Amoeba Flashcards
What are protozoa?
Unicellular organisms and independent. The lowest form of animal life. Pathogenic and non-pathogenic.
What does the word ‘amoeba’ derive from?
The Greek word ‘amoibe’, which means change.
What are the two forms of amoeba based on environmental factors?
Cysts and trophozoites.
What type of locomotion organelle do amoebas possess?
Pseudopods.
Which classifications according to habitat are there for amoebae?
- Intestinal amoebae
- Free-living amoebae
What is the function of the nucleus in protozoa?
Contains chromosomes essential for life, reproduction, and genetic transmission.
What is a karyosome?
An aggregate mass inside the nucleus.
What are the two types of nuclei found in protozoa?
- Vesicular nucleus
- Compact nucleus
What does the cytoplasm in protozoa contain?
Organelles.
What are the two proportions of cytoplasm?
- Endoplasm
- Ectoplasm
What is found in the endoplasm?
Mitochondria, Golgi, ER, microsomes, stored food.
What is the function of ectoplasm?
Aids in locomotion, food acquisition, respiration, excretion, and protection.
What are pseudopodia?
Temporary, finger-like projections in amoebas for movement and food acquisition.
What type of locomotion organelle is found in zoomastigiphora?
Flagella.
What is the axoneme?
The internal portion attached to the kinetoplast in flagella.
What are cilia?
Numerous short projections in ciliophora, arising from basal granules in the ectoplasm covering the parasite’s body.
What is the feeding stage of amoebas called?
Trophozoite
Trophozoite is the active, vegetative stage where amoebas feed and grow.
What type of reproduction occurs in the trophozoite stage?
Asexual
Trophozoites reproduce asexually, allowing for rapid population increase.
What structure do trophozoites use for movement?
Pseudopods
Pseudopods are temporary projections that help amoebas move and capture food.
What is the characteristic of the cyst stage of amoebas?
Non-feeding stage
Cysts are dormant and do not feed, preparing the organism for survival in harsh conditions.
What type of reproduction occurs in the cyst stage?
Sexual
Cysts can undergo sexual reproduction, leading to genetic variation.
What is the purpose of the thick cell wall in cysts?
Protective function
The thick cell wall protects the cyst from environmental stresses and allows for dormancy.
What process transforms trophozoites into cysts?
Encystation
Encystation allows amoebas to survive unfavorable conditions by forming cysts.
Name one trigger for encystation.
Food scarcity
Other triggers include accumulation of metabolic waste, significant pH changes, and loss of water.
What is protective encystation?
No morphological changes, primarily for survival
Example: B. coli undergoes protective encystation to withstand adverse conditions.
What is reproductive encystation?
Nucleus multiplies within the cyst
This leads to multiple daughter organisms upon excystation, as seen in E. histolytica.
What process describes the transition from cysts back to trophozoites?
Excystation
Excystation is crucial for the reactivation of the amoeba in a suitable environment.
Name a trigger for excystation.
Osmotic changes in the environment
Other triggers include enzymatic action on the inner cyst wall and favorable pH.
What are standard procedures for detecting amoebas?
Direct saline wet preparations, direct iodine wet preparations, permanent slides
These methods help visualize motile trophozoites and enhance protozoan cysts.
What is the invasive stage of amoebas?
Trophozoite
Trophozoites can invade host tissues and cause infections.
Fill in the blank: Cysts are in a _______ stage.
Dormant
Dormancy allows cysts to survive until conditions are favorable for excystation.
True or False: Trophozoites have a thick cell wall.
False
Trophozoites are delicate and do not have a thick protective cell wall like cysts.
What is the subphylum of Entamoeba histolytica?
Sarcodina
What are the diseases and conditions associated with Entamoeba histolytica?
- Intestinal amebiasis
- Amoebic colitis
- Amebic dysentery
- Extra-intestinal amebiasis
- Amebic liver abscess (ALA - Most common disease)
How is Entamoeba histolytica transmitted?
