Protozoa (Free-living Amoeba & Ciliates) Flashcards by Lyka L. Laude

What are the free-living amoeba?

Acanthamoeba

Naegleria

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Causative agent of Primary Amoebic Meningoencephalitis (PAM)

Naegleria fowleri

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Small free-living amoeba characterized by an active trophozoite stage and dormant cystic stage.

Acanthamoeba

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The causative agent of Granulomatous Amebic Encephalitis (GAE).

Acanthamoeba

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Free-living amoebo-flagellates.

Naegleria

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What is an amoebo-flagellate?

Trophozoite can transform into nonreproductive flagellate stage or a resistant cyst.

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Naegleria that is nonpathogenic.

Naegleria gruberi

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Naegleria that is pathogenic that may cause menigoencephalitis in man.

Naegleria fowleri

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What are the symptoms in Naegleria fowleri infection?

Headache
Fever
Neck rigidity
Mental confusion

May lead to coma and death

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Free-living amoeba that after entering the nose and nasal cavities, the trophozoites will migrate along the olfactory nerves, through the cribriform plate and into the cranium.

N. fowleri

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This unique stage transformation allows N. fowleri to move toward food sources more rapidly.

The ability of Naegleria fowleri to transform from an ameba into flagellated organisms.

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The trophozoite form of Naegleria.

Ameba

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The swimming form of Naegleria.

Flagellate

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How many hours or days does the transformation from ameba to flagellate of Naegleria?

2-3 hrs or up to 3-4 days

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True or False: The trophozoite stage of Naegleria is readily forms a pair of flagella originating from the tip of a pear-shaped body.

True

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Naegleria that is locally isolated in the Philippines in thermally-polluted streams, an artificially-heated swimming pool, and from a brain aspirate of a young patient

Naegleria philippinensis

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How does PAM be diagnosed?

Actual appearance of trophozoites in the brain and cerebrospinal fluid.

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Deadly free-living amoeba

Naegleria fowleri

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A 12 year old female is brought to the emergency room with MENINGITIS and a history of swimming in a warm water spring. Motile amoeba is seen in CSF and are most likely:

a. Iodamoeba butschlii
b. Endolimax nana
c. Dientamoeba fragilis
d. Naegleria fowleri

d. Naegleria fowleri

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Free-living amoeba that the trophozoites had a blunt, lobose pseudopodia and directional motility.

N. fowleri

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What are the specific test for N. fowleri?

PCR and ELISA

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Drug of choice of Primary Amebic Meningoencephalitis

Polytene antibiotic Amphotericin B

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True or False: There is no known means of prevention and control of Naegleria infection

True

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Treatment that inhibits the growth of N. fowleri when used at high concentration of 25 -50 ug/ml. and also prevents enflagellation and encystment of ameba.

Tetrahydrocannabinol

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Lethal to N. fowleri trophozoites

Drying

It can be a successful therapy to PAM

Azithromycin

Epidemiology of Naegleria

Chlorinated swimming poos, freshwater lakes, Thermal springs, domestic water supplies, Thermally polluted water, sewage, soil, air, humidifier systems, cell cultures, and human throat and nasal cavities Soil

Infective stage of N. fowleri

Trophozoite

Diagnostic stage of N. fowleri

Trophozoite

Since there is no known means of prevention and control of Naegleria infection, could you think of way to avoid the infection?

Anything is acceptable. To decrease the possibility of infection, one should avoid diving into and swimming in warm and stagnant freshwater pools, water discharge pools, unchlorinated poorly maintained swimming poolsm or mud-lined lake and ponds.

Mode of transmission of Naegleria fowleri

When water containing the ameba enters the body through the nose

True or False: N. fowleri has two stages, cysts and trophozoites, in its life cycle.

False. N. fowleri has three stages: 1. cysts, 2. trophozoites 3. flagellated forms

True or False: N. fowleri trophozoites are found in cerebrospinal fluid (CSF) and tissue.

True

True or False: Flagellated forms are found in CSF.

True

What is the mall, spiny filaments for locomotion that has sluggish and polydirectional movement of Acanthamoeba trophozoites?

Acanthopodia

Free-living pathogenic amoeba that may be axenically cultivated in PYGC medium (proteose-peptone, yeast extract, glucose and cysteine)

Acanthamoeba

It considered to be an important diagnostic feature of the GAE.

Skin lesions

Free-living amoeba that its cyst has double walled with outer wrinked wall.

Acanthamoeba spp.

Acanthos means _______.

Thorn or spiny

Route of invasion and penetration of Acanthamoeba.

CNS via the circulatory system

The primary site of infections are either _________ or _________ of Acanthamoeba.

