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Question 1
Correct
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A 27 year-old male patient was admitted to the hospital due to recurrent fever for the past 2 weeks. The patient claimed that he is an intravenous drug user. Following work up, the patient was diagnosed with infective endocarditis. Which is the most likely organism responsible for this diagnosis?
Your Answer: Staphylococcus aureus
Explanation:Acute bacterial endocarditis is a fulminant illness lasting over days to weeks (<2weeks). It is most likely due to Staphylococcus aureus especially in intravenous drug abusers.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 2
Incorrect
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Which of the following is NOT a Gram-negative rod?
Your Answer: Legionella
Correct Answer: Clostridium tetani
Explanation:Gram-positive rods include Clostridia, Listeria and diphtheroids.
Gram-negative rods include Escherichia coli, Klebsiella, Yersinia, Haemohilus, Pseudomonas, Shigella, Legionella, proteus and Salmonella
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 3
Correct
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A 45-year-old woman was brought to the emergency department due to fever and chills. She has a history of recurrent UTI and complains of dysuria and urinary frequency. Urinary white blood cell count is >200 cell/high power field. If urine culture is performed, what is the most likely organism that will grow?
Your Answer: Escherichia coli
Explanation:The pathogen that most likely causes recurrent urinary tract infection in young women are E. coli, Enterococcus and Staphylococcus saprophyticus.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 4
Correct
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A 15-year-old girl was diagnosed with bacterial meningitis. Gram staining of the spinal fluid shows numerous polymorphonuclear neutrophils and Gram-positive cocci. Which is the empiric drug of choice to be given to the patient until the antibiotic sensitivity report is available?
Your Answer: Ceftriaxone
Explanation:Acute meningitis is a medical emergency. All suspects should receive their first dose of antibiotics immediately and be transferred to hospital as soon as possible. If facilities for blood culture and/or lumbar puncture (LP) are immediately available, they should be performed before administration
of the first dose of antibiotics (see contraindications to LP below). Neither procedure should lead to a significant delay in antibiotic administration.
Administer ceftriaxone 80-100 mg/kg (maximum 2 g, 12 hourly) intravenously. The intramuscular or intraosseous route can be used if there is no vascular access. Penicillin allergy is not a contraindication to ceftriaxone in acute meningitis (C-1). Omit ceftriaxone only if there has been documented ceftriaxone anaphylaxis. Give chloramphenicol 25 mg/kg (maximum 500 mg) intravenously instead, if available. Administer adequate analgesia and transfer the patient immediately to hospital, detailing all administered
medication in the referral letter. -
This question is part of the following fields:
- Microbiology
- Pathology
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Question 5
Correct
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A 5-year-old child presents with fever and otalgia. Greenish pustular discharge was seen in his left ear during physical examination. The patient is diagnosed with otitis externa. Which of the following organisms most likely caused the infection?
Your Answer: Pseudomonas aeruginosa
Explanation:P. aeruginosa is a multidrug resistant pathogen recognised for its ubiquity, its advanced antibiotic resistance mechanisms and its association with serious illnesses – especially hospital-acquired infections such as ventilator-associated pneumonia and various septic syndromes. The species name aeruginosa is a Latin word meaning verdigris (copper rust), referring to the blue-green colour of laboratory cultures of the species. This blue-green pigment is a combination of two metabolites of P. aeruginosa, pyocyanin (blue) and pyoverdine (green), which impart the blue-green characteristic colour of cultures.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 6
Incorrect
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Anthrax is an infection caused by the bacterium Bacillus anthracis. Anthrax spores have been used as a biological warfare weapon. What is the drug of choice in treating anthrax infection?
Your Answer: Tetracycline
Correct Answer: Ciprofloxacin
Explanation:Early antibiotic treatment of anthrax is essential. A delay may significantly lessen the chances for survival of the patient. Treatment for anthrax infection include large doses of intravenous and oral antibiotics, such as fluoroquinolones (ciprofloxacin), doxycycline, erythromycin, vancomycin, or penicillin.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 7
Incorrect
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A 68-year-old man underwent sigmoid resection with diverting colostomy for a ruptured sigmoid diverticulum 10 days ago. He received gentamicin and ampicillin post-op. 2 days after he was discharged from the hospital, he was readmitted because of high grade fever and chills. His blood culture grew Gram-negative bacilli. Which organism is most likely responsible for the patient's infection?
