Otitis Externa

Otitis externa (also known as external otitis or swimmer’s ear) is an infection of the external auditory canal that is most often caused by acute bacterial infection and is frequently associated with hot, humid weather and water exposure. Patients commonly present with ear pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, pruritus, discharge, and hearing loss Hearing loss Hearing loss, also known as hearing impairment, is any degree of impairment in the ability to apprehend sound as determined by audiometry to be below normal hearing thresholds. Clinical presentation may occur at birth or as a gradual loss of hearing with age, including a short-term or sudden loss at any point. Hearing Loss. The diagnosis is made clinically. Most types of otitis externa are treated with topical antibiotic therapy. Complications include periauricular cellulitis Cellulitis Cellulitis is a common infection caused by bacteria that affects the dermis and subcutaneous tissue of the skin. It is frequently caused by Staphylococcus aureus and Streptococcus pyogenes. The skin infection presents as an erythematous and edematous area with warmth and tenderness. Cellulitis and malignant otitis externa.

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Overview

Definition

Otitis externa is an infection of the external auditory canal.

Epidemiology

  • Incidence: 4 of 1000 people annually in the United States 
  • Approximately 10% of people develop otitis externa in their lifetime.
  • Age:
    • Occurs in all age groups
    • Most common in children
  • More likely to occur in the summer because of:
    • Humidity
    • Participation in water activities

Etiology

  • Bacterial infection (most cases):
    • Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa 
    • Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus
    • Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus epidermidis
    • Proteus Proteus Proteus spp. are gram-negative, facultatively anaerobic bacilli. Different types of infection result from Proteus, but the urinary tract is the most common site. The majority of cases are caused by Proteus mirabilis (P. mirabilis). The bacteria are part of the normal intestinal flora and are also found in the environment. Enterobacteriaceae: Proteus vulgaris
    • Escherichia coli Escherichia coli The gram-negative bacterium Escherichia coli is a key component of the human gut microbiota. Most strains of E. coli are avirulent, but occasionally they escape the GI tract, infecting the urinary tract and other sites. Less common strains of E. coli are able to cause disease within the GI tract, most commonly presenting as abdominal pain and diarrhea. Escherichia coli
  • Fungal infection (rare):
    • Candida Candida Candida is a genus of dimorphic, opportunistic fungi. Candida albicans is part of the normal human flora and is the most common cause of candidiasis. The clinical presentation varies and can include localized mucocutaneous infections (e.g., oropharyngeal, esophageal, intertriginous, and vulvovaginal candidiasis) and invasive disease (e.g., candidemia, intraabdominal abscess, pericarditis, and meningitis). Candida/Candidiasis albicans
    • Aspergillus niger

Risk factors

  • Swimming or other water exposure
  • Hot, humid weather
  • Trauma (including cleaning with cotton swabs)
  • Ear canal occlusion:
    • Cerumen
    • Foreign body
    • Hearing aids
    • Headphones
  • Dermatologic conditions:
    • Eczema Eczema Atopic dermatitis, also known as eczema, is a chronic, relapsing, pruritic, inflammatory skin disease that occurs more frequently in children, although adults can also be affected. The condition is often associated with elevated serum levels of IgE and a personal or family history of atopy. Skin dryness, erythema, oozing, crusting, and lichenification are present. Atopic Dermatitis (Eczema)
    • Contact dermatitis
    • Psoriasis Psoriasis Psoriasis is a common T-cell-mediated inflammatory skin condition. The etiology is unknown, but is thought to be due to genetic inheritance and environmental triggers. There are 4 major subtypes, with the most common form being chronic plaque psoriasis. Psoriasis
  • Radiation therapy
  • Immunosuppression:
    • HIV/AIDS
    • Diabetes
    • Chemotherapy

Pathophysiology

Defense mechanisms Defense mechanisms Defense mechanisms are normal subconscious means of resolving inner conflicts between an individual's subjective moral sense and their thoughts, feelings, or actions. Defense mechanisms serve to protect the self from unpleasant feelings (anxiety, shame, and/or guilt) and are divided into pathologic, immature, mature, neurotic, and other types. Defense Mechanisms of the ear

  • Tragus and conchal cartilage Cartilage Cartilage is a type of connective tissue derived from embryonic mesenchyme that is responsible for structural support, resilience, and the smoothness of physical actions. Perichondrium (connective tissue membrane surrounding cartilage) compensates for the absence of vasculature in cartilage by providing nutrition and support. Cartilage → prevent the entrance of foreign bodies
  • Hair follicles and isthmus narrowing → stop the entry of contaminants
  • Cerumen → creates an acidic environment → inhibits bacterial and fungal growth

