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Question 1
Correct
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Which of the following is diagnostic for acute hepatitis B infection:
Your 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 2
Correct
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Cryptococcus neoformans is primarily implicated in which of the following conditions:
Your Answer: Chronic lymphocytic meningitis
Explanation:Cryptococcus neoformans typically causes a chronic lymphocytic meningitis in immunosuppressed patients or those with intense exposure e.g. pigeon fanciers.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 3
Correct
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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: 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 4
Correct
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A 71-year-old man treated with antibiotics for a chest infection returns with a profuse, offensive smelling diarrhoea. A diagnosis of Clostridium difficile diarrhoea is made after investigations.
Which antibiotic is associated with the greatest risk of causing Clostridium Difficile diarrhoea?
Your Answer: Ciprofloxacin
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 infection (CDI) occurs. About 80% of Clostridium Difficile infections are seen in people over the age of 65 and its main clinical features are:
Abdominal cramps, severe bloody and/or watery diarrhoea, offensive smelling diarrhoea, and fever.CDI is the most severe consequence of antibiotic treatment and is a major cause of morbidity and mortality.
Risk for CDI has been found to be greatest with clindamycin followed by fluoroquinolones Tetracyclines are not associated with risk for CDI. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 5
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 6
Correct
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A 30-year-old male farmer presents to the Emergency Department due to a wound on his right forearm sustained two days ago while working on the farm. He cleaned the wound under a tap, but there was still some dirt and debris on examination.
Past medical history reveals that he never received a tetanus vaccine.
After cleaning the wound and prescribing antibiotics, which ONE of the following actions should be taken to manage his tetanus risk?Your Answer: Tetanus vaccination and 500 IU tetanus immunoglobulin
Explanation:If a patient presents with one of the following types of wounds, they are at risk of contracting tetanus and should be vaccinated immediately:
1) Contaminated puncture-type wounds from gardening and farming (as they may contain tetanus spores)
2) Wounds containing foreign bodies
3) Open (compound) fractures
4) Wounds or burns with sepsis
5) Animal bites and scratches (animal saliva does not contain tetanus spores unless the animal was routing in soil or lives in an agriculture setting)Extremely high-risk tetanus-prone wounds are any of the above wounds with one of the following:
1) Any wound contaminated by materials containing tetanus spores, e.g., soil, manure
2) Burns or wounds with extensive devitalised tissue
3) Wounds or burns with surgical intervention delayed for more than six hours even if the initial injury was not heavily contaminatedThe CDC recommends that adults who have never been vaccinated for tetanus receive a quick shot of the tetanus vaccine along with a booster dose ten years later. A tetanus-prone wound in an unvaccinated individual should also receive a high dose of tetanus immunoglobulin. The injected antibodies will prevent tetanus infection as the patient does not have any pre-existing antibodies against the disease.
In this case, the patient has a high risk, contaminated wound. He should receive a high dose of tetanus immunoglobulin along with the tetanus vaccine. (The preventative dose of tetanus immunoglobulin is 250 IU in most cases unless over 24 hours have passed since the injury or the wound is heavily contaminated, then 500 IU should be given.) His physician also needs to be contacted to arrange the remainder of the course as indicated in this case.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 7
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 8
Incorrect
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One of the following pathogens is a conditional pathogen:
Your Answer: Treponema pallidum
Correct Answer: Neisseria meningitidis
Explanation:Obligate pathogens include Mycobacterium TB, HIV, Treponema pallidum, and Neisseria gonorrhoeae. Neisseria meningitidis, on the other hand, is a conditional pathogen.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 9
Correct
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Clostridium tetani causes which of the following infectious diseases:
Your Answer: Tetanus
Explanation:Clostridium tetani causes tetanus.
Scarlet fever is caused by Streptococcus pyogenes.
Toxic shock syndrome is caused by Staphylococcus aureus or Streptococcus pyogenes.
Gas gangrene is primarily caused by Clostridium perfringens.
Pseudomembranous colitis is commonly caused by Clostridium difficile. -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 10
Incorrect
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Regarding Clostridium difficile, which of the following statements is CORRECT:
Your Answer: It has endotoxin-mediated effects causing profuse watery diarrhoea.
Correct 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 11
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 12
Incorrect
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A 52-year-old man develops pneumonia 3 days following an admission for investigation of chest pain. He has coarse left basal crackles and evidence of consolidation in the left lower lobe of chest X-ray. He has no known drug allergies.
According to the latest NICE guidelines, which of the following antibacterial agents would be most appropriate to prescribe in this case? Select ONE answer only.Your Answer: Ciprofloxacin
Correct Answer: Co-amoxiclav
Explanation:Nosocomial infections are defined as those occurring within 48 hours of hospital admission, 3 days of discharge or 30 days of an operation. They affect 1 in 10 patients admitted to hospital. Annually, this results in 5000 deaths with a cost to the National Health Service of a billion pounds. On average, a patient with hospital acquired infection spent 2.5-times longer in hospital, incurring additional costs of £3000 more than an uninfected patient. Intensive care units (ICU) have the highest prevalence of hospital-acquired infections in the hospital setting.
