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  • Writer's pictureDr. Koralla Raja Meghanadh

Diffuse Otitis Externa: Causes, Symptoms, and Treatment

Otitis externa, or outer ear infection, affects the external part of the ear. This condition is classified broadly into two types based on its characteristics.

  1. Diffuse Otitis Externa

  2. Circumscribed Otitis Externa

While both diffuse and circumscribed otitis externa involve infection of the external ear canal, they differ in the extent and distribution of the infection. In circumscribed otitis externa, infection is localized to a specific area at the end of the ear canal. Meanwhile, in diffuse otitis externa, as the name suggests, infection affects the entire external ear canal. This infection is caused by bacterial or fungal infection or both and can lead to various symptoms and complications if left untreated. This article delves into the causes, symptoms, treatment, and prevention of diffuse otitis externa.


Diffuse Otitis Externa in Right ear with discharge and perforated ear drum
Diffuse Otitis Externa in Right ear with discharge and perforated eardrum

What is Diffuse Otitis Externa?

"Diffuse" indicates that the infection is not localized but instead spreads across the ear, "otitis" signifies infection is in the ear, and "external" specifies that the condition is restricted to the external part of the ear, i.e., the ear canal.


Causes of Diffuse Otitis Externa

Diffuse otitis externa can be caused by various factors, predominantly by the Pseudomonas organism, which resides harmlessly in the ear canal as a commensal bacterium. This means it stays in the ear canal without causing disease when the balance between the bacteria and the body's immune system is maintained. However, when the body's immune system is compromised, the Pseudomonas organism can lead to infection. This can be caused by either local or systemic factors like

  • Water exposure in the ear canal: When water enters the ear canal, it can disrupt the integrity of the ear skin lining. This makes the skin more susceptible to damage, which can lead to ear infections.

  • Prolonged moisture exposure: Prolonged exposure to moisture, particularly in swimmers, creates an inflammatory environment that can lead to ear infections like chronic otitis externa.

  • Scratching: Whether inadvertently with a nail or finger or intentionally with objects like cotton buds, scratching can cause damage and infect the ear. Scratching at wet skin can cause more significant damage compared to scratching dry skin.


Types of Diffuse Otitis Externa

Diffuse otitis externa can manifest in different forms, each with its own characteristics and treatment considerations. Understanding these types is crucial for accurate diagnosis and effective management. Here are the types:

  1. Bacterial Otitis Externa: When the primary infection is bacterial, it is referred to as diffuse bacterial otitis externa. This type of infection commonly involves bacteria such as Pseudomonas aeruginosa.

  2. Fungal Otitis Externa (Otomycosis): Otomycosis is a fungal infection of the external ear canal, typically caused by various fungi, including Aspergillus and Candida. This condition manifests as inflammation and ear canal irritation, often accompanied by itching, discomfort, discharge, and sometimes hearing loss. It's important to note that bacterial and fungal infections often coexist.

  3. Diffuse Chronic Otitis Externa (Swimmer's Ear)Chronic otitis externa, also known as swimmer's ear, typically occurs in individuals exposed to moisture for prolonged periods, such as swimmers. The constant presence of moisture in the ear canal predisposes it to bacterial or fungal infections.

  4. Malignant Otitis Externa: Malignant otitis externa, also called skull-based osteomyelitis, is a severe and potentially life-threatening form of otitis externa. It occurs when the infection spreads beyond the ear canal's external layer, affecting adjacent ear structures. The pain associated with malignant otitis externa is intense and severe. Historically, the mortality rate was high due to limited treatment options, but advancements in surgical techniques and potent antibiotics have significantly improved patient outcomes, with around 80% survival in early-stage cases.



Diffuse Otitis Externa Symptoms

Diffuse otitis externa often occurs due to bacterial or fungal infections and can lead to various uncomfortable symptoms like:

  1. Dull aching pain or severe pain

  2. Watery discharge or pus discharge

  3. Sensation of blockage in the ear

  4. Deafness

  5. Itchiness

  6. Redness and swelling of the ear canal skin

  7. Perforation of the eardrum


Differentiating Bacterial and Fungal Otitis Externa

Recognizing the symptoms of diffuse otitis externa and understanding the visual cues that differentiate between fungal and bacterial infections are essential for effective diagnosis and tailored treatment plans. While the symptoms of diffuse otitis externa caused by fungal and bacterial infections may overlap, some key differences can help differentiate between the two.


Fungal ear infections typically manifest with noticeable itchiness, setting them apart from bacterial infections. While mild irritation may occur upon water exposure or dryness in the skin, intense itchiness is a key indicator of fungal involvement. Additionally, signs such as redness and swelling of the ear canal skin, presence of pus or fluids in the ear, and the appearance of either whitish curd-like material (suggestive of Candida infection) or black and white dots-like material (suggestive of Aspergillus Niger infection) are indicative of fungal infection.