Ingestion of mature infective cyst
What is the habitat of Entamoeba histolytica?
Large intestine
What is unique about Entamoeba histolytica among amoebas?
The only pathogenic amoeba
What is the structure of the trophozoite of Entamoeba histolytica?
Finger-like appearance
How many nuclei can be found in the trophozoite of Entamoeba histolytica?
1
Describe the karyosome of the trophozoite of Entamoeba histolytica.
Small and central
What cystoplasmic inclusions are found in the trophozoite of Entamoeba histolytica?
Ingested red blood cells
How many nuclei can be found in the cyst of Entamoeba histolytica?
1-4
Describe the structure of the cyst of Entamoeba histolytica.
Chromatoidal body; Cigar shaped
What cystoplasmic inclusions are found in the cyst of Entamoeba histolytica?
Chromatoid bars
What are the two types of endocytosis exhibited by Entamoeba histolytica?
- Phagocytosis - solid
- Pinocytosis - dissolved material
What is the main difference in the life cycle of Entamoeba histolytica?
Each cyst produces 4 daughter organisms called “metacystic trophozoites”
What are the prevention and control measures for Entamoeba histolytica?
- Provision of adequate, clean, and safe drinking water
- Proper disposal of human wastes with the use of sanitary toilets
- Control of insects such as flies and cockroaches
- Prevent and educate farmers on the use of human excreta as “night soils”
- Regular screening of food-handlers
- Prompt treatment of infected individuals and public education
What is the scientific name of the organism discussed?
Entamoeba hartmanni
To which subphylum does Entamoeba hartmanni belong?
Sarcodina
What class is Entamoeba hartmanni categorized under?
Lobosea
Name one disease caused by Entamoeba hartmanni.
Intestinal amebiasis
Other diseases include amoebic colitis, amebic dysentery, and extra-intestinal amebiasis.
What is the mode of transmission for Entamoeba hartmanni?
Ingestion of mature infective cyst
In which habitat can Entamoeba hartmanni typically be found?
Large intestine
Is Entamoeba hartmanni a commensal or pathogenic organism?
Commensal amoeba
How many nuclei does the trophozoite of Entamoeba hartmanni have?
1
Describe the karyosome of the trophozoite in Entamoeba hartmanni.
Small and central
What may be present as cystoplasmic inclusions in the trophozoite of Entamoeba hartmanni?
Ingested bacteria may be present
How many nuclei can be found in the cyst of Entamoeba hartmanni?
1-4
What is the karyosome like in the cyst of Entamoeba hartmanni?
Small and central
List one type of cystoplasmic inclusion found in the cyst of Entamoeba hartmanni.
Chromatoid bars
Diffuse glycogen mass is present in young cysts.
What is the subphylum classification of Entamoeba coli?
Sarcodina
What class does Entamoeba coli belong to?
Lobosea
Name a disease caused by Entamoeba coli.
Intestinal amebiasis
Other diseases include amoebic colitis, amebic dysentery, and extra-intestinal amebiasis.
What is the mode of transmission for Entamoeba coli?
Ingestion of mature infective cyst
Where does Entamoeba coli primarily inhabit?
Large intestine
What type of amoeba is Entamoeba coli?
Commensal amoeba
How many nuclei does a trophozoite of Entamoeba coli have?
1
Describe the karyosome of Entamoeba coli’s trophozoite.
Large, irregular shape, eccentric
What can often be seen in the cystoplasmic inclusions of a trophozoite?
Vacuoles containing bacteria
How many nuclei can be found in the cyst of Entamoeba coli?
1-4
What is the karyosome shape in the cyst of Entamoeba coli?
Large, irregular shape, eccentric
What are the cystoplasmic inclusions found in the cyst of Entamoeba coli?
Chromatoid bars; Diffuse glycogen mass present in young cysts
What is the scientific name of the organism discussed?
Entamoeba polecki
This organism is classified under the subphylum Sarcodina.
To which class does Entamoeba polecki belong?
Lobosea
This classification is based on its morphological characteristics.
