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Question 1
Incorrect
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Which of the following is the most likely causative organism of acute epiglottitis in a 6 year old?
Your Answer: Staphylococcus aureus
Correct Answer: Streptococcus pneumoniae
Explanation:Since the introduction of the HIB vaccine, most cases of acute epiglottitis are now caused by Streptococcus spp. The condition is now rare in children.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 2
Correct
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A patient with abdominal pain, vomiting and bloody diarrhoea develops a low platelet count and deranged renal function. A diagnosis of haemolytic uraemic syndrome is made.
Which of the following organisms is a recognised cause of haemolytic uraemic syndrome? Select ONE answer only.Your Answer: Escherichia coli
Explanation:E.Colistrain 0157 causes enterohaemorrhagic diarrhoea and can be followed by haemolytic uraemic syndrome (renal failure, haemolytic anaemia and thrombocytopenia).
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 3
Correct
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A 38-year-old man returns from an overseas business trip with a fever and a headache. Following investigations a diagnosis of Plasmodium falciparum malaria is made.
Which of the following statements regarding Plasmodium falciparum malaria is true? Select ONE answer only.Your Answer: There may be a continuous fever
Explanation:Plasmodium falciparum malaria is transmitted by female of the Anopheles genus of mosquito. The Aedes genus is responsible for transmitting diseases such as dengue fever and yellow fever.
Plasmodium falciparumis found globally but is mainly found in sub-Saharan Africa.
The incubation period of Plasmodium falciparum malaria is 7-14 days.
Sporozoites invade hepatocytes. Within the hepatocyte asexual reproduction occurs producing merozoites, which are released into the blood stream and invade the red blood cells of the host.
Artesunate is the drug treatment of choice for Plasmodium falciparum malaria. Quinine can still be used where artesunate is not available. Often combination therapy with drugs such as doxycycline or fansidar is also required.
The classic symptom of malaria is the malarial paroxysm, a cyclical occurrence of a cold phase, where the patient experiences intense chills, a hot stage, where the patient feels extremely hot and finally a sweating stage, where the fever declines and the patient sweats profusely. There may also, however, be a continuous fever. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 4
Correct
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A 23-year-old man is discovered to have an infection from Helicobacter pylori.
Which of the following types of cancer is mostly associated with Helicobacter pylori infection?Your Answer: Gastric cancer
Explanation:H. pylori is recognized as a major cause of type B gastritis, a chronic condition formerly associated primarily with stress and chemical irritants. In addition, the strong association between long-term H. pylori infection and gastric cancer has raised more questions regarding the clinical significance of this organism. There is speculation that long-term H. pylori infection resulting in chronic gastritis is an important risk factor for gastric carcinoma resulting in H. pylori being classified as a carcinogen.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 5
Correct
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All of the following statements regarding Helicobacter pylori is considered true, except:
Your Answer: Serum antibody levels should be used to check for successful eradication
Explanation:Helicobacter pylori is a curved, non-spore forming, Gram-negative bacteria that is primarily linked to gastric infections. Once acquired, it colonizes the stomach for a long time and can cause a low-grade inflammatory process, producing a chronic superficial gastritis.
H. pylori can be recovered from gastric biopsy materials. Samples must be transported quickly to the laboratory.
Helicobacter infections usually are identified by nonculture methods. H. pylori can be presumptively identified in a gastric biopsy specimen by testing for the presence of a rapid urease reaction.Serologic testing is an important screening method for the diagnosis of H. pylori infection. It can also be diagnosed by faecal antigen detection, microscopic examination of stained gastric tissue, and DNA amplification tests.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 6
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 7
Correct
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A 29-year-old woman with a skin infection not responding to first-line antibiotics return for a review clinic appointment. The result of her culture shows growth of methicillin-resistant Staphylococcus aureus (MRSA).