Both Candida and Aspergillus infections are similarly managed when it comes to treatment. The crucial distinction lies in identifying whether the infection is fungal or bacterial. This is paramount because treating a fungal infection with antibiotics alone can exacerbate the condition, causing the fungus to proliferate rapidly. Many patients who self-medicate use antibiotic ear drops to treat ear problems. However, using the wrong medication can cause a rapid escalation of symptoms within hours, including unbearable pain and intensified itching.


It is important to note that both fungal and bacterial otitis externa can also coexist, requiring carefully tailored medication with antifungals and antibiotics apart from getting our ears cleaned.


How Can We Go Wrong with Self-Treatment?

In self-treatment, one of the biggest risks is misdiagnosis. Without proper evaluation by a healthcare professional, individuals may not accurately determine whether their otitis externa is bacterial or fungal in nature. Using antibiotic ear drops without a prescription for fungal or bacterial infection can exacerbate the condition or bring in new problems. For otomycosis (fungal otitis externa), the condition can worsen overnight, leading to pain and perforation of the ear drum. For bacterial otitis externa, overdose can kill all the bacteria in the ear canal and give a free pass for fungus to grow initiating a new infection.


Complications of untreated or improperly treated otitis externa can be severe. In cases where fungal otitis externa progresses unchecked, it can lead to permanent perforation of the eardrum. Unlike perforations caused by bacterial infections, those resulting from fungal infections tend to be more persistent and may require surgical intervention to repair.


Some assume the itchiness in the ear is due to dry skin for otomycosis conditions. They end up putting oil drops in the ear that act as food for the fungus, promoting further growth and worsening symptoms.


Diffuse Otitis Externa Treatment 

So, while treating diffuse otitis externa, understanding the underlying cause is crucial for effective management. Whether it's a bacterial or fungal infection or both dictates the treatment approach.

  1. Bacterial Otitis Externa: Treatment for bacterial ear infections typically involves oral antibiotics and local ear drops or ointments. The choice of medication and treatment duration depends on the infection's severity and individual patient factors.

  2. Fungal Otitis Externa: The treatment involves two steps- first, the fungus must be cleared from the ear canal, which is done by a thorough cleaning. Then, the ENT doctor will prescribe antifungal ear drops. However, if the infection worsens or spreads to the eardrums, more extensive measures, such as major ear surgery, may be necessary, especially if there's a risk of permanent hearing loss.

  3. Malignant Otitis Externa: Malignant otitis externa is a severe and potentially life-threatening form of the infection that extends beyond the external ear canal. Treatment typically involves aggressive management with intravenous antibiotics and surgical intervention to remove infected tissue and prevent further spread of the infection.

By adhering to appropriate treatment protocols and seeking medical guidance, patients can effectively manage diffuse otitis externa and minimize the risk of complications.



Diffuse otitis externa, if left untreated or improperly managed, can lead to various complications, particularly malignant otitis externa:

  • Spread of Infection: In severe cases, otitis externa can spread beyond the ear canal to adjacent structures, such as the temporomandibular joint, temporal bone, parotid gland, or coverings of the brain. This spread can lead to more extensive infections and potentially life-threatening conditions.

  • Perforation of the Eardrum: Prolonged diffuse otitis externa can cause a perforation of the eardrum. Perforation can cause hearing loss and increase the risk of further infections.

Early diagnosis and proper medical intervention are crucial to prevent complications and ensure effective treatment.


Preventive Measures for Diffuse Otitis Externa

While diffuse otitis externa can be painful and uncomfortable, there are steps you can take to reduce your risk of developing this condition:

  1. Prevent water from entering the ear: Avoid letting water into the ears during activities like swimming.

  2. Avoid cleaning: If water does enter the ear, avoid cleaning it, as it can damage the skin and protective layer.

  3. Avoid Inserting Objects: Refrain from inserting cotton swabs, fingers, or other objects into your ear canal, as this can damage the delicate skin and increase the risk of infection.

  4. Seek prompt treatment: If symptoms of otitis externa develop, seek medical attention promptly to prevent complications and promote faster recovery.

  5. Never use oil drops: As discussed earlier, oil can promote fungal growth. If you have dry ears, reach out to a nearby ENT who can prescribe you a safe cream to keep your ear canal healthy.

  6. Never Self-Medicate: Even an ENT cannot tell what problem he has in his ear without another ENT checking the ear with at least an otoscope or diagnostic endoscope. So, how can we diagnose and treat ourselves?


By incorporating these preventive measures into your routine, you can significantly reduce the risk of developing diffuse otitis externa and enjoy healthier ears.



In conclusion, diffuse otitis externa poses significant risks, especially when left untreated or when self-medication is attempted. Prompt diagnosis and appropriate treatment are essential for managing the condition effectively and preventing complications that could impact hearing and overall health.

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