MCQs on Intestinal parasites/protozoa : Medical microbiology

                               MCQs on Intestinal parasites/protozoa

           

                                        Figure: Giardia duodenalis/Giardia intestinalis cytology

Amoebae (intestinal):

1. What is the primary causative agent of intestinal amoebiasis?
a) Entamoeba coli     
b) Entamoeba histolytica   
c) Giardia duodenalis   
d) Trichomonas vaginalis

2. How is amebiasis most commonly transmitted to humans?
a) Ingestion of food or water contaminated   
b) Inhalation of aerosolized cysts
c) Mosquito bites   
d) Person-to-person contact

3. What are the typical symptoms of amebiasis?
a) Abdominal cramps and vomitting

b) Cough and chest pain 

c) Diarrhea, abdominal pain, and bloody stools    

d) Joint pain and swelling

4. In amebiasis, when Entamoeba histolytica invades organs besides the intestines, which organ is most commonly affected?
a) Brain
b) Kidneys
c) Lungs
d) Liver     

5. How is amebiasis diagnosed?
a) Blood test
b) Stool examination for cysts and trophozoites      
c) Skin biopsy
d) Urine analysis

6. What is the primary treatment for amebiasis caused by Entamoeba histolytica?
a) Antibiotics such as metronidazole     
b) Antimalarial drugs
c) Antifungal medications
d) Corticosteroids

7. Which preventive measures are recommended to reduce the risk of amebiasis?
a) Avoiding handwashing
b) Consuming raw and undercooked meat
c) Drinking untreated surface water

d) Practicing good hygiene and sanitation

8. Which microscope objective lens is typically used for initial scanning and locating parasites in a stool sample?

a) 4x

b) 10x

c) 40x

d) 100x    

Flagellates (intestinal):

1. What is the typical mode of transmission for Giardia duodenalis?

a) Inhalation of cysts

b) Skin contact with contaminated water

c) Ingestion of cysts in contaminated water or food    

d) Sexual transmission

2. Which of the following flagellate that lacks a cyst stage is often associated with gastrointestinal symptoms such as diarrhea, abdominal pain, and fatigue?

a) Dientamoeba fragilis     

b) Enteromonas hominis

c) Giardia duodenalis

d) Trichomonas intestinalis

3. How is Trichomonas intestinalis usually diagnosed in individuals with suspected trichomoniasis?

a) Blood test

b) Chest X-ray 

c) Identifying trophozoites in stool samples     

d) Urine analysis

4. Which of the following flagellates is considered nonpathogenic and typically not requiring treatment?

a) Chilomastix mesnili     

b) Dientamoeba fragilis

c) Giardia duodenalis

d) Trichomonas intestinalis

5. Which concentration method is commonly used to increase the chances of detecting protozoa in stool samples?

a) Blood agar culture

b) Iodine staining

c) Magnetic resonance imaging

d) Zinc sulfate centrifugation

Ciliates (intestinal):

1. Which ciliate is responsible for causing balantidiasis, a gastrointestinal infection primarily affecting the large intestine?

a) Balantidium coli    

b) Entamoeba histolytica

c) Giardia duodenalis

d) Isospora belli

2. Which of the following symptoms is commonly associated with isosporiasis caused by Isospora belli?

a) Joint pain and fatigue

b) Persistent cough and chest pain

c) Skin rash and fever  

d) Watery diarrhea and abdominal cramps   

3. How is Isospora belli infection usually diagnosed in individuals with suspected isosporiasis?

a) Blood test

b) Chest X-ray

c) Identifying oocysts in stool samples   

d) Urine analysis

4. Which of the following medications is commonly used for the treatment of balantidiasis caused by Balantidium coli?

a) Albendazole

b) Metronidazole

c) Metronidazole

d) Tetracycline    

Coccidia and Microsporidia:

