Intramuscular ceftriaxone is usually reserved for failures of oral therapies (Tables 37-1 and 37-2).
What are tympanostomy tubes?
How do tympanostomy tubes help OME and AOM?
What are tympanostomy tubes? How do tympanostomy tubes help OME and AOM?
Tympanostomy tube placement is the most common ambulatory surgery performed in the United States. The tubes are small cylinders usually with a flange or collar that sits in the tympanic membrane (Figure 37-3). The role of the tube is to drain fluid and equalize middle ear pressure. In children with acute otitis media, they prevent a build-up of middle ear fluid and subsequent inflammation and infection. In otitis media with effusion, they remove the effusion allowing for improvement in hearing. On average the tubes last for 6 months to a year. They are pushed out of the ear drum by the natural desquamation of the epithelial layer of the tympanic membrane. Tympanostomy tubes are the main surgical treatment for recurrent otitis media and otitis media with effusion. There are specific surgical indications for each disease process.