Which among the following antibiotics is methicillin-resistant Staphylococcus aureus usually sensitive to?Your Answer: Linezolid
Explanation:Historically, MRSA has been treated successfully with outpatient oral sulphonamides, clindamycin, rifampin, doxycycline, or a combination of these agents. With the development of increasing drug resistance of MRSA to these traditional antimicrobials, there has been a search for more effective antibiotics. One recent study demonstrated that vancomycin, linezolid, and quinupristin-dalfopristin were the most effective antibiotics against multiple strains of MRSA.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 8
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:
Rubella
Roseola infantum (exanthem subitom)
Scarlet fever
Kawasaki disease
Erythema infectiosum (5thdisease)
Enterovirus
Infectious mononucleosis
Diagnosis can be confirmed by the following means:
Salivary swab for measles specific IgM
Serum sample for measles specific IgM
Salivary swab for RNA detection
Possible complications include:
Otitis media
Febrile convulsions
Pneumonia
Bronchiectasis
Diarrhoea
Meningitis
Encephalitis
Immunosuppression
Subacute sclerosing panencephalitis
Death -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 9
Incorrect
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A 41-year-old female patient presents with jaundice. She tells you that she is known to have a chronic hepatitis B infection.
Which of the following hepatitis B serology results is consistent with a patient that is chronically infected? Select ONE answer only.Your Answer: HBsAg positive, anti-HBc positive, IgM anti-HBc positive
Correct Answer: HBsAg positive, anti-HBc positive, IgM anti-HBc negative
Explanation:Hepatitis B surface antigen (HBsAg) is a protein on the surface of the hepatitis B virus, that is the first serologic marker to appear in a new acute infection.It can be detected as early as 1 week and as late as 9 weeks. It can be detected in high levels in serum during acute or chronic hepatitis B virus infection. The presence of HBsAg indicates that the person is infectious. The body normally produces antibodies to HBsAg as part of the normal immune response to infection. HBsAg is the antigen used to make hepatitis B vaccine.
Hepatitis B surface antibody (anti-HBs) indicates recovery and immunity from the hepatitis B virus infection. Anti-HBs also develops in a person who has been successfully vaccinated against hepatitis B.
Total hepatitis B core antibody (anti-HBc): Appears at the onset of symptoms in acute hepatitis B and persists for life. The presence of anti-HBc indicates previous or ongoing infection with hepatitis B virus in an undefined time frame. It is not present following hepatitis B vaccination.
IgM antibody to hepatitis B core antigen (IgM anti-HBc) indicates recent infection with hepatitis B virus (<6 months). Its presence indicates acute infection.
The following table summarises the presence of hepatitis B markers according to each situation:
Susceptible to infection:
HBsAg = Negative
Anti-HBc = Negative
Anti-HBs = NegativeImmune due to natural infection:
HBsAg = Negative
Anti-HBc = Positive
Anti-HBs = PositiveImmune due to vaccination:
HBsAg = Negative
Anti-HBc = Negative
Anti-HBs = PositiveAcute infection:
HBsAg = Positive
Anti-HBc = Positive
Anti-HBs = Negative
IgM anti-HBc = PositiveChronic infection:
HBsAg = Positive
Anti-HBc = Positive
Anti-HBs = Negative
IgM anti-HBc = Negative -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 10
Incorrect
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A 56-year-old man presents with pneumonia 8 days after being admitted for an open fracture of his tibia and fibula. Upon history taking and observation, it was established that he has no known drug allergies, has coarse left basal crackles and evidence of consolidation in the left lower lobe based on his chest X-ray.
Which of the following antibacterial agents would be the most appropriate to prescribe according to the latest NICE guidelines?Your Answer: Co-amoxiclav
Correct Answer: Ciprofloxacin
Explanation:The current NICE guidelines for hospital-acquired pneumonia are as follow:
– First-choice oral antibiotic if non‑severe symptoms or signs, and not at higher risk of resistance (guided by microbiological results when available): co-amoxiclav– Alternative oral antibiotics if non‑severe symptoms or signs, and not at higher risk of resistance, for penicillin allergy or if co‑amoxiclav unsuitable (based on specialist microbiological advice and local resistance data): doxycycline, cefalexin, co-trimoxazole, levofloxacin
– First-choice intravenous antibiotics if severe symptoms or signs (for example, symptoms or signs of sepsis) or at higher risk of resistance (based on specialist microbiological advice and local resistance data): piperacillin with tazobactam, ceftazidime, ceftriaxone, cefuroxime, meropenem, ceftazidime with avibactam, levofloxacin
– Antibiotics to be added if suspected or confirmed methicillin-resistant Staphylococcus aureus infection (dual therapy with a first-choice intravenous antibiotic): vancomycin, teicoplanin, linezolid
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 11
Correct
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A mother has serious concerns about vaccinating her child. She has read about many contraindications and risks in the papers and would like to discuss them with you.
