CNS Module: Free Living Amoebae

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary mode of transmission for Naegleria fowleri?

Entry through the nasal mucosa (correct)

Contaminated food

Contact with infected soil

Inhalation of spores

Which of the following is NOT a clinical manifestation of primary amoebic meningoencephalitis (PAM)?

Severe abdominal pain (correct)

Fever

Sore throat

Nausea and vomiting

What are the three known morphologic forms of Naegleria fowleri?

Trophozoites, cysts, and flagellates (correct)

Amoeboid forms, spores, and hyphae

Cysts, trophozoites, and flagellates

Flagellate forms, cysts, and spores

Which of the following infections is caused by Acanthamoeba?

Granulomatous amoebic encephalitis Signup and view all the answers

Which statement about Naegleria fowleri prevalence is correct?

It exhibits higher prevalence during the summer. Signup and view all the answers

What is a common neurological symptom associated with primary amoebic meningoencephalitis?

Severe headaches Signup and view all the answers

What does Kernig’s sign indicate in the context of meningitis?

Nuchal rigidity Signup and view all the answers

What type of infections can be prevented by understanding the transmission of free living amoebae?

Infections caused by free living amoebae Signup and view all the answers

What is a diagnostic sign of meningitis observed in patients?

Inability to fully straighten the leg when the hip is flexed Signup and view all the answers

What is the preferred method for diagnosing Naegleria fowleri infection?

Microscopic examination of cerebrospinal fluid Signup and view all the answers

Which combination of medications has shown effectiveness against Naegleria fowleri infections?

Amphotericin B and rifampin Signup and view all the answers

What is one recommended preventive measure for Naegleria fowleri infections in swimming pools?

Adequate chlorination of pools Signup and view all the answers

Which group of individuals is at increased risk for direct eye invasion by Acanthamoeba species?

Contact lens wearers Signup and view all the answers

What is a common symptom of granulomatous amebic encephalitis caused by Acanthamoeba?

Slowly developing headaches Signup and view all the answers

How do Acanthamoeba species typically enter the body to cause infection?

Via nasal inhalation or aspiration Signup and view all the answers

Which of the following factors is a predisposing condition for CNS infections caused by Acanthamoeba?

Being immunocompromised Signup and view all the answers

Study Notes

Faculty of Medicine Level 3 CNS Module: Free Living Amoebae

Lecture: Free living amoebae
Professor: Gehan Salah Sadek
Date: 15/11/2022

Intended Learning Outcomes

Students will identify the transmission methods of free-living amoebae.
Students will distinguish between Naegleria fowleri and Acanthamoeba species.
Students will describe the clinical characteristics of primary amoebic meningoencephalitis (PAM), granulomatous amoebic encephalitis (GAE), and Acanthamoeba keratitis.
Students will support preventive measures for infections caused by free-living amoebae.

Free Living Amoebae

Categorized into pathogenic and non-pathogenic types.
Pathogenic free-living amoebae include Naegleria fowleri and Acanthamoeba species.
Non-pathogenic free-living amoebae (Coprozoic) are not associated with disease.

Naegleria fowleri

Exclusive ameba with three forms: ameboid trophozoites, flagellate forms, and cysts.
Characteristics of ameboid trophozoites include large karyosome and pseudopods.
Flagellate forms have flagella and characteristic size ranges.
Cysts display a double cell wall structure

Epidemiology of Naegleria fowleri

Predominantly found in warm bodies of water, including lakes, streams, and swimming pools.
Prevalence is higher in summer months.
Infection occurs through nasal inhalation of ameboid trophozoites.

Clinical Picture: Naegleria fowleri

Asymptomatic: Nasal colonization is common but asymptomatic.
Primary amoebic meningoencephalitis (PAM): Characterized by rapid tissue destruction in the brain. Initial manifestations include fever, headache, sore throat, nausea, and vomiting, followed by meningitis symptoms like stiff neck and seizures.

Acanthamoeba species

Common disease: granulomatous amebic encephalitis (GAE), Acanthamoeba keratitis
Common associated characteristics: pseudopods and large karyosome. Trophozoites and cysts.

Mode of Transmission: Acanthamoeba species

CNS infection: Aspiration/inhalation via lower respiratory tract.
Eye infection (keratitis): Direct invasion, common in contact lens wearers and those with corneal trauma.

Clinical Picture: Acanthamoeba species

CNS infection: Symptoms develop slowly, including headaches, seizures, neck stiffness, nausea, and vomiting. Lesions of the brain often contain trophozoites and cysts.
Infections may spread to other parts of the body like kidneys, pancreas, prostate, and uterus.

Diagnosis

**Naegleria fowleri: Cerebrospinal fluid (CSF) examination, saline and iodine wet mounts.
Acanthamoeba: CSF examination.

Treatment

Naegleria fowleri: Prompt, aggressive treatment with amphotericin B, sometimes combined with rifampin or miconazole, is crucial. Survival is rare without swift intervention.
Acanthamoeba: Sulfamethazine has shown potential; however, treatment challenges exist due to delayed recognition of the infection.

Prevention and Control

Health education regarding water safety, particularly for warm bodies of water.
Adequate chlorination of swimming pools and hot tubs.
Prompt repair of cracks in pools, tubs, and baths to eliminate potential contamination sources.

Kernig's Sign

A diagnostic sign for meningitis.
Inability to fully straighten the leg when the hip is flexed and 90 degrees, due to hamstring stiffness.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz focuses on the CNS module related to free living amoebae, particularly identifying transmission methods and differentiating between Naegleria fowleri and Acanthamoeba. It also covers clinical characteristics of infections caused by these amoebae and preventive measures. Perfect for Level 3 Faculty of Medicine students.