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Question 1
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 2
Incorrect
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The tetanus vaccination contains inactivated tetanus toxoid, which induces the body to produce protective antibodies. How do these antibodies protect the body from tetanus?
Your Answer: Prevent binding of C. tetani endotoxin to monocyte receptors
Correct Answer: Neutralise the protein exotoxin of C. tetani
Explanation:C. Tetanospasmin, an exotoxin produced by tetani, is responsible for the neurotoxic consequences of tetanus. The tetanus vaccination contains inactivated tetanus toxoid, which induces the body to produce protective antibodies that neutralize the tetanus toxin. It induces active immunization against Clostridium tetani exotoxin via toxoid-induced Ab generation.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 3
Incorrect
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Which of the following is NOT a typical complication associated with mumps:
Your Answer: Pancreatitis
Correct Answer: Subacute sclerosing panencephalitis
Explanation:Complications of mumps include meningitis, post meningitis deafness, encephalitis, pancreatitis, orchitis and oophoritis. Subacute sclerosing panencephalitis is a complication typically associated with measles infection.
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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 hepatitis C, which of the following statements is INCORRECT:
Your Answer: Hepatitis C becomes chronic in about 80% of infected patients.
Correct Answer: Anti-HCV IgG antibodies are diagnostic of acute infection.
Explanation:Anti-HCV IgG antibodies indicate exposure to hepatitis C but this could be acute, chronic or resolved infection. If the antibody test is positive, HCV RNA should be tested for, which if positive indicates that a person has current infection with active hepatitis C.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 5
Correct
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You suspected a fungal nail infection in a 50-year-old man who presented with an itchy, scaly rash between his toes and a thicker, discoloured nail on his big toe that has been there for almost one month already. Which of the following tests is most likely to confirm your suspected diagnosis?
Your Answer: Nail clippings for microscopy and culture
Explanation:Nail clippings for microscopy and culture are a diagnostic test for fungal infection. Because some fungi are restricted to the lower parts of the nail, clippings should be taken from the discoloured or brittle parts and cut back as far as possible from the free edge.
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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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Which of the following virulence factors of E. coli is important for attachment to host epithelial cells in the pathogenesis of urinary tract infections:
Your Answer: Pili
Explanation:Escherichia coli is the most common cause of urinary tract infection. Uropathic strains are characterised by pili with adhesion proteins that bind to specific receptors on the urinary tract epithelium. The motility of E. coli aids its ability to ascend the urethra into the bladder or ascend the ureter into the kidney.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 7
Correct
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You received a patient with a 2-day history of diarrhoea and vomiting. Later, after examination, the patient was found to have progressive symmetric descending flaccid paralysis, initial development of blurred vision, dysphagia, and weakness of the upper limbs. The patient is apyrexial and his observations are all normal. Which of the following pathogens is responsible for the said symptoms?
Your Answer: Clostridium botulinum
Explanation:A botulism infection results in neuroparalysis caused by the neurotoxin generated by Clostridium botulinum. Food-borne botulism symptoms often appear 12-36 hours after ingestion of the toxin-containing food and may include nausea, vomiting, stomach discomfort, and diarrhoea at first. The most common neurological pattern is an acute onset of bilateral cranial neuropathies with symmetric declining weakening. Other distinguishing characteristics include the absence of fever, the absence of cognitive abnormalities, the presence of a normal heart rate and blood pressure, and the absence of sensory defects.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 8
Incorrect
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Regarding Helicobacter pylori, which of the following statements is INCORRECT:
Your Answer: It is motile.
Correct Answer: It is found as part of normal colonic flora.
Explanation:Helicobacter pyloriis a Gram-negative, helix shaped (curved rod), microaerophilic bacterium. It typically has 4-6 lophotrichous flagellae and is therefore highly motile. It has an outer membrane consisting of phospholipids and lipopolysaccharide.Helicobacter pyloriIs found in the upper gastrointestinal tract of approximately 50% of the population.Colonization withHelicobacter pyloriconfers a 10-20% lifetime risk of developing peptic ulcers and a 1-2% lifetime risk of developing gastric cancer.There is a strong association between mucosa-associated lymphoid tissue (MALT) lymphoma andHelicobacter pyloricolonization.The most reliable method for testing for colonization withHelicobacter pyloriis by biopsy during endoscopy and histological examination.Typically eradication requires a 14-day course of triple therapy with amoxicillin, clarithromycin and a proton pump inhibitor. Metronidazole is also often used as an alternative antibiotic in a triple therapy regime.Serum antibody levels fall slowly and therefore cannot be used to accurately assess eradication. Either of the 13C-urea breath test or the stool antigen test are viable options for assessing successful eradication.