One of these is a valid contraindication to vaccination.
Your Answer: None of the other options
Explanation:The options listed in this question are not true contraindications to vaccination. Therefore, the correct answer is ‘none of the other options’.
The contraindications to vaccination are:
Confirmed anaphylactic reaction to a previous dose of the vaccine or a vaccine containing the same antigens.
A confirmed anaphylactic reaction to another component in the vaccine. -
This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 12
Correct
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You see a patient in the ED with photophobia, petechial rash, headache and neck stiffness, and suspect a diagnosis of meningococcal meningitis.
What is the most appropriate initial management?
Your Answer: Give ceftriaxone 2 g IV
Explanation:Treatment should be commenced with antibiotics immediately before laboratory confirmation due to the potentially life-threatening nature of the disease.
In a hospital setting, 2g of IV ceftriaxone (80 mg/kg for a child) or IV cefotaxime (2 g adult; 80 mg/kg child) are the drugs of choice.
In the prehospital setting, IM benzylpenicillin can be given as an alternative. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 13
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 14
Correct
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Which of the following serology results is consistent with chronic hepatitis B infection:
Your 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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Question 15
Correct
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Question 16
Incorrect
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A 35-year-old man is feeling unwell following his return from a business trip. He is diagnosed with a vector transmitted disease.
Which of these organisms is commonly spread by vector-borne transmission?Your Answer: Vibrio cholerae
Correct Answer: Borrelia burgdorferi
Explanation:Borrelia burgdorferiis, primarily spread by ticks and lice, is a zoonotic, vector-borne organism that causes Lyme disease.
Neisseria meningitidis and Bordetella pertussis are droplet borne infections (airborne particle > 5 µm)
Vibrio cholerae and Ascaris lumbricoides are spread by the faeco-oral route
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 17
Correct
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A patient with a wound infection on his right leg has reddening and oedema of the surrounding muscles. His condition has worsened considerably over the past few hours with the area now appearing blackened. There is also palpable crepitus under the skin. You suspect gas gangrene.
Which statement about Clostridium perfringens is true?Your Answer: Gas gangrene is caused by the release of an alpha-toxin
Explanation:Clostridium perfringens, a Gram-positive, anaerobic, spore forming rod-shaped, pathogenic bacterium is the most commonly associated with gas gangrene (85-90% of cases), although other species can also be implicated.
Clostridium perfringens is capsulate and produces a range of toxins. Alpha-toxin is the most important and is the cause of gas gangrene.
Gas gangrene develops when a devitalized wound becomes infected with Clostridium perfringens spores from the environment. The spores germinate and multiplies in the ischaemic conditions, releasing toxins, which further damage tissues.
Usually, the clinical features of gas gangrene appear within 24 hours of injury.
Clostridium perfringens spores are not destroyed by cooking. During slow cooling and unrefrigerated storage, they germinate to form vegetative cells.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 18
Correct
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A 33-year-old female, who recently returned from a trip to Bangladesh, presents to the infectious diseases clinic with complaints of productive cough with blood-stained sputum, night sweats, and weight loss for the past one month. Based on the history and examination findings, you suspect pulmonary tuberculosis.
Which ONE of the following investigations is most appropriate to make a diagnosis of active tuberculosis?Your Answer: Sputum for acid-fast bacilli smear
Explanation:Multiple investigations may be done to establish a diagnosis of active tuberculosis. In this case, sputum for acid-fast bacilli would be the best option as it can be done immediately, give fast results, and promptly initiate treatment. Three-morning sputum samples are collected and tested for acid-fast bacilli using gram staining.