Your Answer: Escherichia coli
Correct Answer: Bacteroides fragilis
Explanation:Bacteroides fragilis is an anaerobic, Gram-negative, rod-shaped bacterium. It is part of the normal flora of the human colon and is generally a commensal, but can cause infection if displaced into the bloodstream or surrounding tissue following surgery, disease, or trauma.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 8
Correct
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Gram positive bacteria differ from gram negative bacteria due to the presence of which of the following structures?
Your Answer: Outer membrane
Explanation:The reason bacteria are either Gram-positive or Gram-negative is due to the structure of their cell envelope (the cell envelope is defined as the cell membrane and cell wall plus an outer membrane, if one is present.) Gram-positive bacteria, for example, retain the crystal violet due to the amount of peptidoglycan in the cell wall. It can be said therefore that the Gram-stain procedure separates bacteria into two broad categories based on structural differences in the cell envelope.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 9
Correct
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A patient is suspected to have Blastomyces dermatidis infection. The patient contracted the disease most likely through which port of entry?
Your Answer: Respiratory tract
Explanation:Blastomycosis disease is a fungal infection acquired through inhalation of the spores. It caused by the organism Blastomyces dermatitidis and manifests as a primary lung infection in about 70% of cases. The onset is relatively slow and symptoms are suggestive of pneumonia.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 10
Correct
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A 25 year-old female medical student presents with fever, lack of appetite, rashes, sore throat and lymphadenopathy. Peripheral smear shows atypical lymphocytes. Which is the most likely organism responsible for this patient's condition?
Your Answer: Epstein–Barr virus
Explanation:Epstein-Barr virus is in the herpes family of viruses and most people will become infected with EBV sometime during their lives. EBV commonly causes infectious mononucleosis, or mono, a contagious viral illness that initially attacks the lymph nodes in the neck and throat. When these tissues become less effective in fighting infection, sore throats, swelling of the nodes and fever may result.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 11
Incorrect
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A 37-year-old woman with a history of rheumatic heart disease presents with 10 days recurrent low fever. Patient underwent laboratory work up and was diagnosed with infective endocarditis. What is the most likely organism that caused the infective endocarditis in this patient?
Your Answer: Streptococcus pneumoniae
Correct Answer: Streptococcus viridans
Explanation:Subacute bacterial endocarditis is often due to streptococci of low virulence, mainly streptococcus viridans. It is a mild to moderate illness which progresses slowly over weeks and months (>2weeks) and has low propensity to hematogenously seed to extracardiac sites.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 12
Incorrect
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A 5-year-old child is rushed to the emergency department because of fever, erythema and neck stiffness. The child is also hypotensive upon physical examination. Which is the most likely toxin responsible for this child's condition?
Your Answer: Botulinum toxin
Correct Answer: Endotoxin
Explanation: An endotoxin is part of the bacterial outer membrane, and it is not released until the bacterium is killed by the immune system. The body’s response to an endotoxin can involve severe inflammation. In general, the inflammation process is usually considered beneficial to the infected host, but if the reaction is severe enough, it can lead to sepsis.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 13
Incorrect
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A 60-year-old male who was admitted due to cerebrovascular disease on his 5th hospital stay developed pneumonia. The most likely organism that causes hospital acquired pneumonia is pseudomonas aeruginosa. What is the most likely mechanism for the pathogenesis on pseudomonas infection?
Your Answer: Activation of cAMP
Correct Answer: Exotoxin
Explanation:Pseudomonas aeruginosa is a common Gram-negative, rod-shaped bacterium that can cause disease in plants and animals, including humans. It is citrate, catalase, and oxidase positive. P. aeruginosa uses the virulence factor exotoxin A to inactivate eukaryotic elongation factor 2 via ADP-ribosylation in the host cell, much the same as the diphtheria toxin does. Without elongation factor 2, eukaryotic cells cannot synthesize proteins and necrotise. The release of intracellular contents induces an immunologic response in immunocompetent patients.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 14
Incorrect
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Staphylococcus aureus can be identified in the laboratory based on the clotting of plasma. Which microbial product is responsible for this activity?
