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Question 1
Correct
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Regarding hepatitis C, which of the following statements is INCORRECT:
Your 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 2
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: Clarithromycin
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 daysLate-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.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 3
Incorrect
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You review a 37-year-old man with a history of intravenous drug abuse who admits to sharing needles in the past. He has a flu-like illness and a rash. Concerned he may be experiencing an HIV seroconversion illness, you order a test.Which of these tests is most reliably used to diagnose HIV at this stage?
Your Answer: CD4 count
Correct Answer: p24 antigen test
Explanation:Serum concentrations of the p24 antigen are usually high in the first few weeks after human immunodeficiency virus (HIV) infection and testing for p24 antigen is therefore a useful way of diagnosing very early infection. P24 is the viral protein that makes up most of the core of the HIV.ELISA and other antibody tests, though a very sensitive way of detecting the presence of HIV, cannot be used in the early stages of the disease. This is because of the window period of 6-12 weeks before antibodies are produced. These tests will be negative during a seroconversion illness.The ‘rapid HIV test’ is an HIV antibody test. It will also be negative during the ‘window period’ since it takes time for antibodies to be produced. It is called the ‘rapid test’ as it can detect antibodies in blood or saliva much quicker than the other antibody tests and results are often back within 20 minutes.CD4 and CD8 counts are usually normal in the early stages of the HIV infection and cannot be used in this case.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 4
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 5
Incorrect
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Regarding Clostridium perfringens, which of the following statements is CORRECT:
Your Answer: It has endotoxin-mediated effects in tissue causing severe tissue damage.
Correct Answer: It can cause exotoxin-mediated food poisoning.
Explanation:Clostridium perfringens is an obligate anaerobe and has exotoxin mediated effects. It is the most common cause of gas gangrene. C. perfringens is also implicated in food poisoning, cellulitis, enteritis necrotican (life-threatening infection involving ischaemic necrosis of the jejunum), and rarely, CNS infections such as meningitis and encephalitis.
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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 23-year-old student presents to the emergency department with a terrible headache, photophobia, and a fever. On her lower limbs, you see a non-blanching purpuric rash. In the department, a lumbar puncture is conducted. What do you think you'll notice on Gram stain:
Your Answer: Gram negative diplococci
Explanation:Bacterial meningitis and septicaemia are most commonly caused by meningococcal bacteria. The Gram-negative diplococci Neisseria Meningitidis causes meningitis. Gram stain and culture of CSF identify the etiologic organism, N meningitidis. In bacterial meningitis, Gram stain is positive in 70-90% of untreated cases, and culture results are positive in as many as 80% of cases.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 7
Incorrect
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Diagnosis of HIV is predominantly made through which of the following:
Your Answer: Viral PCR
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 8
Correct
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You are planning on starting antibiotic therapy for a patient with a diagnosis of gonorrhoea.Which of these is the MOST appropriate antibiotic combination?
Your Answer: Ceftriaxone and azithromycin
Explanation:Currently, ceftriaxone in combination with azithromycin or doxycycline is the combination of antibiotics used in the treatment of gonorrhoea.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 9
Correct
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Bordetella pertussis causes which of the following infectious diseases:
Your Answer: Whooping cough
Explanation:Bordetella pertussis causes whooping cough. Acute bronchiolitis is typically caused by respiratory syncytial virus. Parainfluenza virus is the most common cause of croup. Acute epiglottitis is usually caused by an infection with Haemophilus influenzae type b (Hib) bacteria. The common cold may be caused by a number of viruses including rhinovirus and coronavirus.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 10
Incorrect
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Regarding Clostridium tetani, which of the following statements is CORRECT:
Your Answer: It produces exotoxins A and B and binary toxin.