Blood culture would yield results in tuberculous bacteraemia and would be less sensitive than sputum testing.
A chest X-ray would not differentiate active tuberculosis from an old infection in which the Ghon complex has formed, and the body’s immune reaction contains the Mycobacterium tuberculosis bacteria.
Mantoux test shows the presence of antibodies to tuberculosis and may be positive if the patient has had a previous infection or been vaccinated against tuberculosis.
A CT chest would also be unable to differentiate between an active infection and the findings of old tuberculosis infection.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 19
Correct
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The monospot test for infectious mononucleosis uses which of the following types of red blood cell?
Your Answer: Horse red blood cells
Explanation:Infectious mononucleosis can be diagnosed using specific EBV antibodies and a variety if unrelated non-EBV heterophile antibodies. These antibodies can be detected by two main screening tests:
The monospot test uses horse red blood cells. It agglutinates in the presence of heterophile antibodies.
Sheep red blood cells is used in Paul-Bunnell test. The blood agglutinates in the presence of heterophile antibodies.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 20
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 21
Correct
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The most common source of healthcare-associated bacteraemia is:
Your Answer: Intravenous cannula
Explanation:Healthcare-associated bacteraemia is most commonly caused by intravenous access. Any intravenous device that is left in place for a long time increases the risk of infection. It allows bacteria like Staphylococcus aureus and Staphylococcus epidermidis to enter the body.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 22
Incorrect
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A 35-year-old man presents with haemoptysis, night sweats, and weight loss. Further examinations were done and a diagnosis of tuberculosis is suspected.
Which of the following statements is considered correct regarding Mycobacterium tuberculosis?Your Answer: The Ghon focus typically appears at the base of the lower lobe of the lung
Correct Answer: It is impervious to decolourisation with acid
Explanation:Mycobacterium tuberculosis are part of the Mycobacteriaceae family. They are described to have the characteristics of a Gram-positive cell wall but they are not easily stained with Gram stain. This is because their cell wall contains a high lipid content, and this lipid allows the Mycobacteria to bind to alkaline stains with the application and help of heat. Once stained, they are able to resist decolorization even with the use of acid alcohol as the decolourizer, making them very difficult to decolorize, that is why they are known to be acid-fast.
The Ghon complex is a non-pathognomonic radiographic finding on a chest x-ray that is significant for pulmonary infection of tuberculosis. The location of the Ghon’s focus is usually subpleural and predominantly in the upper part of the lower lobe and lower part of the middle or upper lobe.
Skeletal tuberculosis of the spine is referred to as Pott disease.
The risk of reactivation TB is about 3.3% during the first year after a positive PPD skin test and a total of 5% to 15% thereafter in the person’s lifetime. Progression from infection to active disease varies with age and the intensity and duration of exposure. Reactivation TB occurs when there is an alteration or suppression of the cellular immune system in the infected host that favours
replication of the bacilli and progression to disease. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 23
Correct
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Regarding bronchiolitis, which of the following statements is CORRECT:
Your Answer: Chest x-ray may show hyperinflation and increased peribronchial markings.
Explanation:Acute bronchiolitis is caused most commonly by respiratory syncytial virus, occurring mostly in children aged 6 months to 2 years. Children with bronchiolitis are febrile and tachypnoeic with a dry cough and difficulty feeding. Examination may reveal chest hyperinflation, respiratory distress, wheezing and fine end-inspiratory crepitations. Chest x-ray may show hyperinflation and increased peribronchial markings (although CXR should only performed if there is diagnostic uncertainty or an atypical course). Treatment is usually supportive, aerosolized ribavirin is reserved for severely ill or immunocompromised patients.
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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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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: 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 25
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 26
Correct
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A 42-year-old man presented to the emergency room with complains of a dry cough and fever that has been going on for the past few days. Upon history taking and observation, it was established that he works as a Jacuzzi and whirlpool installer and smokes 15 cigarettes per day. The presence of a non-productive cough, several episodes of diarrhoea, developed bilateral pleuritic chest pain, and shortness of breath most notably on exertion were also noted.
