The microbiological testing of ear discharge is conducted to investigate the microbial causes of otitis externa and otitis media.
Otitis externa
Contamination of the external auditory meatus (ear canal) generally resembles contamination of the skin and soft tissues elsewhere in the body. However, there are some notable differences. The ear canal is narrow, and foreign bodies and fluids can get trapped, irritating the surface tissue. Otitis extern can be divided into several categories: acute localized, acute diffuse, chronic, and malignant. However, except for malignant otitis externa, other external otitis are rarely differentiated in clinical practice.
I. Acute localized otitis externa
Acute localized otitis externa is usually caused by Staphylococcus aureus.
II. Acute diffuse otitis externa
Acute diffuse otitis externa is a common disease in adults with frequent relapses. It is also known as "swimmer's ear" and occurs mainly in warm and humid conditions. Many bacteria cause this infection, the most common being Pseudomonas aeruginosa and Staphylococcus aureus. Rarely acute diffuse otitis externa is caused by anaerobic microorganisms derived from the oropharynx.
III. Chronic otitis externa
Chronic otitis externa is caused by colonization with E. coli and fungi, and the best treatment involves local cleansing rather than antibiotics.
IV. Malignant otitis externa
Clinically, the most crucial form of otitis externa is malignant otitis externa. Malignant otitis externa is a severe necrotic inflammation that spreads from the squamous epithelium of the ear canal to surrounding soft tissues, blood vessels, cartilage, and bones. People with diabetes, the elderly, and immunosuppressed patients are at risk for developing the disease. It is a life-threatening condition with a significant risk of neurological involvement and paralysis of the facial nerve. Pseudomonas aeruginosa almost always causes it.
Otitis media
Acute otitis media is defined by the coexistence of fluid in the middle ear and signs and symptoms of acute disease. It can occur when flora of the mouth colonizes the Eustachian trumpet and is not treated by the middle ear defense mechanisms. Otitis media is a common condition in children with frequent relapses. Treating mild otitis media effectively is essential, as possible complications include hearing loss. This, in turn, could adversely affect children's speech and behavior development.
I. Acute otitis media
The most common microorganisms causing this infection are S. pneumoniae, H. influenzae, and M. catarrhalis. The least common causes are S. pyogenes, S. aureus, and some Gram-negative bacteria. Respiratory syncytial virus (RSV) and parainfluenza viruses have been isolated from patients with otitis media and may play a role in the etiology of the disease, especially in children.
II. Chronic suppurative otitis media
Chronic otitis media is highly destructive and persistent and can cause irreversible damage, such as hearing loss. The most common bacterial cause is Pseudomonas, followed in 25% of patients from methicillin-resistant Staphylococcus aureus (MRSA) and anaerobic bacteria.
Fungal otitis
Fungal infection of the ear is a superficial, chronic, or subcutaneous infection of the external ear canal. Partial deafness may be caused by obstruction of the external auditory canal with fungal hyphae. Fungi associated with external ear infections are Aspergillus species, Scedosporium apiospermum (Pseudallescheria boydii), and other fungi and yeast.
Important Note
Laboratory test results are crucial for diagnosing and monitoring all pathological conditions. 70% and 80% of diagnostic decisions are based on laboratory tests. Correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased."
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be analyzed based on each case and family history, clinical findings, and the results of other laboratory tests and information. Your physician should explain the importance of your test results.
At Diagnostiki Athinon, we answer any questions you may have about the test you perform in our laboratory and contact your doctor to ensure you receive the best possible medical care.