The current recommendations by NICE and the BNF on the treatment of hospital acquired pneumonia are:
Early onset infection(less than 5 days after admission to hospital): co-amoxiclav or cefuroxime for 7 days
Late-onset infection(more than 5 days after admission to hospital): an antipseudomonal penicillin (e.g. piperacillin with tazobactam), a broad-spectrum cephalosporin (e.g. ceftazidime), or a quinolone (e.g. ciprofloxacin)
If the patient developed a hospital-acquired pneumonia within 5 days of admission – co-amoxiclav would be the most appropriate choice.
If the patient has developed a hospital-acquired pneumonia > 5 days after admission – ciprofloxacin would be the most appropriate choice from the list of options available. -
This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 13
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 14
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 15
Correct
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Which of the following pathogens is the common cause of diarrhoea in a patient who has had a prolonged course of a broad spectrum of antibiotics?
Your Answer: Clostridium difficile
Explanation:Clostridium difficile is the most likely cause of diarrhoea after a long course of broad-spectrum antibiotic treatment.
Clostridium difficile-associated diarrhoea appeared to be linked to an increase in the usage of third-generation cephalosporins.
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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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After reviewing a child with respiratory distress who presented to the clinic, you make a diagnosis of bronchiolitis.
What is the most common causative organism?
Your Answer: Parainfluenza virus type 1
Correct Answer: Respiratory syncitial virus
Explanation:Bronchiolitis is a common respiratory infection that occurs in infancy between the ages of 3-6 months and in the winter months. It is most commonly caused by the respiratory syncytial virus (70% of cases)
Although it can also be caused by parainfluenza virus, adenovirus, coronavirus, rhinovirus, and influenza virus, these are not the most common causes
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 17
Incorrect
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A 7-days-old neonate is taken to the emergency department. She's pyretic, lethargic, and unresponsive, and her fontanelle has bulged. Antibiotics are started, and a lumbar puncture reveals Gram-negative rods. Which pathogen is most likely to be the cause:
Your Answer: Haemophilus influenzae
Correct Answer: Escherichia coli
Explanation:Among neonates, group B streptococci (GBS) are the most commonly identified causes of bacterial meningitis, implicated in roughly 50% of all cases. Escherichia coli(Gram-negative rods) accounts for another 20%. Thus, the identification and treatment of maternal genitourinary infections is an important prevention strategy.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 18
Correct
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Clostridium difficile primarily causes which of the following infectious diseases:
Your Answer: Pseudomembranous colitis
Explanation:Clostridium difficile causes pseudomembranous colitis, an acute inflammatory diarrhoeal disease and an important cause of morbidity and mortality in hospitals. Gas gangrene is primarily caused by Clostridium perfringens. Tetanus is caused by Clostridium tetani. Toxic shock syndrome may be caused by Staphylococcus aureus or Streptococcus pyogenes. Necrotising fasciitis is most commonly caused by Streptococcus pyogenes but has a multitude of causes.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 19
Correct
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Among the following infectious diseases, which is typically considered to have an incubation period of 3 weeks and longer?
Your Answer: Infectious mononucleosis
Explanation:Infectious mononucleosis is caused by Epstein-Barr virus (EBV). The incubation period for EBV varies from 2 weeks to 2 months.
The usual incubation period for rubella is 14 days; with a range of 12 to 23 days.
Gonorrhoea has a short incubation period of approximately 2 to 7 days.
The mumps virus can be isolated from infected saliva and swabs rubbed over the Stensen’s duct from 9 days before onset of symptoms until 8 days after parotitis appears.
Scarlet fever, which appears within 1 to 2 days after bacterial infection, is characterized by a diffuse red rash that appears on the upper chest and spreads to the trunk and extremities. The rash disappears over the next 5 to
7 days and is followed by desquamation. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 20
Incorrect
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Anatomical barriers to infection include all of the following EXCEPT:
Your Answer: Commensal flora in the genitourinary tract
Correct Answer: Mucociliary escalator in the gastrointestinal tract
Explanation:Anatomical barriers to infection include:tight junctions between cells of the skin and mucosal membranesthe flushing action of tears, saliva and urinethe mucociliary escalator in the respiratory tract (together with the actions of coughing and sneezing)the acidic pH of gastric and vaginal secretionsthe acidic pH of the skin (maintained by lactic acid and fatty acids in sebum)enzymes such as lysozyme found in saliva, sweat and tearspepsin present in the stomachbiological commensal flora formed on the skin and the respiratory, gastrointestinal and genitourinary tracts which protect the host by competing with pathogenic bacteria for nutrients and attachment sites and by producing antibacterial substances
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This question is part of the following fields:
- Microbiology
- Principles
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Question 21
Correct
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Which of the following is the most likely causative organism of acute epiglottitis in a 6 year old?
Your 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 22
Correct
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A patient with a central line in situ for the past 10 days now has erythema surrounding the catheter insertion site and shows signs of sepsis. You suspect line sepsis.
Which of these antibacterial agents would be most appropriate to prescribe for this patient?Your Answer: Vancomycin
Explanation:The current recommendation by NICE and the BNF is to use vancomycin as first-line in treatment of septicaemia related to vascular catheter. A broad-spectrum antipseudomonal beta-lactam antibiotic should be added to vancomycin if a Gram-negative sepsis is suspected especially in an immunocompromised patient.
In any patient that has had a central venous catheter in situ for a period longer than a week, it should be suspected as the source of sepsis.
The features suggesting the vascular catheter as the source of infection include:
Presence of the catheter before onset of fever.
The absence of another identifiable source of infection.