Which of the following is most likely the causative agent of the case presented above?Your Answer: Legionella pneumophila
Explanation:Legionella species are ubiquitous, Gram-negative bacilli acquired primarily through inhalation. Infections caused by Legionella spp. produce a spectrum of symptoms ranging from mild upper respiratory tract infections to pneumonia. Legionella spp. are responsible for 2% to 15% of community-acquired pneumonia.
Clinical manifestations of Legionella infections include febrile disease with pneumonia (legionnaires’ disease), febrile disease without pulmonary involvement (Pontiac fever), and asymptomatic infection.
The mode of transmission and the number of infecting organisms in the inoculum play a role in the clinical features of the infection. In addition, host factors, such as a suppressed immune system, chronic lung disease, alcoholism, and heavy smoking, predispose individuals to legionnaires’ disease.Legionella spp. can tolerate chlorine concentrations of 3 mg/L, they resist water treatment and subsequently gain entry into and colonize human-made water supplies and distribution systems. Hot water systems, cooling towers, and evaporative condensers are major reservoirs. Other sources include cold water systems, ornamental fountains, whirlpool spas, humidifiers, respiratory
therapy equipment, and industrial process waters. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 27
Incorrect
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In adults in the United Kingdom, which of the following pathogens is the most likely cause of viral infectious gastroenteritis:
Your Answer: Rotavirus
Correct Answer: Norovirus
Explanation:Norovirus is the most common viral cause of epidemic gastroenteritis worldwide; it is also a common cause of endemic diarrhoea in community settings. In the United Kingdom, norovirus has become the most common cause of gastroenteritis in adults and children since the introduction of rotavirus vaccination.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 28
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 29
Incorrect
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The causative organism for an infection in a patient you are reviewing is a facultative anaerobe.
Which of these is a facultative anaerobic organism?Your Answer: Campylobacter jejuni
Correct Answer: Staphylococcus aureus
Explanation:Facultative anaerobic bacteria make energy in the form of ATP by aerobic respiration in an oxygen rich environment and can switch to fermentation in an oxygen poor environment.
Examples of facultative anaerobes are:
Staphylococcus spp.
Listeria spp.
Streptococcus spp.
Escherichia coliMycobacterium tuberculosis, and Pseudomonas aeruginosa are obligate aerobe. They require oxygen to grow
Campylobacter jejuni and Clostridium spp are obligate anaerobes.
They live and grow in the absence of oxygen. -
This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 30
Correct
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Which of the following is NOT a typical complication associated with mumps:
Your 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 31
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 32
Incorrect
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A 29-year-old male presents with a 3-day history of bloody diarrhoea and abdominal pain.
All the following are causes of infectious bloody diarrhoea EXCEPT?
Your Answer: Campylobacter jejuni
Correct Answer: Enterotoxigenic Escherichia coli
Explanation:Infective causes of bloody diarrhoea include:
Salmonella spp
Campylobacter spp
Schistosomiasis
Entamoeba histolytica (Amoebiasis )
Shigella spp
Clostridium difficile
Yersinia spp
Enteroinvasive Escherichia coliEnterotoxigenic Escherichia coli is non-invasive and does not cause inflammation of the gut and bloody diarrhoea. It presents with copious watery diarrhoea and usually are not associated with abdominal cramping.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 33
Correct
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Which of the following bacteria is a rod-shaped, oxidase-positive, opportunistic gram-negative bacteria that can cause a catheter-related urinary tract infection (UTI)?
Your Answer: Pseudomonas aeruginosa
Explanation:Listeria monocytogenes is a gram-positive bacteria that does not produce spores.
Staphylococcus aureus is a gram-positive bacteria, while Candida albicans is a gram-positive yeast with a single bud.
Among the choices, gram-negative bacteria include only Klebsiella pneumoniae and Pseudomonas aeruginosa.