What is the primary mode of transmission for Entamoeba polecki?
Ingestion of mature infective cyst
This mode of transmission is significant for understanding infection routes.
What type of habitat does Entamoeba polecki primarily occupy?
Large intestine
This habitat is crucial for its life cycle and development.
Is Entamoeba polecki considered a pathogen in humans?
Nonpathogen
Infections in humans are relatively rare.
What is the life cycle of Entamoeba polecki similar to?
Entamoeba histolytica
Understanding this similarity can help in studying both organisms.
What is the treatment for Entamoeba polecki infections?
Combination of metronidazole (Flagyl) and diloxanide furoate (furamide)
This treatment approach is effective for managing infections.
How many nuclei does the trophozoite of Entamoeba polecki have?
1
This characteristic is important for microscopic identification.
What is the karyosome of the trophozoite described as?
Small and central
This feature aids in the identification of the organism.
What type of inclusions are found in the trophozoite of Entamoeba polecki?
Ingested bacteria; Other food particles
These inclusions can indicate the feeding habits of the organism.
How many nuclei does the cyst of Entamoeba polecki have?
1
This characteristic is consistent with the trophozoite stage.
What is the karyosome of the cyst described as?
Small and central
This similarity to the trophozoite’s karyosome is notable.
What cystoplasmic inclusions are present in the cyst of Entamoeba polecki?
Chromatoid bars; Diffuse glycogen mass present in young cysts
These inclusions can help differentiate between stages of the organism.
What is the habitat of Endolimax nana?
Cecum of humans
Endolimax nana primarily resides in the cecum, which is part of the large intestine.
How is Endolimax nana transmitted?
Fecal-oral (contaminated food/water)
Transmission occurs when food or water contaminated with feces is ingested.
What is the size range of the trophozoite form of Endolimax nana?
6-15 micrometers
The trophozoite is the active, motile form of the organism.
Describe the nucleus of the trophozoite of Endolimax nana.
Uninucleated with an irregular karyosome
The nucleus is single and has an irregularly shaped central body.
What type of motility is observed in the trophozoite of Endolimax nana?
“Slug-like” motility
This refers to the slow, gliding movement characteristic of this organism.
What is the size range of the cyst form of Endolimax nana?
5-10 micrometers
Cysts are the dormant, resistant form of the organism.
How many nuclei can be found in the cyst of Endolimax nana?
1-4 nuclei
Cysts can contain multiple nuclei, which can be used to identify the organism.
What unique shape is associated with the nucleus of the cyst of Endolimax nana?
“Cross-eye” or “punched out” nucleus
This distinctive appearance aids in microscopic identification.
What type of chromatoidal bodies do cysts of Endolimax nana have?
Comma-shaped chromatoidal bodies
These bodies are indicative of the cyst’s structure.
What is the appearance of the cytoplasm in the cyst of Endolimax nana?
“Ground-glass” cytoplasm
This term describes the translucent and granular appearance of the cyst’s cytoplasm.
What is the clinical importance of Endolimax nana?
Non-pathogenic
Endolimax nana does not cause disease and is often found in healthy individuals.
In which areas is Endolimax nana often found?
Areas where E.coli is present
The presence of E.coli is often associated with the same environments where Endolimax nana is found.
What is the habitat of Iodamoeba bütschlii?
Cecum of humans, more common in warm climates
Iodamoeba bütschlii is typically found in the cecum, which is part of the large intestine.
How is Iodamoeba bütschlii transmitted?
Fecal-oral (contaminated food/water)
Transmission occurs when individuals ingest contaminated food or water.
What are the key characteristics of the trophozoite form of Iodamoeba bütschlii?
- 6-15 micrometers
- Single nucleus
- Large karyosome
- Perikaryosomal central chromatin granules
- Pink glycogen mass (1/2 or 1/3 of cell size)
The trophozoite is the active, feeding stage of the organism.
What are the key characteristics of the cyst form of Iodamoeba bütschlii?
