Free-living Amoebae

They are amoebae that normally inhabit:- Water (lakes, swimming pools, air-conditioning units)- Moist soil.- Decaying vegetations.

Potentially Pathogenic Free-living amoebae

Amoeboid form

Trophozoite form

Naegleria fowleri Acanthamoeba species

In water

Flagellate form

Cyst form Cyst form

Trophozoite

In water or air

Dr. RAAFAT MOHAMED

I- Naegleria fowleri(Acute primary amoebic Meningoencephalitis)

• Geographical Distribution: some parts of the world.

• Mode of infection:

- Swimming and sniffing (inhalation) in contaminated water.

إستنشاق

Diffuse meningoencephalitis

Dr. RAAFAT MOHAMED

Pathogenesis and Clinical Picture

Amoeboid trophozoite

Nasal mucosa

Cribriform plate

Olfactory nerve

Brain, meninges

Diffuse meningoencephalitis with haemorrhage and necrosis of brain tissue

Fever, headache, nausea, vomiting, stiffness of neck, convulsions.

Disturbance in the sense of smell and taste

Coma and death within 3-6 days from infection

Thus Naegleria causes acute fulminant rapidly fatal

disease Dr. RAAFAT MOHAMED

Dr. RAAFAT MOHAMED

Dr. RAAFAT MOHAMED

brain sectionin vitro culture

Acanthamoeba species

Granulomatous Amoebic Encephalitis

Acanthamoeba Keratitis

Mode of infection

Nose to Lower respiratory tract to Blood to Brain

Ulcerated skin and mucosa to Blood to Brain

Through corneal traumaExposure to contaminated waterWearing contaminated contact lenses

Dr. RAAFAT MOHAMED

Dr. RAAFAT MOHAMED

Cyst

Trophozoite

Dr. RAAFAT MOHAMED

Pathogenesis and Clinical Picture

Acanthamoeba causes single or multiple focal granulomatous space-occupying lesions

in the brain.

- Headache, nausea, vomiting, convulsions, stiffness of the neck and altered mental state.

- Sub-acute or chronic course lasting for weeks to months or years.

- In AIDS patients, the disease may be fulminating resembling infection with Naegleria

Dr. RAAFAT MOHAMED

• Diffuse meningoencephalitis.

• Runs rapidly fatal course (death within 3-6 days)

• History of swimming in natural water or swimming pools.

• Infection occurs through: The nasal route

cribriform plate olfactory nerve brain.

• Focal, granulomatous, space-occupying lesion.

• Runs sub-acute or chronic course (lasts for weeks, months or years)

• Not strongly associated with swimming.

• Infection occurs in: Lower respiratory tract,

ulcerated skin or mucosa blood stream CNS

Naegleria meningoencephalitis

Acanthamoeba encephalitis

Children & young adults

Debilitated Chronically ill low immunity

Dr. RAAFAT MOHAMED

Diagnosis

• History of swimming in natural water or in swimming pools within the preceding days.

• C.S.F. examination:

- Microscopy.

- Suspension in fresh water.

- Culture.

• C.S.F. examination

Naegleria Acanthamoeba

Dr. RAAFAT MOHAMED

Treatment

No complete satisfactory treatment

Naegleria Acanthamoeba

Amphotericin BExcision of the focal lesion

+ ketoconazol

Penicillin and chloramphenicol

Epidemiology and Control of Naegleria

Water and air are sources of infection

Avoidance of swimming in contaminated water

Proper chlorination of water

(I.V. or I. thecal)

Dr. RAAFAT MOHAMED

Acanthamoeba keratitis

Pathogenesis and Clinical picture:

Chronic progressive ulcerative keratitis perforation

In AIDS patients, the infection may cause endophthalmitis.

Severe ocular pain and affection of vision.

Dr. RAAFAT MOHAMED

Diagnosis

Identification of trophozoites and cysts in corneal scraping:

- Directly- After culture

Treatment

Oral itraconazole + topical miconazole Corneal transplant

Epidemiology and Control

Wearing of contact lenses especially while swimming

Inappropriate care of lenses

The use of home-made saline for cleaning lenses Dr. RAAFAT MOHAMED