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 stiffnessDysphagiaCalf and pectoral muscle rigidityFeverHypertensionTachycardiaSpasms can occur frequently and last for several minutes, they can continue to occur for up to 4 weeks. Current mortality rates are between 10 and 15%.Tetanic spasms are caused by the exotoxin tetanospasmin. The effects of tetanolysin are not fully understood but it is not believed to have clinical significance.Localised tetanus is a rare form of the disease, occurring in around 1% of affected individuals. Patients have persistent contraction of muscles in the same anatomic area as the injury. It may precede generalised tetanus.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 11
Correct
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An elderly man with chronic heart and lung disease develops Legionnaires' Disease. By what route was the infection most likely to have been acquired:
Your Answer: Inhalation of aerosolised contaminated water
Explanation:Legionella pneumophilais a Gram negative bacterium that is found in natural water supplies and in the soil, transmitted predominantly via inhalation of aerosols generated from contaminated water (direct person-to-person spread of infected patients does not occur). It is the cause of Legionnaires’ disease. Outbreaks of Legionnaires’ disease have been linked to poorly maintained air conditioning systems, whirlpool spas and hot tubs.The clinical features of the pneumonic form of Legionnaires’ disease include:Mild flu-like prodrome for 1-3 daysCough (usually non-productive and occurs in approximately 90%)Pleuritic chest painHaemoptysisHeadacheNausea, vomiting and diarrhoeaAnorexiaLegionella pneumophilainfections can be successfully treated with macrolide antibiotics, such as erythromycin, or quinolones, such as ciprofloxacin. Tetracyclines, such as doxycycline, can also be used.The syndrome of inappropriate antidiuretic hormone secretion (SIADH) can occur with Legionnaires’ disease and will result in hyponatraemia as is seen in this case.Legionella pneumophilainfections are resistant to amoxicillin but can be successfully treated with macrolide antibiotics, such as erythromycin, or quinolones, such as ciprofloxacin. Tetracyclines, such as doxycycline, can also be used. The majority of cases of Legionnaires’ disease are caused by Legionella pneumophila, however many other species of Legionella have been identified.Legionella longbeachae is another less commonly encountered species that has also been implicated in outbreaks. It is predominantly found in soil and potting compost, and has caused outbreaks of Pontiac fever, the non-respiratory and less severe variant of Legionnaires’ disease.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 12
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: Respiratory syncytial virus
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 13
Correct
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An 11-year-old girl presents with a 5-day history of persistent fever despite regular paracetamol, throbbing left ear pain, ear discharge and deafness. Her parents have observed that she is not her usual self, not eating well, and has been lethargic. On examination there is a tender swelling in the post auricular region on the left hand side.What is the most likely causative organism?
Your Answer: Streptococcus pneumonia
Explanation:Acute mastoiditis is a complication (rare) of acute otitis media (AOM) and the commonest causative organism is Streptococcus pneumoniae.Generally, acute mastoiditis presents with:PyrexiaRecent history of AOMMastoid swelling and erythemaOtalgiaOtorrhoea and perforation of tympanic membranePost-auricular painProtrusion of the ears
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 14
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 15
Correct
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In the emergency room, a patient was diagnosed with acute bacterial tonsillitis. Which of the following postinfectious complications is most commonly linked to Streptococcus pyogenes:
Your Answer: Glomerulonephritis
Explanation:Poststreptococcal glomerulonephritis (PSGN) is caused by prior infection with specific nephritogenic strains of group A beta-haemolytic streptococcus. The clinical presentation of PSGN varies from asymptomatic, microscopic haematuria to the full-blown acute nephritic syndrome, characterized by red to brown urine, proteinuria (which can reach the nephrotic range), oedema, hypertension, and acute kidney injury.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 16
Incorrect
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Cryptococcus neoformans is primarily transmitted by which of the following routes:
Your Answer: Respiratory droplet spread
Correct 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 17
Incorrect
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One of the following pathogens is a conditional pathogen:
Your Answer: Mycobacterium tuberculosis
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 18
Incorrect
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Regarding Clostridium tetani, which of the following statements is CORRECT:
Your Answer: Clostridium tetani is not found in the human intestinal flora.
Correct Answer: Germination and outgrowth of clostridial spores depends on anaerobic conditions.
Explanation:Clostridium tetani is found in normal human intestinal flora, although infection is predominantly exogenous. Tetanospasmin, an exotoxin produced by C. tetani is responsible for the neurotoxic effects of tetanus, largely by preventing the release of the inhibitory neurotransmitter GABA, resulting in prolonged excitation. Clostridium tetani is an obligate anaerobe, with an incubation period of about 3 – 21 days (average 10 days).
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 19
Incorrect
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Regarding Escherichia coli, which of the following statements is INCORRECT:
Your Answer: E.coli O157 strain is implicated in the development of haemolytic uraemic syndrome.
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 20
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 21
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 22
Incorrect
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The tetanus vaccination contains inactivated tetanus toxoid, which induces the body to produce protective antibodies. How do these antibodies protect the body from tetanus?
Your Answer:
Correct Answer: Neutralise the protein exotoxin of C. tetani
Explanation:C. Tetanospasmin, an exotoxin produced by tetani, is responsible for the neurotoxic consequences of tetanus. The tetanus vaccination contains inactivated tetanus toxoid, which induces the body to produce protective antibodies that neutralize the tetanus toxin. It induces active immunization against Clostridium tetani exotoxin via toxoid-induced Ab generation.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 23
Incorrect
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Which of these statements about the monospot test is true?