Pathogenesis of otitis externa

  • Breakdown of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin–cerumen barrier is caused by:
    • Damage to epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium
    • ↓ Quantity and quality of cerumen
    • Moisture accumulation
    • Obstruction of the ear canal
  • ↑ pH of the ear canal → ear canal becomes a prime breeding ground for microscopic organisms → infection
  • Inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation and edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin → purulent exudate

Clinical Presentation and Diagnosis

Symptoms

  • Ear pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
  • Pruritus
  • Fullness
  • Discharge (otorrhea)
  • Hearing loss

Physical examination

  • Tenderness with tragal pressure 
  • Pain with manipulation of the auricle
  • Edema and erythema of the ear canal
  • Yellow, white, gray, or brown purulent debris
  • On pneumatic otoscopy, the tympanic membrane is mobile.

Diagnosis

The diagnosis of otitis externa is based on the history and physical examination. Culture of the ear canal or discharge is indicated for severe, recurrent, or chronic cases.

Management

Management

  • Remove cerumen, desquamated skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin, and purulent material.
  • Protect ear from water.
  • Pain relief:
    • NSAIDs
    • Acetaminophen Acetaminophen Acetaminophen is an over-the-counter nonopioid analgesic and antipyretic medication and the most commonly used analgesic worldwide. Despite the widespread use of acetaminophen, its mechanism of action is not entirely understood. Acetaminophen
    • Opioids Opioids Opiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates. Opioid Analgesics for severe pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
  • Topical antibiotic otic drops:
    • Polymyxin B plus neomycin
    • Ofloxacin
    • Ciprofloxacin
    • Combined preparations with topical steroids can help with pruritus and inflammation.
  • An ear wick can be placed to facilitate medication delivery in patients with significant ear canal edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema.

Prognosis

  • Symptom improvement begins about 36–48 hours after initiation of treatment.
  • Completely resolves in about 6 days

Complications

Periauricular cellulitis Cellulitis Cellulitis is a common infection caused by bacteria that affects the dermis and subcutaneous tissue of the skin. It is frequently caused by Staphylococcus aureus and Streptococcus pyogenes. The skin infection presents as an erythematous and edematous area with warmth and tenderness. Cellulitis

  • Erythema, edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema, and warmth develop around the auricle.
  • Pain is mild.
  • Systemic symptoms are absent.

Malignant otitis externa

Also known as necrotizing otitis externa, this is an invasive, life-threatening infection of the external auditory canal and skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull base.

Etiology:

  • Almost always caused by Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa
  • Risk factors:
    • Elderly
    • Diabetes mellitus Diabetes mellitus Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus
    • HIV

Clinical presentation:

  • Extreme otalgia and otorrhea
  • Granulation tissue may be visible in the inferior portion of the external auditory canal.
  • Can lead to cranial nerve palsies if the disease progresses to osteomyelitis Osteomyelitis Osteomyelitis is an infection of the bone that results from the spread of microorganisms from the blood (hematogenous), nearby infected tissue, or open wounds (non-hematogenous). Infections are most commonly caused by Staphylococcus aureus. Osteomyelitis of the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull base and temporomandibular joint

Diagnosis:

  • Cultures of ear canal drainage
  • CT scan:
    • Bony erosion
    • Middle ear radiolucency
  • Biopsy to rule out malignancy

Management:

  • IV antibiotic therapy:
    • Ciprofloxacin 
    • Piperacillin–tazobactam
    • Cefepime or ceftazidime
    • Meropenem
  • Surgical debridement is rarely needed for extensive infection.

Complications:

  • Cranial nerve palsies
  • Meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis 
  • Brain abscess Brain abscess Brain abscess is a life-threatening condition that involves the collection of pus in the brain parenchyma caused by infection from bacteria, fungi, parasites, or protozoa. The most common presentation is headache, fever with chills, seizures, and neurological deficits. Brain Abscess
  • Dural sinus thrombophlebitis

