Question 1

The bacterium that plays a major role in the development of gastric ulcers is

Accepted Answer

Helicobacter pylori is a bacterium that colonizes the mucous layer of the stomach and is strongly linked with the development of gastric ulcers. Salmonella enteritidis and Salmonella typhi are associated with foodborne illnesses and Vibrio parahaemolyticus is associated with seafood poisoning, but they are not typically associated with gastric ulcers. Therefore, choice B is the best answer.

Question 2

Which of the following bacteria cause gastrointestinal symptoms that are due to an exotoxin?

Accepted Answer

All of the choices listed, Staphylococcus aureus, Clostridium perfringens, Vibrio cholerae, and E. coli, are bacteria that can cause gastrointestinal symptoms through the production of exotoxins.

Question 3

Which of the following is TRUE concerning hydatid disease?

Accepted Answer

Hydatid disease, also known as echinococcosis, is caused by the tapeworm Echinococcus granulosus. Dogs (and other canids) are the definitive hosts, meaning the parasite reaches maturity and reproduces sexually in them. Humans become infected by ingesting the eggs of E. granulosus, which can occur through direct contact with infected dogs or by consuming contaminated food or water. Once ingested, the eggs hatch in the intestine, and the larvae then penetrate the intestinal wall and enter the bloodstream, through which they can reach and form cysts in various organs. These cysts, known as hydatid cysts, can indeed contain thousands of protoscolices, which are capable of developing into new tapeworms if ingested by a definitive host, completing the lifecycle.

Question 4

Which of the following food poisoning organisms produces almost immediate gastrointestinal symptoms (within hours)?

Accepted Answer

Staphylococcus aureus produces almost immediate gastrointestinal symptoms, typically within hours of ingestion. The other organisms listed may have an incubation period of several days before symptoms develop.

Question 5

Which of the following does NOT cause hepatitis in humans?

Accepted Answer

Rubeola virus causes measles, which is a viral illness that presents with a characteristic rash and other symptoms, but it does not cause hepatitis.

Question 6

Hepatitis A

Accepted Answer

Hepatitis A does not generally cause chronic infection, distinguishing it from some other types of hepatitis, such as hepatitis B and C, which can become chronic in some individuals.

Question 7

Cryptosporidium parvum gastroenteritis

Accepted Answer

Cryptosporidium parvum gastroenteritis can occur in outbreaks due to contamination of swimming pools. It is not notifiable in Australia because of its low incidence rates. It is not uncommon, despite having a high infective dose, and typically does not result in cyst formation in the liver and spleen.

Question 8

Hookworm infestation

Accepted Answer

Hookworm infestation can cause iron deficiency and anaemia due to the blood-sucking nature of the hookworms.

Answer:B 
 This statement is incorrect. Hookworm infestation can cause symptoms such as abdominal pain, diarrhoea, and nausea, but it is not always characterised by bloody diarrhoea.

Answer:C 
 This statement is incorrect. Hookworm larvae can migrate to other tissues, such as the lungs or skin, before returning to the intestine.

Answer:D 
 Hookworm infestation occurs when the larvae penetrate the skin, usually through the feet, and enter the bloodstream. It is not typically transmitted through contaminated drinking water.

Answer:A 
 The correct option is A since hookworm infestation can cause iron deficiency and anaemia. Option B is incorrect since hookworm infestation is not always characterised by bloody diarrhea. Option C is incorrect because hookworm larvae can migrate to other tissues before returning to the intestine. Option D is incorrect since hookworm infestation occurs when larvae penetrate the skin, not through contaminated drinking water.

Question 9

A nurse suffers a needlestick injury with a needle used on a patient with confirmed hepatitis B.If she has not previously had any hepatitis B immunisation the most important immediate treatment she should receive is

Accepted Answer

The immediate treatment for a nurse suffering a needlestick injury with a needle used on a patient with confirmed hepatitis B should be administration of hepatitis B immunoglobulin to provide passive immunity against the infection. The nurse should also receive the hepatitis B vaccine as soon as possible, as hepatitis B is a vaccine-preventable disease. Alpha interferon and aciclovir are not appropriate treatments for hepatitis B. HBsAg is a test used to diagnose hepatitis B, not a treatment.