Presence of inflammation or purulent material at the insertion site or along the tunnel.
An immunocompetent patient without any underlying disease developing bacteraemia (or fungaemia). -
This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 23
Incorrect
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Which statement concerning aerosol transmission is true?
Your Answer:
Correct Answer: They can be spread via ventilation systems in hospitals
Explanation:Aerosols are airborne particles less than 5 µm in size containing infective organisms.
They usually cause infection of both the upper and/or lower respiratory tract.
The organisms can remain suspended in the air for long periods and also survive outside the body.
They can be transmitted through the ventilation systems and can spread over great distances.
Some examples of organisms transmitted by the aerosol route include: Varicella zoster virus, Mycobacterium tuberculosis and measles virus
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 24
Incorrect
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Regarding threadworms, which of the following statements is CORRECT:
Your Answer:
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 25
Incorrect
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A 26-year-old woman is currently 9 weeks pregnant. Upon interview and history taking, she mentioned that she visited a friend whose child had just been diagnosed with slapped cheek disease.
If the mother contracts an illness during pregnancy, which among the following is not known to cause fetal abnormalities?Your Answer:
Correct Answer: Hepatitis A
Explanation:Hepatitis A usually doesn’t pose a special risk to a pregnant woman or her baby. Maternal infection doesn’t result in birth defects, and a mother typically doesn’t transmit the infection to her baby. HAV is almost always transmitted by the faecal-oral route and is usually acquired through close personal contact or via contaminated food.
When a woman has chickenpox in the first 20 weeks of pregnancy, there is a 1 in 50 chance for the baby to develop a set of birth defects. This is called the congenital varicella syndrome. It includes scars, defects of muscle and bone, malformed and paralyzed limbs, small head size, blindness, seizures, and intellectual disability.
TORCH Syndrome refers to infection of a developing foetus or newborn by any of a group of infectious agents. “TORCH” is an acronym meaning (T)toxoplasmosis, (O)ther Agents, (R)ubella (also known as German Measles), (C)ytomegalovirus, and (H)erpes Simplex.
Infection with any of these agents may cause a constellation of similar symptoms in affected newborns. These may include fever; difficulties feeding; small areas of bleeding under the skin, causing the appearance of small reddish or purplish spots; enlargement of the liver and spleen (hepatosplenomegaly); yellowish discoloration of the skin, whites of the eyes, and mucous membranes (jaundice); hearing impairment; abnormalities of the eyes; and other symptoms and findings. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 26
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:
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 27
Incorrect
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Red cell protein expression is induced by which of the following pathogens:
Your Answer:
Correct Answer: Plasmodium falciparum
Explanation:Plasmodium falciparum induces the expression of red cell protein, making cerebral malaria more severe. Bacteria may invade a host passively through micro traumata or macro traumata in the skin or mucosa. On the other hand, bacteria that invade
through intact mucosa first, adhere to this anatomical barrier, then actively
breach it. -
This question is part of the following fields:
- Microbiology
- Principles
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Question 28
Incorrect
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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:
Correct 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 29
Incorrect
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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:
Correct 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 30
Incorrect
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A 19-year-old woman presents with dysuria and vaginal discharge. A swab was taken for culture. Culture results showed the presence of Neisseria gonorrhoeae infection. Treatment of azithromycin and doxycycline was started.
Which of the following statements is considered correct regarding Neisseria gonorrhoeae?Your Answer:
Correct Answer: Throat swabs can be used for diagnosis
Explanation:Neisseria gonorrhoeae is a Gram-negative diplococcus that causes gonorrhoea. Gonorrhoea is an acute pyogenic infection of nonciliated columnar and transitional epithelium; infection can be established at any site where these cells are found. Gonococcal infections are primarily acquired by sexual contact and occur primarily in the urethra, endocervix, anal canal, pharynx, and conjunctiva.
In men, acute urethritis, usually resulting in purulent discharge and dysuria (painful urination), is the most common manifestation. The endocervix is the most common site of infection in women. Symptoms of infection, when present, include dysuria, cervical discharge, and lower abdominal pain. Some cases in women may be asymptomatic leading to complications such as pelvic inflammatory disease. Blood-borne dissemination occurs in less than 1% of all infections, resulting in purulent arthritis and rarely septicaemia. Fever and a rash on the extremities can also be present. Other conditions associated with N. gonorrhoeae include anorectal and oropharyngeal infections. Infections in these sites are more common in men who have sex with men but can also occur in women.
Pharyngitis is the chief complaint in symptomatic oropharyngeal infections, whereas discharge, rectal pain, or bloody stools may be seen in rectal gonorrhoea. Approximately 30% to 60% of women with genital gonorrhoea have concurrent rectal infection. Newborns can acquire ophthalmia neonatorum, a gonococcal eye infection, during vaginal delivery through an infected birth canal.
Specimens collected for the recovery of N. gonorrhoeae may come from genital sources or from other sites, such as the rectum, pharynx, and joint
fluid. According to the 2010 STD Treatment guidelines, cephalosporins (e.g., ceftriaxone, cefixime) are currently recommended treatments. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 31
Incorrect
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A 30-year-old man presents with diarrhoea, fever, vomiting, and abdominal cramps. A stool culture was ordered and showed growth of Salmonella spp.