Differential Diagnosis

  • Contact dermatitis: Persistent edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema and erythema of the ear canal and auricle despite adequate otitis externa treatment can indicate an allergic reaction. This reaction can be caused by ototopical medication, cosmetics, or shampoos. Pruritus and erythema are the primary symptoms, and vesicles can be seen, usually due to rubbing and itching. The diagnosis is made clinically. Management involves cessation of the causative substance.
  • Chronic suppurative otitis media: a complication of persistent acute otitis media Acute Otitis Media Acute otitis media is an infection in the middle ear characterized by mucosal inflammation and retention of fluid. The most common pathogens are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. The condition can present with fever, otalgia, and diminished hearing. Acute Otitis Media with perforation: Symptoms include otorrhea, otalgia, hearing loss Hearing loss Hearing loss, also known as hearing impairment, is any degree of impairment in the ability to apprehend sound as determined by audiometry to be below normal hearing thresholds. Clinical presentation may occur at birth or as a gradual loss of hearing with age, including a short-term or sudden loss at any point. Hearing Loss, tinnitus, or vertigo Vertigo Vertigo is defined as the perceived sensation of rotational motion while remaining still. A very common complaint in primary care and the ER, vertigo is more frequently experienced by women and its prevalence increases with age. Vertigo is classified into peripheral or central based on its etiology. Vertigo. The diagnosis is made clinically.  The tympanic membrane is often partially visible and not movable by pneumatic insufflation. A tympanic membrane perforation or retraction pockets may also be seen. Management primarily involves topical fluoroquinolones Fluoroquinolones Fluoroquinolones are a group of broad-spectrum, bactericidal antibiotics inhibiting bacterial DNA replication. Fluoroquinolones cover gram-negative, anaerobic, and atypical organisms, as well as some gram-positive and multidrug-resistant (MDR) organisms. Fluoroquinolones
  • Carcinoma of the ear canal: a rare disease that should always be considered if there is an abnormal growth in the ear canal or a lack of response to prolonged otitis externa therapy: Common symptoms of carcinoma of the ear canal include mild pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain and bloody otorrhea. A friable lesion with surrounding purulence on an otoscopic exam may be seen. Hearing loss and facial paralysis are late signs. Diagnosis is made clinically and confirmed by biopsy. 
  • Psoriasis Psoriasis Psoriasis is a common T-cell-mediated inflammatory skin condition. The etiology is unknown, but is thought to be due to genetic inheritance and environmental triggers. There are 4 major subtypes, with the most common form being chronic plaque psoriasis. Psoriasis: an inflammatory skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin condition that commonly involves the external ear canal and leads to redness and scaling that often extends to the conchal bowl and auricle: The clinical appearance of psoriasis in the external auditory canal varies. The diagnosis is made clinically.  Management can include steroids and retinoids. More severe cases may require high-dose steroids, light therapy, or biologics.

References

  1. Goguen, L. A. (2020). External otitis: Pathogenesis, clinical features, and diagnosis. In Kunins, L. (Ed.), UpToDate. Retrieved March 31, 2021, from https://www.uptodate.com/contents/external-otitis-pathogenesis-clinical-features-and-diagnosis
  2. Goguen, L. A. (2019). External otitis: Treatment. In Kunins, L. (Ed.), UpToDate. Retrieved March 31, 2021, from https://www.uptodate.com/contents/external-otitis-treatment
  3. Grandis, J. R., Yu, V. L. (2019). Malignant (necrotizing) external otitis. In Bloom, A. (Ed.), UpToDate. Retrieved March 31, 2021, from https://www.uptodate.com/contents/malignant-necrotizing-external-otitis
  4. Kumar, V., Abbas, A. K., Aster, J. C. Robbins. (2015). Cotran Pathologic Basis of Disease. Philadelphia: Elsevier Saunders.
  5. Lustig, L. R., Limb, C. J. (2021). Chronic otitis media, cholesteatoma, and mastoiditis in adults. UpToDate. Retrieved March 31, 2021, from https://www.uptodate.com/contents/chronic-otitis-media-cholesteatoma-and-mastoiditis-in-adults
  6. Rubin, M.A., Ford, L.C., and Gonzales, R. (2018). Sore throat, earache, and upper respiratory symptoms. In Jameson, J., Fauci, A. S., Kasper D. L., Hauser S. L., Longo, D. L., Loscalzo, J. (Eds.), Harrison’s Principles of Internal Medicine, 20th ed. McGraw-Hill.
  7. Kesser, B. W. (2020). External otitis (acute). MSD Manual Professional Version. Retrieved April 8, 2021, from https://www.msdmanuals.com/professional/ear,-nose,-and-throat-disorders/external-ear-disorders/external-otitis-acute
  8. Kesser, B. W. (2020). Malignant external otitis. MSD Manual Professional Version. Retrieved April 8, 2021, from https://www.msdmanuals.com/professional/ear,-nose,-and-throat-disorders/external-ear-disorders/malignant-external-otitis
  9. Waitzman, A. A. (2020). Otitis externa. In Elluru, R. G. (Ed.), Medscape. Retrieved April 8, 2021, from https://emedicine.medscape.com/article/994550-overview
  10. Nussenbaum, B. (2020). Malignant otitis externa. In Meyers, A.D. (Ed.), Medscape. Retrieved April 8, 2021, from https://emedicine.medscape.com/article/845525-overview
  11. Medina-Blasini, Y., Sharman, T. (2020). Otitis externa. StatPearls. Retrieved April 8, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK556055/

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