Pseudomonas aeruginosa is an oxidase-positive bacterium, while Klebsiella pneumoniae is an oxidase-negative bacterium.
P. aeruginosa can cause urinary tract infections (UTIs) and is spread through poor hygiene or contaminated medical equipment or devices, such as catheters that haven’t been fully sterilized.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 34
Correct
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A 70-year-old patient develops bacteraemia following peripheral cannulation.
Which of these bacteria is the most likely cause of the infection?Your Answer: Staphylococcus epidermidis
Explanation:The commonest implicated organisms in hospital-acquired bacteraemia following cannulation are Staphylococcus aureus and Staphylococcus epidermidis.
The risk is directly proportional to the length of time in-situ. Peripheral cannula should be replaced after 48 hours. -
This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 35
Correct
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Regarding control of hospital acquired infection (HAI), which of the following statements is CORRECT:
Your Answer: Chlorhexidine is an anti-staphylococcal agent.
Explanation:Chlorhexidine is an anti-staphylococcal agent. Cleaning is the removal of foreign material from areas or objects to a point at which they are visually free from debris.  Disinfection is the reduction in the number of infectious particles. Isopropyl alcohol is not effective against C. difficile spores. Autoclaving is a method of sterilisation.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 36
Correct
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A young man develops an infection spread via aerosol transmission.
Which of these organisms is commonly spread by aerosol transmission?Your Answer: Measles virus
Explanation:Aerosols are airborne particles less than 5 µm in size, containing infective organisms that usually cause infection of the upper or lower respiratory tract.
Examples of organisms commonly spread by aerosol transmission are:
Measles virus
Varicella zoster virus
Mycobacterium tuberculosisThe following table summarises the various routes of transmission with example organisms:
Route of transmission
Example organisms
Aerosol (airborne particle < 5 µm)
Mycobacterium tuberculosis
Varicella zoster virus
Measles virusHepatitis A and Rotavirus are spread by the faeco-oral route.
Neisseria gonorrhoea is spread by sexual route.
Staphylococcus aureus is spread by direct contact.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 37
Correct
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A 20-year-old male patient lives in a travelling community and has never received any vaccinations. He presents to you with fever.
Which of these statements concerning indications and contraindications for vaccination is FALSE?
Your Answer: Premature infants should have the their immunisation schedule adjusted for gestational age
Explanation:All vaccines are contraindicated in individuals with:
A confirmed anaphylactic reaction to a previous dose of the vaccine or a vaccine containing the same antigens.
A confirmed anaphylactic reaction to a component in the vaccine e.g. neomycinLive attenuated vaccines are contraindicated in pregnancy except in cases where risk of infection is more than the risks of vaccination.
During times of acute febrile illness, vaccination should be avoided.
12 weeks should elapse after a dose of human immunoglobulin before a live vaccine is administered.
The normal times recommended for immunization of full-term babies should also be applied to premature infants and correction for gestational age should NOT be implemented.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 38
Correct
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Aldin is a 24-year-old male patient who arrives at the emergency department diagnosed with psittacosis based on his symptoms and history of being a pigeon enthusiast. Which of the following is the causative bacteria of psittacosis?
Your Answer: Chlamydia psittaci
Explanation:Chlamydia psittaci is a microorganism that is commonly found in birds.
These bacteria can infect people and cause psittacosis. Psittacosis is an infectious disease that may cause high fever and pneumonia associated with headaches, altered mental state, and hepatosplenomegaly.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 39
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 40
Correct
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Regarding Cryptococcus neoformans, which of the following statements is INCORRECT:
Your Answer: Patients with complement deficiency are at particular risk of infection.
Explanation:Cryptococcus neoformans typically causes infection in patients with lymphoma, those taking steroid or cytotoxic therapy, those with T-cell deficiency e.g. AIDS and those with intense exposure, such as pigeon fanciers.