Among the following serotypes of Salmonella spp., which is considered to be the most common cause of salmonella gastroenteritis?Your Answer:
Correct Answer: Serotype D
Explanation:A common cause of gastroenteritis, Salmonella enteritidis, and Salmonella typhi, which causes enteric fever, are both group D. Therefore, serotype D Salmonella species are most commonly associated with gastroenteritis.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 32
Incorrect
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Which of the following statements regarding hookworm is FALSE:
Your Answer:
Correct 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 33
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:
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 34
Incorrect
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Regarding shingles, which of the following statements is CORRECT:
Your Answer:
Correct Answer: You can catch chickenpox from a patient with shingles.
Explanation:After primary infection, VZV remains latent in sensory ganglia and in about 20% of patients will reactivate resulting in shingles, a painful vesicular rash in the related dermatome. Shingles usually affects older people and the immunocompromised. Shingles lesions are infectious to non-immune individuals who are at risk of developing chickenpox. Shingles can not be contracted directly from chickenpox, or from other cases of shingles. Shingles is treated with systemic antiviral treatment to reduce the severity and duration of pain, reduce complications, and reduce viral shedding.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 35
Incorrect
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Which of the following microbes binds strongly to CD4 antigen:
Your Answer:
Correct Answer: HIV
Explanation:HIV mainly infects CD4+ T helper cells. Viral replication results in progressive T-cell depletion and impaired cell-mediated immunity with subsequent secondary opportunistic infections and increased risk of malignancy. B-cell function is also reduced as a result of lack of T-cell stimulation.
HIV is not a notifiable disease. -
This question is part of the following fields:
- Microbiology
- Principles
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Question 36
Incorrect
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A 21-year-old student presents with fever, headache, malaise, fatigue, and muscle aches after returning from a trip to India. A diagnosis of malaria was suspected.
Which of the following statements is considered correct regarding malaria?Your Answer:
Correct Answer: Haemoglobinuria and renal failure following treatment is suggestive of Plasmodium falciparum
Explanation:Malaria results from infection with single-celled parasites belonging to the Plasmodium genus. Five species of Plasmodium are known to cause disease in humans: P. falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi.
Chloroquine remains the mainstay of treatment for uncomplicated vivax malaria.
The female Anopheles mosquito serves as the biologic vector and definitive host.
A complication of infection with P. falciparum is blackwater fever, a condition characterized by haemoglobinuria.
Plasmodium ovale has the longest incubation period, which can be up to 40 days. Plasmodium falciparum has a shorter incubation period of 7-14 days.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 37
Incorrect
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A patient with a recent diagnosis of Hepatitis B would like to find out further information regarding his diagnosis and prognosis.
Which among the following statements is considered true regarding Hepatitis B?Your Answer:
Correct Answer: 60-65% of patients that contract hepatitis B show subclinical disease
Explanation:As the immune response is activated, the virus is slowly cleared from the system, and most patients become non-infectious. In adults, about 50% of infections are asymptomatic; 20% to 30% of patients exhibit clinical jaundice but have a benign resolution of the infection. Therefore, about 80% of infections do not cause serious sequelae. The risk for chronic infection is inversely proportional to age at time of infection, with approximately 90% of infants and only 3% of adults developing a chronic infection.
Individuals with a chronic infection have a higher risk of liver disease, such as cirrhosis or hepatic carcinoma. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 38
Incorrect
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You are treating a patient with a Clostridium difficile infection. His condition was found to be antibiotic-associated. Which of the following pieces of advice on preventing the spread of this disease should you give this patient?
Your Answer:
Correct Answer: Washing hands with soap and water
Explanation:Clostridium difficile (C. diff) can cause colitis, or inflammation of the colon.
To prevent its spread, one should practice good hand hygiene, regularly clean areas of the home that may become contaminated with C. difficile, practice good hand hygiene, and clean surfaces, spills, and accidents.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 39
Incorrect
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A 24-year-old patient is suspected to have a possible acute hepatitis B infection and is currently under investigation.
Which of the following markers is considered the earliest indicator of acute infection in acute Hepatitis B?Your Answer:
Correct Answer: Hepatitis B surface Ag
Explanation:HBsAg is the serological hallmark of HBV infection. After an acute exposure to HBV, HBsAg appears in serum within 1 to 10 weeks. Persistence of this marker for more than 6 months implies chronic HBV infection.
Anti-HBs is known as a neutralizing antibody, and confers long-term immunity. In patients with acquired immunity through vaccination, anti-HBs is the only serological marker detected in serum.
HBcAg is an intracellular presence in infected hepatocyte, thus it is not identified in the serum. During acute infection, anti-HBc IgM and IgG emerges 1–2 weeks after the presence of HBsAg along with raised serum aminotransferase and symptoms. After 6 months of acute infection, anti-HBc IgM wears off. Anti-HBc IgG continues to detect in both patients with resolved HBV infection and chronic hepatitis B.
Hepatitis D virus, also known as the delta hepatitis virus, is a defective ssRNA virus that requires HBV for replication. The infection can occur in one of two clinical forms, co-infection or superinfection. In a co-infection, the patient is simultaneously infected with HBV and HDV. In a superinfection, an HDV infection develops in a patient with a chronic HBV infection.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 40
Incorrect
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Question 41
Incorrect
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A 18-year-old man returns from a trip to Ibiza with a severely painful left eye. He has copious mucopurulent discharge, is febrile and has left-sided tender preauricular lymphadenopathy. He attends the local eye casualty and is diagnosed with hyperacute conjunctivitis.