Skin or lungs

A rare corneal infection with Acanthamoeba species, typically occurring in contact lens wearers.

Amebic keratitis

Most of the contact lens wearer got infected by Acanthamoeba because they use ____________.

Home-made saline

True or False: Enlarged corneal nerve (keratoneuritis) is the cardinal pathognomonic of Acanthamoeba keratitis.

True

Infective stage of Acanthamoeba

Trophozoites

Diagnostic stage of Acanthamoeba

Cysts and Trophozoites

Mode of Transmission of Acanthamoeba spp.

1. Through the eye (contact lens) 2. Through nasal passages (inhalation) to the lower respiratory tract 3. Through ulcerated or broken skin

Epidemiology of Acanthamoeba

Worldwide Specifics: Isolated from freshwater, seawater, ocean sediments, frozen swimming water, distribution water, bottled mineral water, industrial cooling water, air conditioners, air, seawage, soil, compost, chlorinated swimming pools, medical pools, dental treatment units, gastric-lavage tubing, dialysis units, contact lenses.

Acanthamoeba can be found in _______ and ________.

Water and soil

Definitive host of Acanthamoeba

Human

Diagnosis of Acanthamoeba spp.

- Is made only after death in majority of cases. - Specific diagnosis depend on the demonstration of trophozoite or cysts in tissues using histopathologic stains and microscopy. - Acanthamoeba keratitis can be diagnosed by epithelial biopsy for histologic analysis and isolation of the organism from lens of contact lens wearers. - Polymerase Chain Reactions

Etiologic agents of Acanthamoeba

``` Acanthamoeba castelloni, Acanthamoeba culbertsoni, Acanthamoeba hutchetti, Acanthamoeba polyphaga, Acanthamoeba rhysoides ```

Treatment of cerebral manifestation (Acanthamoeba encephalitis)

``` 5-Fluorocytosine Ketoconazole Itraconazole Pentamidine Amphotericin B ```

Treatment of Acanthamoeba keratitis

- surgical excision of the infected cornea and corneal transplantation, Therapeutic keratoplasty - Clotrimazole in combination with pentamidine, isethionate and Neospirin - Deep laminar keratectomy with conjunctival flap secured with interrupted-10-0 nylon sutures has been used successfully.

Prevention and controls of Acanthamoeba

- There is hardly any means of preventing possible exposure although boiling of water is the best possible way of killing the trophozoites and cyst. - Contact lens wears should regularly clean their lenses - When cleaning, mask should be worn since cyst can be carried by dust.

An ubiquitous organism which has been isolated from air, aquaria, bottled mineral water,soil, swimming pools, deep well water, contact lens cleaning solutions, and various other sources.

Acanthamoeba

It is the preferred habitat of free-living amebae providing source of oxygen, water, temperatures compatible with survival and a bacterial food supply.

Soil

Largest intestinal protozoa

Balantidium coli

Only pathogenic ciliates -it elaborates hyaluronidase.

Balantidium coli

Causative agent of Balantidial dysentery

Balantidium coli

Mode of transmission of Balantidium coli

Ingestion of cyst from contaminated food or water

Epidemiology of Balantidium coli in the Philippines

Sporadic

True or False: Prevalence of Balantidial dysentery is associated with poor environmental sanitation.

True

Reservoir host of Balantidium coli

Pig

Infective stage of Balantidium coli

Cyst

Diagnostic stage of Balantidium coli

Cysts

Since Balantidium coli is the largest intestinal protozoan, what is its size?

30-300 um long by 30-100 um wide

What is the organ of locomotion of Balantidium coli?

Cilia

Its trophozoite has a large bean-shaped or kidney shaped macronucleus and spherical micronucleus.

B. coli

Motility of Balantidium coli

Directional in rolling motion

Only ciliated protozoa of medical importance.

B. coli

Diagnosis of B. coli

Microscopic demonstration of trophozoite and cyst in feces Direct Fecal Smear; Concentration Tech. and Rectal biopsy

What is the use of cytostome? Does Balatidium coli cysts have cystostome?

Cytostome –structure for procurement and ingestion of food. No. Only B. coli troph has cytostome.

What is the use of cytophyge? Does Balantidium coli cysts do not have cytophyge?

Cytophyge –structure for discharge of metabolic waste Yes. B. coli cysts do not have cytophyge.

Treatment of B. coli infection

Tetracycline 500 mg | Metronidazole 750 mg

Prevention and Control of B. coli infection

Proper sanitation Safe water supply Protection of food from contamination

What is the clinical manifestation of B. coli due to its lytic enzyme hyaluronidase?

Ulceration