Amoebic brain abscess

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  Amoebic brain abscess
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  Thermal cycler for PCR
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  Entamoeba histolytica

Amoebic Brain Abscess

An amoebic brain abscess is a rare and serious condition caused by the invasion of the brain by amoebae, which are single-celled organisms. This condition is a type of brain abscess, which is a collection of pus that develops in response to an infection or trauma.

Etiology

Amoebic brain abscesses are primarily caused by free-living amoebae, such as Naegleria fowleri, Acanthamoeba species, and Balamuthia mandrillaris. These organisms are typically found in warm freshwater environments, soil, and sometimes in inadequately chlorinated swimming pools.

• Naegleria fowleri: Often referred to as the "brain-eating amoeba," it is known to cause primary amoebic meningoencephalitis (PAM), a rapidly progressing and often fatal disease.
• Acanthamoeba species: These are more commonly associated with granulomatous amoebic encephalitis (GAE), a slower-progressing disease that can lead to brain abscess formation.
• Balamuthia mandrillaris: This amoeba can cause GAE and is known for its ability to cause severe infections in both immunocompetent and immunocompromised individuals.

Pathophysiology

The pathogenesis of amoebic brain abscess involves the entry of amoebae into the central nervous system (CNS) through the nasal passages, often after swimming in contaminated water. The amoebae then migrate along the olfactory nerves to the brain, where they cause tissue destruction and inflammation, leading to abscess formation.

Clinical Presentation

Symptoms of an amoebic brain abscess can vary depending on the causative organism and the location of the abscess. Common symptoms include:

• Severe headache
• Fever
• Nausea and vomiting
• Neurological deficits such as seizures, altered mental status, and focal neurological signs
• Neck stiffness (in cases involving meningeal irritation)

Diagnosis

Diagnosis of an amoebic brain abscess is challenging and often requires a combination of clinical suspicion, imaging studies, and laboratory tests.

• Imaging: Magnetic resonance imaging (MRI) and computed tomography (CT) scans can reveal the presence of an abscess.
• Laboratory tests: Examination of cerebrospinal fluid (CSF) obtained via lumbar puncture may show elevated white blood cell count, elevated protein, and low glucose levels. Amoebae may be identified in CSF or brain tissue samples.
• Molecular techniques: Polymerase chain reaction (PCR) assays can be used to detect amoebic DNA in clinical specimens.

Treatment

Treatment of amoebic brain abscesses involves a combination of antimicrobial therapy and supportive care. The choice of drugs depends on the specific amoeba involved:

• Naegleria fowleri: Treatment may include amphotericin B, miltefosine, and other antifungal agents.
• Acanthamoeba and Balamuthia mandrillaris: Treatment regimens often include a combination of pentamidine, sulfadiazine, flucytosine, and fluconazole.

Surgical intervention may be necessary to drain the abscess or relieve intracranial pressure.

Prognosis

The prognosis for patients with amoebic brain abscess is generally poor, especially in cases caused by Naegleria fowleri. Early diagnosis and aggressive treatment are critical for improving outcomes.

Related Pages

• Brain abscess
• Granulomatous amoebic encephalitis
• Primary amoebic meningoencephalitis
• Naegleria fowleri
• Acanthamoeba
• Balamuthia mandrillaris