What is the SINGLE most likely causatiave organism?Your Answer:
Correct Answer: Neisseria gonorrhoeae
Explanation:Hyperacute bacterial conjunctivitis is a severe, sight-threatening ocular infection that warrants immediate ophthalmic work-up and management. The infection has an abrupt onset and is characterized by a copious yellow-green purulent discharge that reaccumulates after being wiped away. Typically caused by infection with Neisseria gonorrhoeae.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 42
Incorrect
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Campylobacter jejuni is primarily spread via which of the following routes:
Your Answer:
Correct 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 43
Incorrect
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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:
Correct 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 44
Incorrect
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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:
Correct 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 45
Incorrect
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A 65-year-old man presents with cough and shortness of breath. His sputum is rusty in colour and is suffering from a fever. Upon examination, it was noted that he has crackles in the right upper lobe. A chest X-ray showed the presence of a right upper lobe cavitation.
Among the following microorganisms, which is considered to be mostly associated with a cavitating upper lobe pneumonia?Your Answer:
Correct Answer: Klebsiella pneumoniae
Explanation:Klebsiella pneumoniae is among the most common Gram-negative bacteria encountered by physicians worldwide and accounts for 0.5-5.0% of all cases of pneumonia. This organism can cause extensive pulmonary necrosis and frequent cavitation.
It is one of the causes that could be suspected when there is cavitatory pneumonia with or without a bulging fissure sign. Often, there can be extensive lobar opacification with air bronchograms.
A helpful feature which may help to distinguish from pneumococcal pneumonia is that Klebsiella pneumoniae develops cavitation in 30-50% of cases (in comparison, cavitation is rare in pneumococcal pneumonia). This occurs early and progresses quickly.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 46
Incorrect
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A 50-year-old man from Russia presents with a history of cough with blood-stained sputum, fever, night sweats, and weight loss. Suspecting tuberculosis, you begin investigations.
All the following statements regarding tuberculosis (TB) are true EXCEPT?Your Answer:
Correct Answer: Corticosteroid use is not a risk factor for developing TB
Explanation:Immunosuppressants like corticosteroids may be an important risk factor for developing tuberculosis.
All of the other statements are true.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 47
Incorrect
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A 32-year-old woman presents with abdominal pain and bloody diarrhoea that has been going on for 3 days.
Among the following microorganisms, which is considered to be a cause of infectious bloody diarrhoea?Your Answer:
Correct Answer: Entamoeba histolytica
Explanation:The following are organisms that are capable of producing acute, bloody diarrhoea:
– Campylobacter jejuni
– Escherichia coli O157:H7
– Salmonella species
– Shigella species
– Yersinia species
– Entamoeba histolyticaOther E. coli strains, Giardia, Vibrio, and other parasites are associated with watery, but not bloody, diarrhoea.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 48
Incorrect
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A patient with history of weight loss and diarrhoea was found out to have Giardia lamblia in her stool since returning from a holiday to Nepal.
Which of the following statements is considered true regarding the life cycle of Giardia lamblia?Your Answer:
Correct Answer: Trophozoites attach to the intestinal wall via a specialised sucking disc
Explanation:Cysts are resistant forms and are responsible for transmission of giardiasis. Both cysts and trophozoites can be found in the faeces (diagnostic stages). The cysts are hardy and can survive several months in cold water. Infection occurs by the ingestion of cysts in contaminated water, food, or by the faecal-oral route (hands or fomites).
In the small intestine, excystation releases trophozoites (each cyst produces two trophozoites).
Trophozoites multiply by longitudinal binary fission, remaining in the lumen of the proximal small bowel where they can be free or attached to the mucosa by a ventral sucking disk.
Encystation occurs as the parasites transit toward the colon. The cyst is the stage found most commonly in non diarrheal faeces.
Because the cysts are infectious when passed in the stool or shortly afterward, person-to-person transmission is possible. While animals are infected with Giardia, their importance as a reservoir is unclear. -
This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 49
Incorrect
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A patient with profuse watery diarrhoea was found to have C. difficile cytotoxin. Which of the following complications is NOT a typical complication of pseudomembranous colitis:
Your Answer:
Correct Answer: Volvulus
Explanation:Dehydration, electrolyte imbalance, acute kidney injury secondary to diarrhoea, toxic megacolon, bowel perforation, and sepsis secondary to intestinal infection are all possible complications of pseudomembranous colitis.
When the intestine twists around itself and the mesentery that supports it, an obstruction is created. This condition is known as a volvulus. Volvulus is caused by malrotation and other anatomical factors, as well as postoperative abdominal adhesions, and not by Clostridium difficile infection.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 50
Incorrect
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Regarding Clostridium tetani, which of the following statements is CORRECT:
Your Answer:
Correct 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 stiffness
Dysphagia
Calf and pectoral muscle rigidity
Fever
Hypertension
Tachycardia
Spasms 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. -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 51
Incorrect
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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:
Correct 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 52
Incorrect
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A 7-year-old boy is brought to the emergency room with complaints of a red and painful left eye. Upon physical examination, it was noted that there is the presence of conjunctival erythema. A mucopurulent discharge and crusting of the lid was also evident. A diagnosis of bacterial conjunctivitis was made.
