MI4.1-9 | Gastrointestinal & Hepatobiliary Infections — Practice Quiz

A 5-year-old child in a rural Indian village develops profuse watery diarrhoea with 'rice-water' stools, no fever, and signs of severe dehydration within hours. The stool microscopy shows no pus cells. Which single mechanism best explains the diarrhoea?

On stool microscopy, a technician reports 'trophozoites with ingested RBCs and a single nucleus with central karyosome'. Which organism and disease does this describe?

Fifteen guests at a wedding develop explosive vomiting within 2 hours of eating cream pastries. There is no fever. Leftover food re-heated by the caterer tested 'bacteria-negative'. What is the most likely explanation?

A 45-year-old man has epigastric pain, positive CLO test on biopsy, and elevated serum IgG anti-H. pylori antibody. He is prescribed triple therapy. Which property of H. pylori allows it to survive in the gastric mucus layer?

During a hepatitis B serology interpretation exercise, a student sees: HBsAg negative, anti-HBs negative, anti-HBc IgM positive. What does this pattern indicate?

Rotavirus is the most common cause of severe dehydrating diarrhoea in Indian children under 5 years. Which structural feature of the virion is directly responsible for its characteristic appearance on electron microscopy?

A pregnant woman in her third trimester develops fulminant hepatic failure during a hepatitis outbreak in a flood-affected area. Which hepatitis virus is most likely responsible, and what is the approximate case fatality rate in this group?

Shigella dysenteriae type 1 produces Shiga toxin. Which is the precise molecular target of this toxin inside the host cell?

A laboratory receives a stool sample with the request to rule out cholera. Which combination of culture media and presumptive colony appearance would be correct?

Which hepatitis B viral marker is NEVER detectable in the serum of an infected patient but is the basis of the hepatitis B vaccine?