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Question 1
Incorrect
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Regarding the varicella zoster virus, which of the following statements is CORRECT:
Your Answer: Childhood chickenpox should be treated with oral antiviral medication.
Correct Answer: Contracting chickenpox infection while pregnant is associated with a higher risk of developing varicella pneumonitis.
Explanation:Chickenpox infection in neonates, adults/adolescents and pregnant women is associated with more severe disease. Varicella zoster pneumonitis typically occurs in pregnant women or immunocompromised individuals and is associated with a high mortality. A live attenuated-virus vaccine is available and recommended for non-immune healthcare workers but is not part of the routine childhood immunisation schedule. Antiviral treatment is not typically recommended in childhood chickenpox but is indicated for shingles.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 2
Incorrect
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Clostridium difficile primarily causes which of the following infectious diseases:
Your Answer: Toxic shock syndrome
Correct Answer: Pseudomembranous colitis
Explanation:Clostridium difficile causes pseudomembranous colitis, an acute inflammatory diarrhoeal disease and an important cause of morbidity and mortality in hospitals. Gas gangrene is primarily caused by Clostridium perfringens. Tetanus is caused by Clostridium tetani. Toxic shock syndrome may be caused by Staphylococcus aureus or Streptococcus pyogenes. Necrotising fasciitis is most commonly caused by Streptococcus pyogenes but has a multitude of causes.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 3
Correct
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When a child has chickenpox, how long should he or she be off from school?
Your Answer: Until all vesicles have crusted over
Explanation:To avoid the spread of infection, infected patients should be isolated. All lesions should be crusted over before children return to nursery or school, even if the standard exclusion time is 5 days.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 4
Incorrect
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Regarding Escherichia coli, which of the following statements is INCORRECT:
Your Answer: It is a common cause of neonatal meningitis.
Correct Answer: It is a predominant member of the normal flora of the skin.
Explanation:Escherichia coli is a Gram-negative bacilli that is an important member of the intestinal flora. It is the most common cause of UTI in adults (about 70 – 95% of cases), followed by Staphylococcus saprophyticus (about 5 – 10% of cases), and an important cause of neonatal meningitis. E. coli O157 strain is implicated in the development of dysentery associated with haemolytic uraemic syndrome characterised by haemolytic anaemia, thrombocytopenia and acute renal failure.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 5
Incorrect
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Regarding Campylobacter gastroenteritis, which of the following statements is INCORRECT:
Your Answer: Bloody diarrhoea is a typical feature.
Correct Answer: Infection usually requires antibiotic treatment.
Explanation:Campylobacter jejuni is the primary human pathogen, typically causing dysentery (bloody diarrhoea illness) following ingestion of contaminated meat, especially poultry. Infection is typically self-limiting and does not require antibiotic therapy. Campylobacter gastroenteritis is associated with the immune-mediated complications of Guillain-Barre syndrome, reactive arthritis and Reiter’s syndrome.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 6
Correct
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Regarding gas gangrene, which of the following statements is CORRECT:
Your Answer: Infection is characterised by rapidly spreading tissue myonecrosis with crepitus.
Explanation:Gas gangrene usually occurs within 3 days of injury, and is characterised by pain, rapidly spreading oedema, myositis, necrosis, palpable crepitus and systemic toxicity. Diagnosis is clinical and laboratory confirmation should not delay urgent surgical intervention. Hyperbaric oxygen therapy can be considered in addition to surgery and antibiotic therapy, to stop toxin production and inhibit bacteria from replicating and spreading (as Clostridium spp. are obligate anaerobes).
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 7
Incorrect
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Which of the following pathogens is most commonly implicated in croup:
Your Answer: Respiratory syncytial virus
Correct Answer: Parainfluenza
Explanation:Parainfluenza virus is the most commonly implicated infectious agent in croup.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 8
Correct
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Which of the following statements concerning hepatitis D is TRUE:
Your Answer: It can only be transmitted with, or to somebody who is infected with, Hepatitis B.
Explanation:Hepatitis D virus (HDV) is an RNA virus that was discovered in 1977 and is structurally unrelated to the hepatitis A (HAV), hepatitis B (HBV), and hepatitis C (HCV) viruses. HDV causes a unique infection that requires the assistance of HBV viral particles to replicate and infect hepatocytes. Its clinical course is varied and ranges from acute, self-limited infection to acute, fulminant liver failure. Chronic liver infection can lead to end-stage liver disease and associated complications (including accelerated fibrosis, liver decompensation, and hepatocellular carcinoma).
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 9
Correct
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In the emergency room, a patient was diagnosed with acute bacterial tonsillitis. Which of the following postinfectious complications is most commonly linked to Streptococcus pyogenes:
Your Answer: Glomerulonephritis
Explanation:Poststreptococcal glomerulonephritis (PSGN) is caused by prior infection with specific nephritogenic strains of group A beta-haemolytic streptococcus. The clinical presentation of PSGN varies from asymptomatic, microscopic haematuria to the full-blown acute nephritic syndrome, characterized by red to brown urine, proteinuria (which can reach the nephrotic range), oedema, hypertension, and acute kidney injury.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 10
Correct
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Which of the following pathogens causes tetanus:
Your Answer: Clostridium tetani
Explanation:Tetanus is caused by Clostridium tetani, a bacterium. Tetanus can cause mild spasms to severe whole-body contractions, suffocation, and heart attack.