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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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A 22 year old student has recently returned from travelling around Kenya and presents to ED with a headache and persistent fever. Malaria is being considered as a potential diagnosis. Which of the following strains of malaria is most likely:
Your Answer: Plasmodium falciparum
Explanation:Malaria is an infectious disease transmitted by female of theAnophelesgenus of mosquito. It is a parasitic infection caused by the genusPlasmodium. Five species are recognized as causing disease in humans;Plasmodium falciparum,Plasmodium ovale,Plasmodium vivax,Plasmodium malariaeandPlasmodium knowlesi.
The classic symptom of malaria is the malarial paroxysm, a cyclical occurrence of a cold phase, where the patient experiences intense chills, a hot stage, where the patient feels extremely hot and finally a sweating stage, where the fever declines and the patient sweats profusely. On examination the patient may show signs of anaemia, jaundice and have hepatosplenomegaly without evidence of lymphadenopathy.Plasmodium falciparum is the most serious form and is responsible for most deaths. Severe or complicated malaria is suggested by the presence of impaired consciousness, seizures, hypoglycaemia, anaemia, renal impairment, respiratory distress and spontaneous bleeding.
Plasmodium falciparum is the most likely type in this case in view of the presentation.
Haemoglobinuria and renal failure following treatment is suggestive of blackwater fever, which is caused byPlasmodium falciparum. An autoimmune reaction between the parasite and quinine causes haemolysis, haemoglobinuria, jaundice and renal failure. This can be fatal.
The benign malarias: P.vivax, P. malariae and P.ovale are usually treated with chloroquine. A course of primaquine is also required in P.vivax and P.ovale infection. Artesunate is the drug treatment of choice for Plasmodium falciparum malaria. Quinine can still be used where artesunate is not available. Often combination therapy with drugs such as doxycycline or fansidar is also required. -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 42
Correct
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The percentage of patients with hepatitis B that develop chronic infection is about:
Your 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 43
Correct
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A blood culture was performed from a sample taken from a patient. It was noted that a Gram-negative coccus organism was grown.
Among the following microorganisms, which is considered an example of a Gram-negative coccus?Your Answer: Neisseria menigitidis
Explanation:Staphylococcus aureus = Gram-positive coccus
Bacillus cereus = Gram-positive bacillus
Campylobacter jejuni = Gram-negative bacillus
Escherichia coli = Gram-negative bacillusIn Gram staining, crystal violet is a purple stain that is used to stain the bacteria first. The stained bacteria are decolorized and then stained with a red stain, which is safranin. Bacteria with thick cell walls keep the purple stain and are called Gram-positive. Thin-walled bacteria are easily decolorized so when safranin, the red stain, is placed on the organisms, they become red or Gram-negative.
Neisseria species appear as Gram-negative diplococci because they form pairs and their adjacent ends are flattened that is why they are also described to have a coffee-bean or kidney-bean shape. -
This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 44
Correct
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On his stool culture, a patient with a diarrhoeal illness grows Escherichia coli.
What SINGLE statement about Escherichia coli is true?
Your Answer: Most serotypes are harmless
Explanation:Escherichia coli is a Gram-negative, non-spore forming, facultative anaerobic, rod-shaped bacterium.
Although some can cause serious food poisoning, most serotypes are harmless.
Escherichia coli is transmitted via the faeco-oral route.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 45
Incorrect
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A 55-year-old woman with history of gastritis and reflux esophagitis tested positive for Helicobacter pylori infection.
Which of the following statements regarding Helicobacter pylori is considered true?Your Answer: It is non-motile
Correct Answer: It is helix shaped
Explanation:Helicobacter pylori is a curved or helix-shaped, non-spore forming, Gram-negative, microaerophilic bacteria. It is motile, having multiple flagella at one pole. It has a lipopolysaccharide component in its outer membrane.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 46
Correct
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A diagnosis of acute osteomyelitis was made on a patient with a known history of sickle cell disease. He has no joint prosthesis on in-dwelling metal work and no known drug allergies.
Which of the following is most likely the causative agent of the case presented above?Your Answer: Salmonella spp .