Your Answer:
Correct Answer: It can be positive in rubella
Explanation:Infectious mononucleosis can be diagnosed using specific EBV antibodies and a variety of unrelated non-EBV heterophile antibodies.Heterophile antibodies:About 70-90% of patients with EBV infectious mononucleosis produce antibodies against an antigen produced in one species that react against antigens from other species called heterophile antibodies. False positives can be seen with rubella, hepatitis, SLE, malaria, toxoplasmosis, lymphoma and leukaemia. 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.Paul-Bunnell test uses sheep red blood cells. The blood agglutinates in the presence of heterophile antibodies.EBV-specific antibodies:Patients can remain heterophile-negative after six weeks and are then considered to be heterophile-negative and should be tested for EBV-specific antibodies. EBV-specific antibodies test are helpful if a false positive heterophile antibody test is suspected.The indirect Coombs test is used to detect in-vitro antibody-antigen reactions. It is typically used in antenatal antibody screening and in preparation for blood transfusion.Heterophile antibody tests are generally not positive in the incubation period of infectious mononucleosis (4-6 weeks) before the onset of symptoms.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 24
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.
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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 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:
Correct 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, respiratorytherapy equipment, and industrial process waters.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 26
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 27
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 28
Incorrect
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Which patients are particularly susceptible to infection with herpes simplex, those with:
Your Answer:
Correct Answer: T-cell deficiency
Explanation:Cell-mediated immunity, especially the action of cytotoxic T-cells, is essential in the control of herpesvirus infections and patients with T-cell deficiency are at particular risk of reactivation and severe infection. T-cell deficiency may follow HIV infection, chemotherapy, corticosteroid therapy or organ transplantation.
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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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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 30
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.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 31
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 coccusBacillus cereus = Gram-positive bacillusCampylobacter jejuni = Gram-negative bacillusEscherichia 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.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 32
Incorrect
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Which of the following antibiotics is the first line of treatment for a patient who has been diagnosed with chlamydia infection?
Your Answer:
Correct Answer: Azithromycin
Explanation:The Centres for Disease Control and Prevention (CDC) recommends azithromycin, a single 1 g dose, and doxycycline, 100 mg bd for 7 days, as first-line medications for chlamydial infection treatment. Second-line medications (such as erythromycin, penicillins, and sulfamethoxazole) are less effective and have more side effects
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 33
Incorrect
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One of your patients has been infected by an obligate pathogen and presents with features of this condition.Which of these is an example of an obligate pathogen?
Your Answer:
Correct Answer: Trepenoma pallidum
Explanation:Treponema pallidum is an obligate pathogen. Obligate pathogens are almost always associated with disease and usually cannot survive outside of the body for long periods of time. Examples include and HIV.Staphylococcus aureus and Bacteroides fragilis are conditional pathogens. These are pathogens that usually cause disease only if certain conditions are met.Pneumocystis jiroveci and Pseudomonas aeruginosa, are opportunistic pathogens. These are pathogens that can only cause disease in an immunocompromised host or under unusual circumstances.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 34
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.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 35
Incorrect
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A 12-year-old boy presents to you with a history of fever. A rash began as small red dots on the face, scalp, torso, upper arms and legs shortly afterwards and has now progressed to small blisters and pustules. You make a diagnosis of chickenpox.The following complications of chickenpox is the LEAST likely.
Your Answer:
Correct Answer: Bronchospasm
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:OrchitisHepatitisPneumoniaEncephalitisInfected spotsOtitis mediaMyocarditisGlomerulonephritisAppendicitisPancreatitis
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 36
Incorrect
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Clostridium tetani causes which of the following infectious diseases:
Your Answer:
Correct 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.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 37
Incorrect
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Which of the following nerves is responsible for the symptoms of a patient with history of recurrent herpes simplex outbreaks on his face and presents with ophthalmic herpes zoster and a painful vesicle on the tip of his nose?
Your Answer:
Correct Answer: Nasociliary nerve
Explanation:Hutchinson sign relates to involvement of the tip of the nose from facial herpes zoster. It implies involvement of the external nasal branch of the nasociliary nerve which is a branch of the ophthalmic division of the trigeminal nerve. The nasociliary branch of the trigeminal nerve innervates the apex and lateral aspect of the nose, as well as the cornea. Therefore, lesions on the side or tip of the nose should raise suspicion of ocular involvement.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 38
Incorrect
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Among the following microorganisms, which is considered to be transmitted by invasion of intact skin?