According to the latest NICE guidelines, which of the following should NOT be a part of the management of this patient?Your Answer:
Correct Answer: Topical antibiotics should be prescribed routinely
Explanation:The following are the NICE guidelines on the management of bacterial conjunctivitis:
– Infective conjunctivitis is a self-limiting illness that usually settles without treatment within 1-2 weeks. If symptoms persist for longer than two weeks they should return for review.
– Seek medical attention urgently if marked eye pain or photophobia, loss of visual acuity, or marked redness of the eye develop.
– Remove contact lenses, if worn, until all symptoms and signs of infection have completely resolved and any treatment has been completed for 24 hours.
– Lubricant eye drops may reduce eye discomfort; these are available over the counter, as well as on prescription.
– Clean away infected secretions from eyelids and lashes with cotton wool soaked in water.
– Wash hands regularly, particularly after touching the eyes.
– Avoid sharing pillows and towels.
– It is not necessary to exclude a child from school or childcare if they have infective conjunctivitis, as mild infectious illnesses should not interrupt school attendance. An exception would be if there is an outbreak of infective conjunctivitis, when advice should be sought from the Health Protection Agency by the school.
– Adults who work in close contact with others, or with vulnerable patients, should avoid such contact until the discharge has settled. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 53
Incorrect
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A patient has a diagnosis of acute osteomyelitis. They have no joint prosthesis on indwelling metal work and no known drug allergies. He has had a recent skin swab that has cultured MRSA and MRSA infection is suspected.
Which of the following antibacterial agents would be most appropriate to prescribe in this case? Select ONE answer only.Your Answer:
Correct Answer: Vancomycin
Explanation:In the majority of patients the commonest causative organism for osteomyelitis isStaphylococcus aureus.Salmonella spp. are the commonest cause in patients with sickle cell disease.
Other bacteria that can cause osteomyelitis include:
Enterobacter spp.
Group A and B streptococcus
Haemophilus influenzae
The current recommendations by NICE and the BNF on the treatment of osteomyelitis are:
Flucloxacillin first-line
Consider adding fusidic acid or rifampicin for initial 2 weeks
If penicillin allergic use clindamycin
If MRSA is suspected use vancomycin
Suggested duration of treatment is 6 weeks for acute infection -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 54
Incorrect
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What is the primary route of transmission of Norovirus?
Your Answer:
Correct Answer: Oral-faecal route
Explanation:Norovirus is spread primarily by faecal-oral contact, but it can also be spread through contact with an infected person, ingestion of contaminated food or water, or contact with contaminated surfaces or items.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 55
Incorrect
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All of the following single clinical risk groups is considered eligible to receive the seasonal influenza vaccination, except:
Your Answer:
Correct Answer: Patients with hypertension
Explanation:The following is the list of all the health and age factors that are known to increase a person’s risk of getting serious complications from flu:
– Adults 65 years and older
– Children younger than 2 years old
– Asthma
– Neurological and neurodevelopmental conditions
– Blood disorders (such as sickle cell disease)
– Chronic lung disease (such as chronic obstructive pulmonary disease [COPD] and cystic fibrosis)
– Endocrine disorders (such as diabetes mellitus)
– Heart disease (such as congenital heart disease, congestive heart failure and coronary artery disease)
– Kidney diseases
– Liver disorders
– Metabolic disorders (such as inherited metabolic disorders and mitochondrial disorders)
– People who are obese with a body mass index [BMI] of 40 or higher
– People younger than 19 years old on long-term aspirin- or salicylate-containing medications.
– People with a weakened immune system due to disease (such as people with HIV or AIDS, or some cancers such as leukaemia) or medications (such as those receiving chemotherapy or radiation treatment for cancer, or persons with chronic conditions requiring chronic corticosteroids or other drugs that suppress the immune system)
– People who have had a stroke
– Pregnant people and people up to 2 weeks after the end of pregnancy
– People who live in nursing homes and other long-term care facilities -
This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 56
Incorrect
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All of the following statements regarding Helicobacter pylori is considered true, except:
Your Answer:
Correct 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 57
Incorrect
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A migrant from Eastern Europe needs to have screening performed for tuberculosis (TB) because he is a high-risk patient.
Which statement concerning TB screening in the UK is true?
Your Answer:
Correct Answer: Vaccination with the BCG can result in a false positive test
Explanation:Vaccination with the BCG can result in a false positive test.
The Mantoux test replaced the Heaf test as the TB screening test in the UK in 2005.
The ‘Sterneedle’ gun is used to inject 100,000 units/ml of tuberculin purified protein derivative into the skin for the Heaf testThe Mantoux test involves the injection of 5 Tuberculin units (0.1mL) intradermally and the result read 2-3 days later.
The interferon gamma release assay (IGRA) should NOT be used for neonates
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 58
Incorrect
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A 63 year old lady presents to ED with a persistent cough and red currant jelly sputum. She has a history of chronic alcohol abuse and has an X-ray which demonstrates a cavitating pneumonia. The most likely causative pathogen is:
Your Answer:
Correct Answer: Klebsiella pneumoniae
Explanation:One of the results of Klebsiella pneumoniae is pneumonia that is usually a very severe infection. It is characterised by thick, bloody sputum (red currant jelly sputum), and is associated with complications like lung abscess, cavitation, necrosis, empyema and pleural effusions.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 59
Incorrect
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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:
Correct 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 60
Incorrect
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Diagnosis of HIV is predominantly made through which of the following:
Your Answer:
Correct 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 61
Incorrect
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A 6 year old boy is brought into the ED by his mom with a rash that is associated with Koplik's spots and a diagnosis of measles is made. What advice should be given about returning to school?