- 6-15 micrometers
- Single nucleus
- Large glycogen mass (more than 1/2 or 2/3 of the cell)
- Stains mahogany-brown with Lugol’s iodine
The cyst form is a dormant stage that can survive outside the host.
Is Iodamoeba bütschlii pathogenic?
Non-pathogenic but may be mistaken for pathogenic amoebas in fecal samples
While Iodamoeba bütschlii itself does not cause disease, it can be confused with harmful amoebas during diagnostics.
What is the habitat of Entamoeba gingivalis?
Oral cavity, including gums, tonsillar crypts, and pyorrhea pockets
Entamoeba gingivalis is specifically associated with areas of the mouth that may be affected by poor hygiene.
How is Entamoeba gingivalis transmitted?
Direct contact, such as kissing, shared utensils, or droplet spray
This mode of transmission highlights the communicable nature of the organism.
What is the only morphologic structure of Entamoeba gingivalis?
Trophozoite
Trophozoites are the active, feeding stage of the organism.
What is the size range of Entamoeba gingivalis trophozoites?
5-15 micrometers
This size range is important for microscopic identification.
What is a distinguishing feature of Entamoeba gingivalis?
Ingests leukocytes
This characteristic helps differentiate it from other amoebas.
Does Entamoeba gingivalis form cysts?
No
The absence of a cyst form differentiates it from many other protozoan parasites.
Is Entamoeba gingivalis pathogenic?
Non-pathogenic
It is associated with poor oral hygiene but does not cause disease.
With which organisms is Entamoeba gingivalis often found?
Trichomonas tenax and Candida albicans
These organisms are also associated with oral conditions.
What is the transmission route for Endolimax nana and Iodamoeba bütschlii?
Fecal-oral transmission
These organisms are intestinal commensals and differ from Entamoeba gingivalis.
What is a common confusion during microscopic examination involving Entamoeba gingivalis?
May be confused with harmful parasites
This confusion highlights the importance of accurate identification in laboratory settings.
What is the habitat of Naegleria fowleri?
Fresh-water and moist soil
Naegleria fowleri thrives in warm freshwater environments, such as lakes and hot springs.
How is Naegleria fowleri transmitted?
Instillation of trophozoites through the nose
This typically occurs when swimming in contaminated water.
What is the size range of the trophozoite form of Naegleria fowleri?
8-22 micrometers
Trophozoites are the active, feeding form of the amoeba.
Describe the morphology of Naegleria fowleri trophozoites.
Elongate with a broad anterior and tapered posterior; slug-like motility with blunt pseudopodia
These features aid in movement and feeding.
What are the characteristics of Naegleria fowleri cysts?
Round (9-12 micrometers), thick-walled, single nucleus with granular cytoplasm
Cysts are a dormant form that can survive in harsh conditions.
What disease does Naegleria fowleri cause?
Primary Amoebic Meningoencephalitis (PAM)
PAM is a rapidly fatal brain infection.
What are the symptoms of Primary Amoebic Meningoencephalitis (PAM)?
- Headache
- Fever
- Stiff neck
- Coma (Kernig’s sign)
Symptoms typically appear within days after infection.
What is the typical time frame for death after PAM onset?
3-6 days
Rapid intervention is crucial for survival.
What is the key to survival in cases of PAM?
Early diagnosis
There is no effective treatment for PAM.
What are the three morphologic forms of Naegleria fowleri?
- Amoeboid trophozoites
- Flagellate form
- Cysts
Each form has distinct characteristics and roles in the life cycle.
What are some prevention methods for Naegleria fowleri infections?
- Avoid contact with stagnant or thermal waters
- Adequate chlorination of public water supplies
- Salination of public pools up to 0.7%
- Public education on water safety
These measures can significantly reduce the risk of infection.
What form of Naegleria fowleri is found in humans?
Ameboid trophozoites
This form is responsible for causing disease in humans.
How do trophozoites replicate in the human body?
By binary fission
This asexual reproduction allows rapid population growth.
What happens to flagellate trophozoites when transferred to water?