Gas gangrene and food poisoning are both caused by Clostridium perfringens.
Pseudomembranous colitis is caused by Clostridium difficile.
Urinary tract infections, respiratory infections, dermatitis, soft tissue infections, bacteraemia, bone and joint infections, gastrointestinal infections, and a variety of systemic infections are all caused by Pseudomonas aeruginosa.
Pharyngitis, skin infections, acute rheumatic fever, scarlet fever, poststreptococcal glomerulonephritis, toxic shock–like syndrome, and necrotizing fasciitis can all be caused by Streptococcus pyogenes infection.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 11
Correct
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Question 12
Correct
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A 6 year old boy is brought into the ED by his mom with a rash that is associated with Koplik's spots and a diagnosis of measles is made. What advice should be given about returning to school?
Your Answer: 4 days from the onset of the rash
Explanation:Prevention of spread of measles is extremely important and infected patients should be isolated. The infectious stage is from 3 days before the rash emerges and patients are advised to stay away from school/nursery/work for 4 days from onset of the rash.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 13
Correct
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Hepatitis A is transmitted by which of the following routes:
Your Answer: Faecal-oral route
Explanation:Hepatitis A transmission is by the faecal-oral route; the virus is excreted in bile and shed in the faeces of infected people.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 14
Correct
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Regarding threadworms, which of the following statements is CORRECT:
Your Answer: First line treatment of threadworms is with mebendazole.
Explanation:First line treatment of threadworms is with mebendazole, with treatment of the whole family, and a repeat treatment after 2 weeks. Threadworms live in the large bowel, but direct multiplication of worms does not occur here. Threadworms most commonly infect children, and may be symptomatic or cause pruritus ani.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 15
Incorrect
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About what percentage of patients with hepatitis A develop chronic infection:
Your Answer: 10 - 20%
Correct Answer: None
Explanation:Chronic hepatitis and carrier state does not occur in hepatitis A infection and complete immunity is attained after infection.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 16
Correct
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Clostridium tetani causes which of the following infectious diseases:
Your Answer: Tetanus
Explanation:Clostridium tetani causes tetanus.
Scarlet fever is caused by Streptococcus pyogenes.
Toxic shock syndrome is caused by Staphylococcus aureus or Streptococcus pyogenes.
Gas gangrene is primarily caused by Clostridium perfringens.
Pseudomembranous colitis is commonly caused by Clostridium difficile. -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 17
Correct
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Question 18
Correct
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Which patient group are most commonly associated with infection with Klebsiella spp:
Your Answer: Hospitalised patients
Explanation:Klebsiella spp. are facultatively anaerobic Gram-negative rods, found in the normal intestinal and respiratory flora. These organisms are usually opportunistic pathogens that cause nosocomial infections, most commonly pneumonia and UTI.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 19
Incorrect
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An elderly man with chronic heart and lung disease develops Legionnaires' Disease. By what route was the infection most likely to have been acquired:
Your Answer: Exposure to livestock or animal products
Correct Answer: Inhalation of aerosolised contaminated water
Explanation:Legionella pneumophilais a Gram negative bacterium that is found in natural water supplies and in the soil, transmitted predominantly via inhalation of aerosols generated from contaminated water (direct person-to-person spread of infected patients does not occur). It is the cause of Legionnaires’ disease. Outbreaks of Legionnaires’ disease have been linked to poorly maintained air conditioning systems, whirlpool spas and hot tubs.
The clinical features of the pneumonic form of Legionnaires’ disease include:
Mild flu-like prodrome for 1-3 days
Cough (usually non-productive and occurs in approximately 90%)
Pleuritic chest pain
Haemoptysis
Headache
Nausea, vomiting and diarrhoea
Anorexia
Legionella pneumophilainfections can be successfully treated with macrolide antibiotics, such as erythromycin, or quinolones, such as ciprofloxacin. Tetracyclines, such as doxycycline, can also be used.
The syndrome of inappropriate antidiuretic hormone secretion (SIADH) can occur with Legionnaires’ disease and will result in hyponatraemia as is seen in this case.
Legionella pneumophilainfections are resistant to amoxicillin but can be successfully treated with macrolide antibiotics, such as erythromycin, or quinolones, such as ciprofloxacin. Tetracyclines, such as doxycycline, can also be used. The majority of cases of Legionnaires’ disease are caused by Legionella pneumophila, however many other species of Legionella have been identified.
Legionella longbeachae is another less commonly encountered species that has also been implicated in outbreaks. It is predominantly found in soil and potting compost, and has caused outbreaks of Pontiac fever, the non-respiratory and less severe variant of Legionnaires’ disease. -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 20
Incorrect
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Which of the following serology results is consistent with chronic hepatitis B infection:
Your Answer: Anti-HBs positive and anti-HBc IgG negative
Correct Answer: HBsAg positive and anti-HBc IgG positive
Explanation:Disease state vs Serology
Acute hepatitis: BHBsAg, HBeAg, anti-HBc IgM
Chronic hepatitis B (low infectivity): HBsAg (>6/12), anti-HBe, anti-HBc IgG
Chronic hepatitis B (high infectivity): HBsAg (>6/12), HBeAg, anti-HBc IgG
Cleared infection: Anti-HBs, anti-HBe, anti-HBc IgG
Vaccinated: Anti-HBs -
This question is part of the following fields:
- Microbiology
- Pathogens
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