Your Answer:
Correct Answer: Leptospira spp.
Explanation:Rodents and domestic animals are the primary reservoirs for the Leptospira spp, although other animals, including cows, horses, mongooses, and frogs, can also harbour the leptospires. Humans may be directly infected from animal urine or indirectly by contact with soil or water that is contaminated with urine from infected animals. Infected humans can shed leptospires in urine for up to 11 months, infected cows for 3.5 months, infected dogs for 4 years, and infected rodents possibly for their entire lifetime.The organisms enter the host through mucous membranes or abraded skin. The incubation period ranges from 5 to 14 days.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 39
Incorrect
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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:
Correct 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 40
Incorrect
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A 17-year-old patient with a headache, fever, and a non-blanching rash is brought to the emergency room. Meningococcal infection is confirmed by a lumbar puncture. Neisseria meningitidis uses one of the following immune evasion mechanisms:
Your Answer:
Correct Answer: Secretes IgA protease
Explanation:Meningococci have 3 important virulence factors, as follows:Polysaccharide capsule – Individuals with immunity against meningococcal infections have bactericidal antibodies against cell wall antigens and capsular polysaccharides; a deficiency of circulating anti meningococcal antibodies is associated with the disease.Lipo-oligosaccharide endotoxin (LOS)Immunoglobulin A1 (IgA1)
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This question is part of the following fields:
- Microbiology
- Principles
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Question 41
Incorrect
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The monospot test for infectious mononucleosis uses which of the following types of red blood cell?
Your Answer:
Correct 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 42
Incorrect
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Question 43
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 44
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.
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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 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 AeruginosaStaphylococcus aureus, including methicillin-susceptible S aureus (MSSA) and methicillin-resistant S aureus (MRSA)Klebsiella pneumoniaeEscherichia coli
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This question is part of the following fields:
- Infections
- Microbiology
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Question 46
Incorrect
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Which of the following statements is considered correct regarding Hepatitis B vaccination?
Your Answer:
Correct Answer: The vaccine should be stored between 2 and 8 degrees Centigrade
Explanation:Hepatitis B vaccine should be stored at 35°-46° F (2°-8° C) and should not be frozen.There is no association between hepatitis B vaccination and Guillain-Barre syndrome. Infection with the bacterium Campylobacter jejuni is one of the most common risk factors for GBS. People can also develop GBS after having the flu or other infections (such as cytomegalovirus and Epstein Barr virus).Hepatitis B vaccine is prepared from initial concentration of surface antigen.To ensure adequate immunity, anti-HBs (HBsAb) titres may be checked 4-8 weeks following the last shot of the hepatitis B vaccine series.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 47
Incorrect
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Question 48
Incorrect
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A 6-year-old female is brought to the Ophthalmology Clinic by her mother with the complaint of itching, redness, and a watery discharge of the right eye. Past medical history revealed an upper respiratory tract infection one week ago. On examination of the right eye, there is mild erythema of the palpebral conjunctiva and visible follicles seen on eversion of the eyelid, lid oedema, and subconjunctival petechial haemorrhages. The discharge is watery and not purulent. You diagnose her with viral conjunctivitis. According to the current NICE guidelines, which ONE of the following management options would NOT be included for this patient?
Your Answer:
Correct Answer: The child should be excluded from school until the infection has resolved
Explanation:The NICE guidelines do NOT recommend isolating a patient with viral conjunctivitis from others or skipping school or work. The disease is contagious, but the spread of the disease can be controlled by maintaining good hygiene practices such as:1. frequent hand washing2. use of separate flannels and towels3. Avoid close contact with othersAntibiotic prescriptions are not part of the NICE guidelines for viral conjunctivitis as they will not affect the course of the disease. Most cases of viral conjunctivitis are self-limiting and resolve within one to two weeks.The NICE guidelines recommend that symptoms may be eased with self-care measures such as:1. Bathing/cleaning the eyelids with cotton wool soaked in sterile saline or boiled and cooled water to remove any discharge2. Cool compresses applied gently around the eye area3. Use of lubricating drops or artificial tears
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 49
Incorrect
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Which of the following microbes produces exotoxin:
Your Answer:
Correct Answer: Clostridium tetani
Explanation:Clostridium tetani (causing tetanus) produces the exotoxin tetanospasmin which causes its neurotoxic effects.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 50
Incorrect
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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:
Correct 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.
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This question is part of the following fields:
- Microbiology
- Pathogens
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SESSION STATS - PERFORMANCE PER SPECIALTY
