Free-Living Pathogenic Amoeba

Question 1

Acanthamoeba

Infective stage:

Diagnostic stages:

Answer 1

trophozoite

cyst and trophozoite in tissue

Question 2

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

Answer 2

Acanthamoeba

Question 3

Acanthamoeba

Disease:

Answer 3

Acanthamoeba keratitis (AK)

Granulomatous amoebic encephalitis (GAE)

Question 4

: “thorn-like” appendages more evident under phase contrast microscopy

Answer 4

acanthopodia

Question 5

• Feed on gram-negative bacteria, blue-green algae, or yeasts

• Corneal epithelial cells and brain tissues through phagocytosis and production of lytic enzymes

Answer 5

Acanthamoeba

Question 6

Cyst

• Polygonal, spherical, or starshaped

Answer 6

Acanthamoeba

Question 7

Double

• Outer smooth irregular ectocyst

• Inner rough polyhedral endocyst with many pores (ostioles)

• Formed when conditions are not favorable

• Highly resilient cyst

Answer 7

Acanthamoeba

Question 8

• Usually fatal within 3-40 days

• Usually among immunocompromised individuals: chronically ill, debilitated, on immunosuppressive agents, chemotherapy, HIV-AIDS

1. From skin or lungs to brain via hematogenous route
2. Direct infection through the olfactory valves

Answer 8

Granulomatous Amoebic Encephalitis (GAE)

Question 9

Granulomatous Amoebic Encephalitis (GAE)

Answer 9

Acanthamoeba

Question 10

AVOID TOPICAL STEROIDS– may retard the immune response

Answer 10

Acanthamoeba

Question 11

Granulomatous Amoebic Encephalitis

• Combination of l…

• Surgery: decompressive lobectomy

Answer 11

amphotericin B, pentamidine isethionate, sulfadiazine, fluocytosine, fluconazole or itraconazole

Question 12

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)

Answer 12

Naegleria

Question 13

Naegleria

Mode of Transmission:

Answer 13

inhalation of contaminated water

Question 14

Naegleria

Disease:

Answer 14

Primary Amoebic Meningoencephalitis (PAM)

Question 15

Ameobicflagellate

Answer 15

Naegleria

Question 16

Naegleria

Free-living amoeba-fla with two vegetative forms

1.: trophozoite form

2.: swimming form

Answer 16

Amoeboid

Flagellate

Question 17

• Thermophilic living in hot spring and other warm aquatic environment

Answer 17

Naegleria

Question 18

Locomotory apparatus: Blunt lobose pseudopod, bidirectional motility

• Single large nucleus, with large dense karyosome, lacks peripheral chromatin

Answer 18

Naegleria fowleri

Question 19

Flagellate Form

• Elongated, pear-shaped

• Anteriorly-located single nucleus morphologically similar with nucleus of amoeboid form, two free flagella

Answer 19

Naegleria

Question 20

Naegleria

Definitive Diagnosis:

Answer 20

Demonstration of characteristic trophozoites in brain and CSF

Question 21

Naegleria

• Combination

Answer 21

amphotericin B
clotrimazole

Question 22

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.

Answer 22

Naegleria