Explanation:Patients with sickle cell disease are prone to infection of the bone and bone marrow in areas of infarction and necrosis. Although Staphylococcus aureus is the most common cause of osteomyelitis in the general population, studies have shown that in patients with sickle cell disease, the relative incidence of Salmonella osteomyelitis is twice that of staphylococcal infection.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 47
Correct
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A 10-year-old girl that appears systemically well presents with a honey-crusted scab close to the corner of her mouth and states that the area is slightly itchy but not painful. The diagnosis given was impetigo.
What is most likely the mode of transmission of the causative agent of the said diagnosis?Your Answer: Direct contact
Explanation:Impetigo is a common pyoderma that is most often seen in children. Historically, most cases were caused by group A streptococci (GAS; Streptococcus pyogenes), although S. aureus has become the predominant pathogen over the last 15 years.
A bullous form of impetigo accounts for approximately 10% of cases. It is caused by strains of S. aureus that produce exfoliative toxins leading to the formation of bullae, which quickly rupture and form a transparent, light brown crust.
Impetigo is spread mainly by person-to-person contact; it is rapidly spread through direct transmission. The diagnosis of impetigo can be made from a Gram stain and culture of the vesicular contents.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 48
Correct
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A 71-year-old woman is treated with co-amoxiclav for a chest infection but she returns 1 week later. Her chest infection has resolved but she developed a profuse, offensive smelling diarrhoea and abdominal cramps. You suspect Clostridium difficile associated diarrhoea (CDAD).
ONE of these statements is true concerning this diagnosis.Your Answer: The gold standard for the diagnosis of Clostridium difficile colitis is cytotoxin assay
Explanation:Clostridium difficile, a Gram-positive, anaerobic, spore forming bacteria is present in the gut of approximately 3% of healthy adults (2012 UK HPA estimates). Following use of broad spectrum antibiotics, which alter normal gut flora, Clostridium difficile associated diarrhoea (CDAD) occurs.
Alcohol hand gel is not effective against Clostridium Difficile spores. Hand washing with soap and water is very essential for healthcare workers who come in contact with it.
Currently, the gold standard for the diagnosis of Clostridium difficile colitis is cytotoxin assay. Stool culture to detect Clostridium difficile is not specific for pathogenic strains, is expensive and therefore not specific for a diagnosis of CDAD
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 49
Correct
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In a 7-year-old child with chickenpox, which of the following would you advise the mother NOT to do?
Your Answer: Give ibuprofen for the fever
Explanation:Chickenpox (varicella zoster) is a highly contagious airborne disease and has an incubation period of between 7-21 days. It often has a prodromal phase when there is a fever, aches and headaches, dry cough, and sore throat before onset of rash.
Some recognized complications of chickenpox are:
Orchitis
Hepatitis
Pneumonia
Encephalitis
Infected spots
Otitis media
Myocarditis
Glomerulonephritis
Appendicitis
PancreatitisTreatment is symptomatic and includes using paracetamol to manage fever. There is a link between use of ibuprofen in patients with chicken-pox and necrotizing fasciitis so Ibuprofen should NOT be used.
An emollient and antihistamine can be used to ease the itchy rash and oral hydration is encouraged.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 50
Correct
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A 20-year-old male patient lives in a travelling community and has never received any vaccinations. He presents to you with fever.
Which of these statements concerning indications and contraindications for vaccination is TRUE?
Your Answer: Inactivated vaccines are safe in pregnancy
Explanation:All vaccines are contraindicated in individuals with: A confirmed anaphylactic reaction to a previous dose of the vaccine or a vaccine containing the same antigens.
A confirmed anaphylactic reaction to a component in the vaccine e.g. neomycinThere is no evidence that vaccinating pregnant women with inactivated vaccine or toxoids harms the woman or foetus.
The current protocol is that a child with history of egg allergy can be safely vaccinated with Fluenz tetra. However, if they had a previous severe anaphylaxis to egg requiring intensive care, then Flenz tetra is contraindicated.
BCG, yellow fever or oral typhoid vaccinations are not safe in HIV positive patients.
The normal times recommended for immunization of full-term babies should also be applied to premature infants and correction for gestational age should not be implemented.
Concurrent antibiotic therapy is not a contraindication to vaccination.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