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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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Bordetella pertussis causes which of the following infectious diseases:
Your Answer: Whooping cough
Explanation:Bordetella pertussis causes whooping cough. Acute bronchiolitis is typically caused by respiratory syncytial virus. Parainfluenza virus is the most common cause of croup. Acute epiglottitis is usually caused by an infection with Haemophilus influenzae type b (Hib) bacteria. The common cold may be caused by a number of viruses including rhinovirus and coronavirus.
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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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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: 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 daysCough (usually non-productive and occurs in approximately 90%)Pleuritic chest painHaemoptysisHeadacheNausea, vomiting and diarrhoeaAnorexiaLegionella 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.
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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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A blood test of a 7-year-old child with a 6-day history of bloody diarrhoea reveals a low platelet count, anaemia, and impaired kidney function. What bacteria is suspected of causing such a condition?
Your Answer: Escherichia coli
Explanation:Escherichia coli produces shiga toxin that causes diarrhoea, hemorrhagic colitis, and haemolytic uremic syndrome. Haemolytic uremic syndrome is characterized by anaemia, thrombocytopenia, and acute renal failure. Transmission of E. coli is possible after consuming contaminated, undercooked drinks and foods. E. coli enters the body via the faecal-oral pathway.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 12
Incorrect
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Which of the following antibiotics is the first line of treatment for a patient who has been diagnosed with chlamydia infection?
Your Answer: Erythromycin
Correct Answer: Azithromycin
Explanation:The Centres for Disease Control and Prevention (CDC) recommends azithromycin, a single 1 g dose, and doxycycline, 100 mg bd for 7 days, as first-line medications for chlamydial infection treatment. Second-line medications (such as erythromycin, penicillins, and sulfamethoxazole) are less effective and have more side effects
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 13
Incorrect
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A 18 year old university student develops facial swelling and dark frothy urine. Urine dipstick demonstrates haematuria and proteinuria. Approximately 3 weeks ago, he was treated with oral antibiotics for a sore throat. His condition is most likely to be secondary to infection with:
Your Answer: Escherichia coli
Correct Answer: Streptococcus pyogenes
Explanation:Post-streptococcal glomerulonephritis is a postinfectious immune-mediated reaction secondary to infection with Streptococcus pyogenes. It typically occurs 2 weeks or more after acute/initial infection, and presents with haematuria, reduced urine output, peripheral oedema, proteinuria, and hypertension. Permanent kidney damage is rare.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 14
Incorrect
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Regarding threadworms, which of the following statements is CORRECT:
Your Answer: Symptoms are usually of abdominal discomfort and a change in bowel habit.
Correct 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
Correct
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Regarding Clostridium species, which of the following statements is INCORRECT:
Your Answer: They are facultative anaerobes.
Explanation:Clostridium spp. are obligatory anaerobic spore-forming Gram-positive bacilli. Toxin production is the main pathogenicity mechanism.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 16
Incorrect
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The percentage of patients with hepatitis B that develop chronic infection is about:
Your Answer: 20%
Correct Answer: 10%
Explanation:With hepatitis B, about 90% of people will develop lifelong immunity after clearing the infection. Chronic hepatitis develops in about 10% of patients and this may be complicated by cirrhosis or hepatocellular carcinoma. There is a very high risk of chronic infection and hepatocellular carcinoma when there is congenital infection. The risk of this in healthy adults is only about 5%.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 17
Incorrect
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Regarding the varicella zoster virus, which of the following statements is CORRECT:
Your Answer: The varicella zoster vaccine is part of routine childhood immunisation.
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 18
Correct
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Infection with Campylobacter jejuni is one of the most common risk factors for which of the following conditions?