They form in vitro but do not divide
They can convert back into ameboid trophozoites to resume reproduction.
What is the entry point for Naegleria fowleri to infect humans?
Nasal mucosa
The amoeba migrates to the brain, leading to rapid tissue destruction.
What other disease is caused by a different amoeba that can enter through the skin or eyes?
Granulomatous Amoebic Meningoencephalitis (GAE)
GAE is a chronic brain infection caused by Acanthamoeba.
What are the symptoms of Granulomatous Amoebic Meningoencephalitis (GAE)?
- Headache
- Seizures
- Altered mental status
- Necrosis
GAE progresses slowly compared to PAM.
What eye infection is associated with Acanthamoeba?
Acanthamoeba keratitis
This infection is often linked to contact lens use.
What is a prevention measure for Acanthamoeba keratitis?
Proper contact lens hygiene
This includes cleaning and storing lenses correctly.
True or False: There is a definitive drug for granulomatous amoebic encephalitis.
False
Treatment options are limited and primarily supportive.
What is the size of the trophozoite of Acanthamoeba culbrtsoni?
30 micrometers
Trophozoites are the active, feeding stage of the organism.
What distinguishes the nucleus of the trophozoite of Acanthamoeba culbrtsoni?
Prominent; nucleus with a large nucleolus
The nucleolus is a region within the nucleus involved in ribosome production.
What is the size of the cyst of Acanthamoeba culbrtsoni?
20+ micrometers
Cysts are the dormant, resistant stage of the organism.
Describe the structure of the cyst of Acanthamoeba culbrtsoni.
Double-walled with polyhedral inner endocyst and smooth/slightly wrinkled outer ectocyst
The double-walled structure provides protection against environmental stress.
Where is the nucleus located in the cyst of Acanthamoeba culbrtsoni?
Centrally located nucleus with a large karyosome
The karyosome is a mass of chromatin within the nucleus.
What is Acanthamoeba polyphaga?
Acanthamoeba polyphaga is a species of free-living amoeba.
What is the size of the trophozoite of Acanthamoeba polyphaga?
23 micrometers
What type of pseudopodia does the trophozoite of Acanthamoeba polyphaga have?
Broad hyaline lobopodia
What is a prominent feature of the trophozoite of Acanthamoeba polyphaga?
Prominent uroid process
How many contractile vacuoles does the trophozoite of Acanthamoeba polyphaga possess?
Single contractile vacuole
What type of nucleus does the trophozoite of Acanthamoeba polyphaga have?
Vesicular nucleus with centrally located endosome
What are the characteristics of the cyst of Acanthamoeba polyphaga?
Double-walled, polyhedral or stellate endocysts, wrinkled ectocyst
What is the shape of the trophozoite of Acanthamoeba costelani?
Elongated shape
Trophozoites are the active feeding form of the organism.
What is the size of the cyst of Acanthamoeba costelani?
16 micrometers
Cysts are the dormant, resistant form of the organism.
What is the shape of the cyst of Acanthamoeba costelani?
Polyhedral
Polyhedral refers to a shape with many faces, typical for cysts.
Describe the ectocysts of Acanthamoeba costelani cysts.
Rippled or wrinkled
The ectocyst is the outer layer of the cyst, which provides protection.
What is the length range of the trophozoite of Acanthamoeba astronyxis?
25-60 micrometers
What are conspicuous features of the trophozoite of Acanthamoeba astronyxis?
Conspicuous food vacuoles and endoplasm containing small-yellowish refractile bodies
What is the shape of the cyst of Acanthamoeba astronyxis?
Biconcave cyst
What are the characteristics of the ectocyts in Acanthamoeba astronyxis cyst?
Folded ectocyts
What type of endocyst does Acanthamoeba astronyxis have?
Stellate endocysts
What is the size range of the cyst of Acanthamoeba astronyxis?
14-25 micrometers
How many prominent nuclei does the cyst of Acanthamoeba astronyxis have?
Single prominent nucleus