Your Answer:
Correct Answer: 4 days from the onset of the rash
Explanation:Prevention of spread of measles is extremely important and infected patients should be isolated. The infectious stage is from 3 days before the rash emerges and patients are advised to stay away from school/nursery/work for 4 days from onset of the rash.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 62
Incorrect
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The percentage of patients with hepatitis B that develop chronic infection is about:
Your Answer:
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 63
Incorrect
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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:
Correct 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 64
Incorrect
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A 73-year-old woman arrives at the emergency department 48 hours after being discharged from the hospital after a two-week stay for sepsis treatment. She has fever, productive cough with thick green sputum, and shortness of breath. An X-ray shows left lower lobe pneumonia. Which of the bacteria listed below is more likely to be the causative agent:
Your Answer:
Correct Answer: Pseudomonas aeruginosa
Explanation:Hospital-acquired pneumonia (HAP), or nosocomial pneumonia, is a lower respiratory infection that was not incubating at the time of hospital admission and that presents clinically 2 or more days after hospitalization. Pneumonia that presents sooner should be regarded as community acquired pneumonia. VAP refers to nosocomial pneumonia that develops among patients on ventilators. Ventilator-associated pneumonia (VAP) is defined as pneumonia that presents more than 48 hours after endotracheal intubation.
Common bacteria involved in hospital-acquired pneumonia (HAP) include the following [10] :
Pseudomonas Aeruginosa
Staphylococcus aureus, including methicillin-susceptible S aureus (MSSA) and methicillin-resistant S aureus (MRSA)
Klebsiella pneumoniae
Escherichia coli -
This question is part of the following fields:
- Infections
- Microbiology
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Question 65
Incorrect
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Regarding meningococcal meningitis, which of the following statements is CORRECT:
Your Answer:
Correct Answer: Infection occurs most commonly below the age of 5 years.
Explanation:About half of meningococcal disease occurs in children aged less than five years, and babies are at the highest risk because their immune systems have not yet fully developed. There is a second, smaller increase in risk for older adolescents, mainly for social and behavioural reasons. Infection is most common in winter months. Antibiotics should be given as soon as the diagnosis is suspected (ideally cultures should be performed first but this should not delay treatment), and ceftriaxone/cefuroxime is the first line antibiotic. Only healthcare workers who have been directly exposed to large particle droplets/secretions from the respiratory tract of the index case should receive prophylaxis.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 66
Incorrect
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Regarding Escherichia coli, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: It is a predominant member of the normal flora of the skin.
Explanation:Escherichia coli is a Gram-negative bacilli that is an important member of the intestinal flora. It is the most common cause of UTI in adults (about 70 – 95% of cases), followed by Staphylococcus saprophyticus (about 5 – 10% of cases), and an important cause of neonatal meningitis. E. coli O157 strain is implicated in the development of dysentery associated with haemolytic uraemic syndrome characterised by haemolytic anaemia, thrombocytopenia and acute renal failure.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 67
Incorrect
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Herpes simplex encephalitis has a predilection for which of the following sites:
Your Answer:
Correct Answer: Temporal lobe
Explanation:Herpes simplex virus is the most common cause of infective encephalitis and has a predilection for the temporal lobes. Herpes simplex is transmitted through direct contact. It invades skin locally producing skin vesicles by its cytolytic activity.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 68
Incorrect
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A patient is diagnosed with a Klebsiella infection.
Which SINGLE statement regarding Klebsiella infections is true?Your Answer:
Correct Answer: Klebsiella spp are an important cause of ventilator-associated pneumonia
Explanation:Klebsiellais a genus of non-motile,Gram-negative, rod-shaped bacteriawith a prominent polysaccharide-based capsule. They are routinely found in the nose, mouth and gastrointestinal tract as normal flora, however, they can also behave as opportunistic pathogens.
Infections with Klebsiella spp. areusually nosocomial. They are an important cause of ventilator-associated pneumonia (VAP), urinary tract infection, wound infection and bacteraemia. Outbreaks of infections with Klebsiellaspp. in high-dependency units have been described and are associated with septicaemia and high mortality rates. Length of hospital stay and performance of invasive procedures are risk factors forKlebsiellainfections.
Primary pneumonia withKlebsiella pneumoniaeis a rare,severe, community-acquired infection associated with a poor outcome.
Klebsiella rhinoscleromatis causes a progressive granulomatous infection of the nasal passages and surrounding mucous membranes. This infection is mainly seen in the tropics.
Klebsiella ozanae is a recognised cause of chronic bronchiectasis.
Klebsiella organisms are resistant to multiple antibiotics including penicillins. This is thought to be a plasmid-mediated property. Agents with high intrinsic activity againstKlebsiellapneumoniaeshould be selected for severely ill patients. Examples of such agents include third-generation cephalosporins (e.g cefotaxime), carbapenems (e.g. imipenem), aminoglycosides (e.g. gentamicin), and quinolones (e.g. ciprofloxacin). These agents may be used as monotherapy or combination therapy. Aztreonam may be used in patients who are allergic to beta-lactam antibiotics.