Your Answer: Guillain-Barre syndrome
Explanation:One of the most common risk factors for GBS is infection with Campylobacter jejuni, which causes diarrhoea. Guillain-Barré syndrome (GBS) is a rare autoimmune disorder in which the body’s immune system attacks the nerves, resulting in muscle weakness and paralysis. Infection with Streptococcus pyogenes can cause acute glomerulonephritis and rheumatic fever. Haemolytic uraemic syndrome is commonly linked to E. coli infection. Following measles infection, subacute sclerosing panencephalitis develops.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 19
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 20
Incorrect
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Regarding hepatitis A, which of the following statements is CORRECT:
Your Answer: Disease is most severe in children and infants.
Correct Answer: Anti-HAV IgM antibodies are diagnostic.
Explanation:Anti-HAV IgM antibodies are diagnostic. Disease in children is more commonly asymptomatic, risk of symptomatic disease increases with age. Transmission is by the faecal-oral route. Faecal shedding has been demonstrated for 2 – 3 weeks before and about a week after, the onset of jaundice. Infection confers lifelong immunity.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 21
Incorrect
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Regarding Clostridium tetani, which of the following statements is CORRECT:
Your Answer: Tetanolysin impairs release of GABA at the presynaptic membrane.
Correct Answer: Metronidazole is usually the antibiotic of choice for tetanus infection.
Explanation:Clostridium tetani infection is predominantly derived from animal faeces and soil. Clostridium tetani has exotoxin-mediated effects, predominantly by tetanospasmin which inhibits the release of GABA at the presynaptic membrane throughout the central and peripheral nervous system. Metronidazole has overtaken penicillin as the antibiotic of choice for treatment of tetanus (together with surgical debridement, tetanus toxoid immunisation, and human tetanus immunoglobulin).
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 22
Correct
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Which of the following problems is associated with Helicobacter pylori infection?
Your Answer: Gastric malignancy
Explanation:Helicobacter pylori is a ubiquitous organism that is present in about 50% of the global population. Chronic infection with H pylori causes atrophic and even metaplastic changes in the stomach, and it has a known association with peptic ulcer disease. The most common route of H pylori infection is either oral-to-oral or faecal-to-oral contact.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 23
Incorrect
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Regarding Legionella species which of the following statements is CORRECT:
Your Answer: They are transmitted via the respiratory droplet route.
Correct Answer: They are Gram-negative organisms.
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 daysCough (usually non-productive and occurs in approximately 90%)Pleuritic chest painHaemoptysisHeadacheNausea, vomiting and diarrhoeaAnorexiaLegionella 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.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 24
Correct
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A 57-year old man presented himself to the emergency room with persistent cough. During history taking, a record of his previous sputum sample was seen and the report stated that it tested positive for AFB (acid-fast bacilli). What is the most likely pathogen?
Your Answer: Mycobacterium tuberculosis
Explanation:M. tuberculosis is the causative agent of pulmonary tuberculosis (TB). The most commonly used diagnostic test for the diagnosis of pulmonary TB is the direct sputum smear microscopy (DSSM) wherein the presence of acid-fast bacilli (AFB) is tested. The most common method is the hot method or also known as Ziehl-Neelsen method. This is a staining method special for Mycobacteria species because they are known to be acid-fast which means that they are not easily decolorized by acid alcohol. Once the DSSM tests positive for acid-fast bacilli, this indicates possible infection with tuberculosis. The gold standard for diagnosis is still culture but Mycobacteria species are slow-growers that is why DSSM is considered the best diagnostic method. A positive AFB smear and correlation with symptoms is usually used by physicians to create a final diagnosis of pulmonary tuberculosis.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 25
Correct
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Campylobacter jejuni is primarily spread via which of the following routes:
Your Answer: Faecal-oral route
Explanation:Campylobacter spp. are a common cause of acute infective gastroenteritis, particularly in children, with Campylobacter jejuni responsible for 90% of Campylobacter gastroenteritis. Infection typically follows ingestion of contaminated meat (most frequently undercooked poultry), unpasteurised milk or contaminated water, following which the microorganism invades and colonises the mucosa of the small intestine.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 26
Correct
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Regarding Escherichia coli, which of the following statements is INCORRECT:
Your 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 27
Correct
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Which of the following statements regarding hookworm is FALSE:
Your Answer: Transmission of hookworm is via ingestion of contaminated food and water.
