Free-Living Pathogenic Amoeba Flashcards
Acanthamoeba
Infective stage:
Diagnostic stages:
trophozoite
cyst and trophozoite in tissue
Found in lakes, swimming pools, tap water, heating and air conditioning units, sewage, dental treatment units, dialysis machines, even survive in contact lens cleaning solutions
Acanthamoeba
Acanthamoeba
Disease:
Acanthamoeba keratitis (AK)
Granulomatous amoebic encephalitis (GAE)
: “thorn-like” appendages more evident under phase contrast microscopy
acanthopodia
• Feed on gram-negative bacteria, blue-green algae, or yeasts
• Corneal epithelial cells and brain tissues through phagocytosis and production of lytic enzymes
Acanthamoeba
Cyst
• Polygonal, spherical, or starshaped
Acanthamoeba
Double
• Outer smooth irregular ectocyst
• Inner rough polyhedral endocyst with many pores (ostioles)
• Formed when conditions are not favorable
• Highly resilient cyst
Acanthamoeba
• Usually fatal within 3-40 days
• Usually among immunocompromised individuals: chronically ill, debilitated, on immunosuppressive agents, chemotherapy, HIV-AIDS
- From skin or lungs to brain via hematogenous route
- Direct infection through the olfactory valves
Granulomatous Amoebic Encephalitis (GAE)
Granulomatous Amoebic Encephalitis (GAE)
Acanthamoeba
AVOID TOPICAL STEROIDS– may retard the immune response
Acanthamoeba
Granulomatous Amoebic Encephalitis
• Combination of l…
• Surgery: decompressive lobectomy
amphotericin B, pentamidine isethionate, sulfadiazine, fluocytosine, fluconazole or itraconazole
Usual Exposure: history of swimming in freshwater lakes or ponds or swimming pools
• (Trophozoite penetrates nasal mucosa and migrate to the brain via olfactory nerves)
Naegleria
Naegleria
Mode of Transmission:
inhalation of contaminated water
Naegleria
Disease:
Primary Amoebic Meningoencephalitis (PAM)
Ameobicflagellate
Naegleria
Naegleria
Free-living amoeba-fla with two vegetative forms
1.: trophozoite form
2.: swimming form
Amoeboid
Flagellate
• Thermophilic living in hot spring and other warm aquatic environment
Naegleria
Locomotory apparatus: Blunt lobose pseudopod, bidirectional motility
• Single large nucleus, with large dense karyosome, lacks peripheral chromatin
Naegleria fowleri
Flagellate Form
• Elongated, pear-shaped
• Anteriorly-located single nucleus morphologically similar with nucleus of amoeboid form, two free flagella
Naegleria
Naegleria
Definitive Diagnosis:
Demonstration of characteristic trophozoites in brain and CSF
Naegleria
• Combination
amphotericin B
clotrimazole
Prevention and Control
• Avoidance of immersion of the head and accidental inhalation of water should be practiced in endemic areas and in hot springs.
• Chlorination of water at 1ppm or higher.
Naegleria