1. What is the most common species associated with intestinal microsporidiosis in humans?

a) Balantidium coli

b) Entamoeba histolytica

c) Enterocytozoon bieneusi      

d) Giardia lamblia

2. Which of the following symptoms is commonly associated with intestinal microsporidiosis?

a) Bloody diarrhea

b) Chronic diarrhea, weight loss, and abdominal cramps      

c) Persistent cough and chest pain

d) Skin rash and joint pain

3. What is the primary method of diagnosing intestinal microsporidiosis in individuals with suspected infections?

a) Blood test

b) Chest X-ray

c) Identifying Microsporidia spores in stool samples     

d) Urine analysis

4. Which of the following medication is commonly used for the treatment of intestinal microsporidiosis?

a) Albendazole    

b) Ivermectin

c) Metronidazole

d) Tetracycline

5. Which of the following parasite causes infection particularly in individuals with weakened immune system and leads to diarrhea and dehydration?

a) Cryptosporidium parvum

b) Cyclospora cayetanensis

c) Cystoisospora belli

d) Enterocytozoon bieneusi

6. Which staining method is often used to detect Cryptosporidium oocysts?

a) Acid fast staining

b) Gram staining

c) Giemsa stain

d) Wright stain

Answers:

Amoebae (intestinal):

1. b) Entamoeba histolytica. It causes amoebiasis, which can range from mild diarrhea to severe, potentially life-threatening colitis or liver abscesses. It is particularly common in regions with poor sanitation and hygiene.

2. a) Ingestion of food or water contaminated with E. histolytica cysts
3. c) Diarrhea, abdominal pain, and bloody stools. The symptoms can range from mild diarrhea to severe, potentially life-threatening colitis or liver abscesses.

4. d) Liver. The parasite causes amoebiasis, which can range from mild diarrhea to severe, potentially life-threatening colitis or liver abscesses. 

5. b) Stool examination for cysts and trophozoites. Trophozoites are the active, motile stage of many intestinal protozoa. Cysts and trophozoites are often the primary diagnostic form observed in stool samples.

6. a) Antibiotics such as metronidazole
7. c) Practicing good hygiene and sanitation

8. a) 4x. The 4x objective lens is typically used for initial scanning and locating parasites in a stool sample. It provides a wide field of view, allowing the observer to search the specimen efficiently before using higher magnifications for detailed examination.

Flagellates (intestinal):

1. c) Ingestion of cysts in contaminated water or food. Giardia is one of the most prevalent intestinal parasites worldwide. It causes a condition known as giardiasis, which results in symptoms like diarrhea, abdominal pain, bloating, and weight loss.  

2. a) Dientamoeba fragilis. It is a flagellated protozoan, but it lacks a cyst stage, which is in contrast to many other intestinal parasites. It exists primarily as a trophozoite form with a nucleus and a single central karyosome. Not all individuals infected with D. fragilis exhibit symptoms, the typical symptoms observed in infected individuals include diarrhea, abdominal pain, bloating, and weight loss.   

3. c) Identifying trophozoites in stool samples 

4. a) Chilomastix mesnili. It is a flagellated protozoan parasite that can be found in the human intestines and is considered to be non-pathogenic or commensal in humans.

5. d) Zinc sulfate centrifugation. It is a common concentration method used in the laboratory to increase the chances of detecting protozoa in stool samples. It helps to concentrate and separate parasites from other stool components.

Ciliates (intestinal):

1. a) Balantidium coli  

2. d) Watery diarrhea and abdominal cramps. The parasite causes an infection called isosporiasis, which can lead to diarrhea, cramps, and weight loss. It often affects individuals with compromised immune systems.  

3. c) Identifying oocysts in stool samples

4. d) Tetracycline

Coccidia and Microsporidia:

1. c) Enterocytozoon bieneusi 

2. b) Chronic diarrhea, weight loss, and abdominal cramps 

3. c) Identifying Microsporidia spores in stool samples

4. a) Albendazole

5. a) Cryptosporidium parvum. It is responsible for cryptosporidiosis, which leads to diarrhea, stomach cramps, and dehydration. It is a significant concern for individuals with weakened immune systems.

6. a) Acid fast staining. Cryptosporidium oocysts are often detected using modified acid-fast staining, which makes them stand out as bright red or pink against a blue or green background under the microscope.