Explanation:The hookworm life cycle begins with the passage of eggs from an adult host into the stool. Hookworm eggs hatch in the soil to release larvae that mature into infective larvae. Infection is usually transmitted by larval penetration into human skin (duodenal infection may also be transmitted by the oral route). From the skin, larvae migrate into the blood vessels and are carried to the lungs, where they penetrate the pulmonary alveoli, ascend the bronchial tree to the pharynx, and are swallowed.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 28
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 29
Correct
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Bordetella pertussis is spread via which of the following routes:
Your Answer: Respiratory droplet route
Explanation:Bordetella pertussis is a Gram negative coccobacillus that causes whooping cough. B. pertussis is spread via the respiratory droplet route and expresses fimbriae that aid their adhesion to the ciliated epithelium of the upper respiratory tract, and produce a number of exotoxins, causing the characteristic thickened bronchial secretions, paralysis of cilia and lymphocytosis.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 30
Correct
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Regarding Clostridium tetani, which of the following statements is CORRECT:
Your Answer: Infection is predominantly derived from animal faeces and soil.
Explanation:Clostridium tetaniis a Gram positive, rod shaped, obligate anaerobic bacterium.The incubation period is quoted as anywhere between 4-21 days and can occur after several months but symptoms usually occur within the first 7 days after exposure.Approximately 80% of patients develop generalised tetanus. The commonest presenting feature of generalised tetanus is trismus (lockjaw), occurring in approximately 75% of affected individuals. Other clinical features include:Facial spasms (risus sardonicus)Opisthotonus (characteristic body shape during spasms)Neck stiffnessDysphagiaCalf and pectoral muscle rigidityFeverHypertensionTachycardiaSpasms can occur frequently and last for several minutes, they can continue to occur for up to 4 weeks. Current mortality rates are between 10 and 15%.Tetanic spasms are caused by the exotoxin tetanospasmin. The effects of tetanolysin are not fully understood but it is not believed to have clinical significance.Localised tetanus is a rare form of the disease, occurring in around 1% of affected individuals. Patients have persistent contraction of muscles in the same anatomic area as the injury. It may precede generalised tetanus.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 31
Correct
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Which of the following could denote a diagnosis of acquired immunodeficiency syndrome (AIDS) in a patient infected with HIV:
Your Answer: CD4 count < 200 cells/uL
Explanation:A diagnosis of AIDS can be made in a patient infected with HIV if the patient has a CD4 count < 200 cells/uL, or an AIDS-defining illness. Antiretroviral treatment should be considered in patients with CD4 counts < 350 cells/uL. Oral candidiasis is not an AIDS defining illness – candidiasis of the bronchi, trachea or lungs or of the oesophagus is an AIDS defining illness. A positive p24 antigen test seen in early HIV infection and does not indicate the development of AIDS.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 32
Correct
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Regarding dermatophytes, which of the following statement is CORRECT:
Your Answer: Diagnosis is made from microscopy and culture of skin scrapings, hair samples or nail clippings.
Explanation:Diagnosis is made from microscopy and culture of skin scrapings, hair samples or nail clippings depending on the site of infection. The lesions of ringworm typically have a dark outer ring with a pale centre. Tinea capitis is ringworm affecting the head and scalp. Spread is via direct skin contact. Treatment is usually topical, oral antifungals are reserved for refractory infection.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 33
Incorrect
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A 5 day old, full term neonate is with a unilateral purulent eye discharge noticed earlier that day is brought in. On gram stain of the exudate, no bacteria are seen. What is the most likely causative pathogen?
Your Answer: Neisseria gonorrhoea
Correct Answer: Chlamydia trachomatis
Explanation:Conjunctivitis occurring in the first 28 days of life (Ophthalmia neonatorum) is most commonly caused by Chlamydia trachomatis in the UK.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 34
Correct
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A patient presents to ED complaining of a purulent discharge, urethral discomfort and dysuria. You suspect gonorrhoea. Which of the following cell components produced by Neisseria gonorrhoeae is responsible for attachment to host cells:
Your Answer: Pili
Explanation:Infection of the genital mucosa by Neisseria gonorrhoeae involves attachment to and invasion of epithelial cells. Initial adherence of gonococci to columnar epithelial cells is mediated by type IV pili assembled from pilin subunit PilE proteins and pilus tip-associated PilC proteins, it then invades the epithelial layer, triggering a local acute inflammatory response.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 35
Correct
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Regarding Clostridium difficile, which of the following statements is CORRECT:
Your Answer: It is normally found in gut flora.