Species with ESBLs (Extended spectrum beta-lactamase) are resistant to penicillins and also cephalosporins such as cefotaxime and ceftriaxone
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 69
Incorrect
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A 30-year-old man present to the ED with abdominal pain, nausea and vomiting. It has been present for the past two days.
Which of the following statements regarding diarrhoea and vomiting is true?
Your Answer:
Correct Answer: E.Coli can cause diarrhoea and renal failure
Explanation:Escherichia coli strain 0157 causes enterohaemorrhagic diarrhoea and can lead to renal failure, haemolytic anaemia and thrombocytopenia.
Norwalk virus is an RNA virus.
Although transmission of rotavirus is primarily through the faeco-oral route, airborne spread has been seen in some cases.
Cryptosporidium are protozoa with acid fast walls and are resistant to both chlorine treatment and conventional filtering methods.
There is no therapy effective in treating cryptosporidium diarrhoea as the protozoa is not susceptible to antibiotics.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 70
Incorrect
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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:
Correct 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 71
Incorrect
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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:
Correct 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 72
Incorrect
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Streptococcus pneumoniae is commonly implicated in all of the following infectious diseases EXCEPT for:
Your Answer:
Correct Answer: Impetigo
Explanation:Impetigo is a highly contagious infection of the superficial epidermis that most commonly affects young children but can occur in any age group. In children it is the most common bacterial skin infection and it is the third most common skin disease overall, behind dermatitis and viral warts.
The commonest causative organism is Staphylococcus aureus. Streptococcus pyogenesis the second commonest and causes fewer cases, either alone or in combination withS. aureus.The streptococcal form tends to be commoner in warmer, more humid climates. (Hirschmann JV. Impetigo: etiology and therapy. Curr Clin Top Infect Dis. 2002;22:42–51.)
Impetigo is most commonly spread by direct person-to-person contact, and can spread rapidly through families and school classes. It can also, less commonly, be spread by indirect contact.
There are two main forms of impetigo:
Non-bullous impetigo – lesions usually start as tiny pustules or vesicles that evolve rapidly into honey-crusted plaques that tend to be under 2 cm in diameter. These can be itchy but are rarely painful.
Bullous impetigo – lesions have a thin roof and tend to rupture spontaneously. This type is more likely to be painful and may be associated with systemic upset. -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 73
Incorrect
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A 15-year-old boy was brought to the emergency room with complaints of a headache, stiffness of the neck, and photophobia. Upon observation, the following were noted: HR 124, BP 86/43, RR 30, SaO 95%, temperature 39.5 deg C. A recently developed non-blanching rash on his legs was also observed.
What is most likely the causative agent of the case presented above?Your Answer:
Correct Answer: Neisseria meningitidis group B
Explanation:The meningococcus is solely a human pathogen, and up to 50% of the population may carry meningococci in the nasopharynx. Factors that lead to invasion and production of disease include complex inter-relationships of genetic predisposition, host status, environmental conditions, and virulence of the organism.
Meningococcal disease is the most common infectious cause of death in childhood in developed countries. It presents as septicaemia, meningitis, or a combination. Septicaemia is the more dangerous presentation, especially with septic shock; meningitis is more likely to lead to neurodevelopmental sequelae. Classic features of septicaemia are a non-blanching rash in a feverish, ill child.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 74
Incorrect
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Regarding gas gangrene, which of the following statements is CORRECT:
Your Answer:
Correct 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 75
Incorrect
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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:
Correct 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 76
Incorrect
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Bordetella pertussis causes which of the following infectious diseases:
Your Answer:
Correct 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 77
Incorrect
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A 29-year-old woman presents with night sweats, fever, and haemoptysis. A diagnosis of tuberculosis was suspected.
Which of the following statements regarding the diagnosis of tuberculosis is considered correct?Your Answer:
Correct Answer: Mycobacteria tuberculosis can be typed using a RFLP method
Explanation:Although a variety of clinical specimens may be submitted to the
laboratory to recover MTB and NTM, respiratory secretions such
as sputum and bronchial aspirates are the most common. An
early-morning specimen should be collected on three consecutive
days, although recent studies have suggested that the addition of
a third specimen does not significantly increase the sensitivity
of detecting Mycobacteria.Mycobacterium tuberculosis appear red on acid-fast staining because they take up the primary stain, which is carbolfuchsin, and is not decolorized by the acid alcohol anymore.
Culture on Lowenstein-Jensen medium should be read within 5 to 7 days after inoculation and once a week thereafter for up to 8 weeks.
Nucleic acid amplification assays designed to detect M. tuberculosis complex
bacilli directly from patient specimens can be performed in as little as 6 to 8 hours on processed specimens. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 78
Incorrect
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Question 79
Incorrect
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Regarding hepatitis C, which of the following statements is INCORRECT:
Your Answer:
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 80
Incorrect
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A 32-year old male patient has been diagnosed with meningococcal meningitis and was given appropriate treatments. Because he is a family man, he fears that he might transmit the infection to the rest of his family members.
The causative agent of meningococcal meningitis is spread via what mode of transmission?Your Answer:
Correct Answer: Respiratory droplet route
Explanation:N. meningitidis, the causative agent of meningococcal meningitis, is considered both a commensal and a pathogen. It can be found in the surfaces of mucous membranes such as the nasopharynx and oropharynx. With this, it can be transmitted from a carrier to a new host via respiratory droplet secretions.
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This question is part of the following fields:
- Microbiology
- Pathogens
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