MP: Protozoa

A 30-year-old traveller develops bloody diarrhoea after returning from India. Microscopy reveals trophozoites containing ingested red blood cells. Which drug is most appropriate for treatment?

• Metronidazole

• Albendazole

• Tetracycline

• Praziquantel

A patient with chronic diarrhoea shows pear-shaped flagellated trophozoites with two nuclei and a ventral disc in stool. Which diagnostic test is most sensitive when cyst shedding is intermittent?

• Duodenal aspiration

• Direct wet mount

• Single stool examination

• Formalin-ether concentration

A pig farmer presents with mucoid, bloody diarrhoea. Microscopy reveals large ciliated trophozoites with a peristome and kidney-shaped macronucleus. What is the likely pathology?

• Ulceration of intestinal mucosa

• Hepatic abscess

• Bile duct obstruction

• Villous atrophy

A hospital outbreak of watery diarrhoea occurs among immunocompromised patients. Modified acid-fast staining reveals small red spherical oocysts. Which control measure is most effective?

• Boiling drinking water

• Chlorination of water

• Use of insect repellents

• Anthelmintic mass treatment

A woman presents with vaginal itching and frothy discharge. Wet mount shows motile flagellated protozoa lacking a cyst stage. What feature differentiates this organism from intestinal protozoa?

• Absence of cyst stage

• Cyst formation in intestine

• Infection via contaminated food

• Transmission by arthropods

A stool sample from a healthy individual shows cysts with eight nuclei but no evidence of disease. Which organism is most likely?

• Entamoeba coli

• Entamoeba histolytica

• Giardia duodenalis

• Balantidium coli

A child presents with profuse watery diarrhoea. Acid-fast stain shows oocysts larger than Cryptosporidium but smaller than Isospora. What is the causative agent?

• Cyclospora cayetanensis

• Cryptosporidium parvum

• Cystoisospora belli

• Giardia duodenalis

A 25-year-old woman develops diarrhoea after antibiotic therapy. Cysts with a large glycogen vacuole and eccentric karyosome are seen. Which organism is most consistent?

• Endolimax nana

• Iodamoeba butschlii

• Entamoeba coli

• Giardia duodenalis

A 5-year-old child has foul-smelling stools and weight loss. Microscopy reveals cysts with four nuclei and axonemes. Which structure is responsible for intestinal attachment?

• Ventral sucking disc

• Flagella

• Axostyle

• Cytostome

A laboratory technician finds oval oocysts measuring 20–30 µm containing two sporocysts in a stool sample from an AIDS patient. Which protozoan is identified?

• Cystoisospora belli

• Cyclospora cayetanensis

• Cryptosporidium parvum

• Entamoeba histolytica