Explanation:C. difficile is normally found in the gut flora but its growth is normally suppressed by more dominant anaerobes. It has exotoxin-mediated effects causing profuse diarrhoea. Oral clindamycin (a broad spectrum antibiotic) is commonly implicated in precipitating C. difficile colitis; first line treatment is with oral metronidazole. Tetanolysin is a toxin produced by Clostridium tetani bacteria.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 36
Correct
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About what percentage of patients with hepatitis A develop chronic infection:
Your 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 37
Incorrect
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Which of the following is diagnostic for acute hepatitis B infection:
Your Answer: HBsAg
Correct Answer: anti-HBc IgM
Explanation:Anti-HBc IgM antibodies are diagnostic for acute hepatitis B infection. Anti-HBc IgG antibodies indicate previous exposure, either chronic state or cleared infection. HBsAg is also positive in acute infection but is not diagnostic as this remains positive in chronic infection.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 38
Correct
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How is measles primarily transmitted:
Your Answer: Respiratory droplet route
Explanation:Measles belongs to the paramyxoviridae group of viruses. The incubation period is 7-18 days (average 10) and it is spread by airborne or droplet transmission. The classical presentation is of a high fever with coryzal symptoms and photophobia with conjunctivitis often being present. The rash that is associated is a widespread erythematous maculopapular rash. Koplik spots are pathognomonic for measles, and are the presence of white lesions on the buccal mucosa.Differential diagnoses would include:RubellaRoseola infantum (exanthem subitom)Scarlet feverKawasaki diseaseErythema infectiosum (5thdisease)EnterovirusInfectious mononucleosisDiagnosis can be confirmed by the following means:Salivary swab for measles specific IgMSerum sample for measles specific IgMSalivary swab for RNA detectionPossible complications include:Otitis mediaFebrile convulsionsPneumoniaBronchiectasisDiarrhoeaMeningitisEncephalitisImmunosuppressionSubacute sclerosing panencephalitisDeath
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 39
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 40
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 41
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 42
Correct
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Cryptococcus neoformans is primarily transmitted by which of the following routes:
Your Answer: Inhalation of spores
Explanation:Cryptococcus neoformans is found in bird droppings and transmission is by inhalation of spores, thus the lung is the primary site of infection.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 43
Correct
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Diagnosis of HIV is predominantly made through which of the following:
Your Answer: Antibody detection
Explanation:Diagnosis of HIV is predominantly made through detection of HIV antibody and p24 antigen. Viral load (viral PCR) and CD4 count are used to monitor progression of disease.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 44
Correct
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Question 45
Incorrect
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Regarding tapeworm, which of the following statements is CORRECT:
Your Answer: Humans may be infected by pork tapeworm or poultry tapeworm.
Correct Answer: Diagnosis is by direct visualisation of characteristic eggs in the stool.
Explanation:Diagnosis of tapeworm is by direct visualisation of characteristic eggs in stool. Humans may be infected by pork or beef tapeworm. Treatment is with praziquantel or niclosamide. Specialist advice should be sought for the management of neurocysticercosis.Iron-deficiency anaemia is typically seen in hookworm infection. Threadworms migrate from the intestine at night to lay eggs on the perianal skin. Mebendazole is first line treatment for threadworms.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 46
Incorrect
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A 26 year old male presents to emergency room with a 2 day history of burning pain when passing urine, accompanied by a green urethral discharge. Gonorrhoea is suspected. The first line antibiotic for this condition is which of the following?
Your Answer: Benzylpenicillin
Correct Answer: Ceftriaxone
Explanation:When there is a high suspicion of gonorrhoea from clinical features, empiric treatment should be commenced whilst waiting for laboratory confirmation. The first line treatment for uncomplicated anogenital and pharyngeal disease includes ceftriaxone 500 mg IM (single dose) + azithromycin 1 g orally as a single dose. This covers concomitant chlamydia infection. For all people who have been treated for gonorrhoea, a test of cure is recommended
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This question is part of the following fields:
- Microbiology
- Pathogens
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