Question 10

Probiotics are

Accepted Answer

Probiotics are formulations of microorganisms that may provide a health benefit. They are often used as dietary supplements to promote gut health and improve immune function.

Question 11

Typhoid fever

Accepted Answer

Typhoid fever is caused by the bacterium Salmonella enterica serotype Typhi. The organism can multiply within phagocytes and cause systemic infection throughout the body, leading to symptoms such as fever, abdominal pain, and diarrhea. It is most commonly spread through contaminated food or water.

Question 12

What is the most common risk factor for hepatitis C virus infection in developed countries?

Accepted Answer

In developed countries, the most common risk factor for hepatitis C virus infection is intravenous drug abuse, particularly when needles are shared among users. This is because the hepatitis C virus can be easily transmitted through exposure to infected blood.  Blood transfusions were previously a major risk factor, but improved screening methods have significantly reduced the risk of contracting hepatitis C virus from blood transfusions. Unprotected sex and perinatal transmission are also possible modes of transmission, but they are less common. Mosquito bites are not a risk factor for hepatitis C virus transmission.

Question 13

An effective treatment for chronic Clostridium difficile diarrhoea is

Accepted Answer

Faecal microbiota transplant has been shown to be highly effective in treating recurrent Clostridium difficile infections by restoring the patient's gut flora. Colonic cleansing may provide temporary relief but does not address the underlying cause of the infection. A high-fibre diet may help prevent C. difficile infections, but it is not an effective treatment. Antiviral and corticosteroid therapies are not effective against bacterial infections such as C. difficile.

Question 14

Infection with the pinworm Enterobius vermicularis

Accepted Answer

Infection with the pinworm E. vermicularis is characterised by anal itching.

Note: A is incorrect as pinworm infection is actually quite common in Australia. C is incorrect as the eggs of E. vermicularis are ingested and hatch in the small intestine, not penetrate the skin. D is incorrect as E. vermicularis does not cause lung disease.

Question 15

Listeria monocytogenes

Accepted Answer

Listeria monocytogenes can cause serious infections in pregnant women, leading to foetal infections and even stillbirth. It is not spread directly from person to person and is not endemic in the northern parts of Australia.

Question 16

The giant roundworm that can lay around 200 000 eggs a day in the intestine of an infected person is

Accepted Answer

Ascaris lumbricoides is known to lay around 200,000 eggs per day in the intestine of an infected person.

Question 17

Which of the following statements is FALSE?

Accepted Answer

Not all patients who have typhoid become chronic carriers. Only about 2-5% of cases result in chronic carriers.

Question 18

Which of the hepatitis viruses,for which there is no vaccine,may cause a chronic infection?

Accepted Answer

Hepatitis C is the hepatitis virus for which there is no vaccine and may cause a chronic infection. Chronic hepatitis C infection can lead to liver damage, cirrhosis, and liver cancer. Vaccines are available for hepatitis A and hepatitis B, while hepatitis D is only a concern for individuals with hepatitis B and there is a vaccine for hepatitis E in some countries.

Question 19

Hepatitis B can be transmitted by

Accepted Answer

Hepatitis B can be transmitted through male homosexual contact, exposure to infected patient blood, at birth from an infected mother to baby, and intravenous drug use. All of the above are risk factors for contracting the virus.

Question 20

Which of the following could be transmitted by needlestick injury?

Accepted Answer

All three types of hepatitis (B, C, and D) can be transmitted through needlestick injuries. It's crucial for healthcare workers and others at risk of needlestick injuries to follow proper safety protocols to reduce their risk of infection.

Quiz 18: Gastrointestinal Tract Infections