Your Answer: Thrombin
Correct Answer: Coagulase
Explanation:Staphylococcus aureus is the most pathogenic species and is implicated in a variety of infections. S. aureus can be identified due to its production of coagulase. The staphylococcal enzyme coagulase will cause inoculated citrated rabbit plasma to gel or coagulate. The coagulase converts soluble fibrinogen in the plasma into insoluble fibrin.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 15
Correct
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An 26-year-old man sought admission due to persistent non-bloody diarrhoea. The patient is HIV-positive. Examination of stool sample showed numerous acid-fast cysts. Which of the following organism is the most likely cause of diarrhoea?
Your Answer: Cryptosporidium parvum
Explanation:Cryptosporidium parvum is one of several species that causes cryptosporidiosis, a parasitic disease of the mammalian intestinal tract. Primary symptoms of C. parvum infection are acute, watery, and non-bloody diarrhoea. C. parvum infection is of particular concern in immunocompromised patients, where diarrhoea can reach 10–15 l per day.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 16
Incorrect
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A 27-year-old HIV patient started on an antifungal agent. Which antifungal agent that inhibits the biosynthesis of fungal ergosterol was given to the patient?
Your Answer: Griseofulvin
Correct Answer: Ketoconazole
Explanation:Ketoconazole is a synthetic imidazole antifungal drug used primarily to treat fungal infections. It inhibits the biosynthesis of ergosterol by blocking demethylation at the C14 site of the ergosterol precursor. Amphotericin B and Nystatin impair permeability of the cell membrane. Flucytosine interferes with DNA synthesis, while the target of griseofulvin is the microtubules
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 17
Correct
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A 60-year-old female has sudden onset of high-grade fever associated with cough with productive rusty-coloured sputum. Chest x-ray showed left-sided consolidation. What is the most accurate test for the diagnosis of this patient?
Your Answer: Sputum culture
Explanation:Sputum culture is used to detect and identify the organism that are infecting the lungs or breathing passages.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 18
Incorrect
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A 17-year-old female was given an antibiotic for a urinary tract infection. After taking the medication the patient developed Steven-Johnson syndrome. Which particular antibiotic usually causes Steven-Johnson syndrome?
Your Answer: Tetracycline
Correct Answer: Sulphonamides
Explanation:Stevens–Johnson syndrome (SJS) is a type of severe skin reaction. The most common cause is certain medications such as lamotrigine, carbamazepine, allopurinol, sulphonamide antibiotics, and nevirapine.
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 19
Correct
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A 7-year old child from a rural setting complains of recurrent abdominal pain. The child is found to have a heavy parasitic infestation and anaemia. Which type of anaemia is most likely seen in this patient?
Your Answer: Iron deficiency anaemia
Explanation:The most common cause of iron deficiency anaemia in children in developing countries is parasitic infection (hookworm, amoebiasis, schistosomiasis and whipworm).
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This question is part of the following fields:
- Microbiology
- Pathology
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Question 20
Correct
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A 35 year-old female developed food poisoning 24H after eating canned food. She complained of abdominal cramps, with nausea and vomiting. Shortly after she suddenly developed weakness, blurring of vision, difficulty in swallowing and breathing. Which of the following organisms is most likely associated with fatal food poisoning?
Your Answer: Clostridium botulinum
Explanation:C. botulinum is a Gram-positive, rod-shaped, spore-forming bacterium. It is an obligate anaerobe, meaning that oxygen is poisonous to the cells. Only botulinum toxin types A, B, E, and F cause disease in humans. Types A, B, and E are associated with foodborne illness. Botulism poisoning can occur due to preserved or home-canned, low-acid food that was not processed using correct preservation times and/or pressure. Signs and symptoms of foodborne botulism typically begin between 18 and 36 hours after the toxin gets into the body, but can range from a few hours to several days, depending on the amount of toxin ingested. Botulinum that is produced by Clostridium botulinum can cause respiratory and muscular paralysis.
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This question is part of the following fields:
- Microbiology
- Pathology
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SESSION STATS - PERFORMANCE PER SPECIALTY
