Nokea
Cytomegalovirus infections are caused by the human herpesvirus:
- A. 2
- B. 3
- C. 4
- D. 5
Correct Answer: D
Rationale: The correct answer is D because Cytomegalovirus infections are caused by human herpesvirus 5, also known as Human Herpesvirus 5 (HHV-5) or Cytomegalovirus (CMV). This virus belongs to the Herpesviridae family, genus Betaherpesvirinae. Options A, B, and C are incorrect as they do not correspond to the specific virus responsible for causing Cytomegalovirus infections.
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Microscopic examination of a Gramstained scrape from patient's tongue revealed oval, round, elongated chains of dark-violet gemmating cells. What disease can be caused by this causative agent?
- A. Candidosis
- B. Actinomycosis
- C. Diphtheria
- D. Staphylococcic infection
Correct Answer: A
Rationale: Step 1: Oval, round, elongated chains of gemmating cells indicate yeast-like budding cells seen in Candida species.
Step 2: Candidosis is caused by Candida species, which is commonly found in the oral cavity and can cause infections on the tongue.
Step 3: Candidosis presents as white patches or plaques on the tongue.
Step 4: Therefore, the correct answer is A: Candidosis.
Summary:
B: Actinomycosis is caused by Actinomyces species, which are filamentous bacteria, not oval budding cells.
C: Diphtheria is caused by Corynebacterium diphtheriae, which appears as gram-positive rods in chains, not oval budding cells.
D: Staphylococcal infections are caused by Staphylococcus species, which appear as clusters of cocci, not oval budding cells.
Which of the following bacteria is known for causing Lyme disease?
- A. Borrelia burgdorferi
- B. Clostridium difficile
- C. Streptococcus pneumoniae
- D. Mycobacterium tuberculosis
Correct Answer: A
Rationale: The correct answer is A: Borrelia burgdorferi. This bacterium is known for causing Lyme disease, which is transmitted through tick bites. Borrelia burgdorferi is specifically associated with Lyme disease due to its ability to infect and spread within the body, leading to a range of symptoms if left untreated.
Summary of incorrect choices:
B: Clostridium difficile - Known for causing gastrointestinal infections, not Lyme disease.
C: Streptococcus pneumoniae - Commonly causes pneumonia and other respiratory infections, not Lyme disease.
D: Mycobacterium tuberculosis - Causes tuberculosis, a respiratory disease, not Lyme disease.
On the territory of a certain region the mass death of rodents was observed. It was assumed that it may be caused by plague agent. What serological reaction should be applied for quick determination of antigen of this epizootic agent?
- A. Precipitation reaction
- B. Agglutination reaction
- C. Reaction of passive hemagglutination
- D. Bordet-Gengou test
Correct Answer: B
Rationale: The correct answer is B: Agglutination reaction. This is the most suitable serological reaction for the quick determination of the antigen of the epizootic agent causing mass rodent deaths. In agglutination reaction, antibodies cause the clumping of antigens, allowing for easy visual detection of the presence of the specific antigen. This is efficient for rapid diagnosis in cases of suspected infectious diseases like plague.
A: Precipitation reaction is more suitable for identifying soluble antigens, not for quick determination of a specific antigen in this scenario.
C: Reaction of passive hemagglutination is used for measuring the presence of antibodies, not antigens.
D: Bordet-Gengou test is a specific test for the identification of Bordetella pertussis bacterium, not suitable for this scenario.
A patient with abdominal pain had a stool culture revealing non-lactose-fermenting, Gram-negative rods that produced gas in a nutrient broth. What is the most likely causative agent?
- A. Salmonella typhi
- B. Shigella dysenteriae
- C. Escherichia coli
- D. Proteus vulgaris
Correct Answer: D
Rationale: The correct answer is D: Proteus vulgaris. This is because Proteus species are non-lactose-fermenting Gram-negative rods that are known to produce gas in nutrient broths. Proteus vulgaris is commonly associated with urinary tract infections and can also cause abdominal infections.
A: Salmonella typhi typically causes typhoid fever and is not known to produce gas in nutrient broths.
B: Shigella dysenteriae is a causative agent of dysentery and does not typically produce gas in nutrient broths.
C: Escherichia coli is a lactose-fermenting bacterium and does not fit the description of the organism in the stool culture.
Microscopy of a sputum smear from a pneumonia patient revealed Gram-positive diplococci with pointed ends surrounded by a capsule. What is the causative agent?
- A. Streptococcus pneumoniae
- B. Klebsiella pneumoniae
- C. Neisseria meningitidis
- D. Staphylococcus aureus
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae.
1. Gram-positive diplococci with pointed ends: characteristic morphology of Streptococcus pneumoniae.
2. Surrounded by a capsule: S. pneumoniae is encapsulated, important for virulence.
3. Klebsiella pneumoniae (B) is a Gram-negative rod, Neisseria meningitidis (C) is a Gram-negative diplococcus, and Staphylococcus aureus (D) is a Gram-positive cocci in clusters, not diplococci.