Nokea
In serologic reactions used in virology, a diagnostic antibody response should be taken into account if:
- A. A threshold increase in the titer in the second serum sample is observed
- B. The increase of the titer has no diagnostic significance for viral infections
- C. Two fold increase in the titer in the second serum sample is observed
- D. A fourfold increase in the titer in the second serum sample is observed
Correct Answer: D
Rationale: The correct answer is D because a fourfold increase in titer in the second serum sample indicates a significant rise in specific antibodies, which is crucial for diagnosing viral infections accurately. This increase is considered significant in serologic reactions as it shows a strong antibody response to the virus.
A: A threshold increase may not be substantial enough to confirm a diagnostic antibody response.
B: Dismissing the increase in titer would overlook important diagnostic information.
C: A twofold increase may not be as indicative of a strong antibody response compared to a fourfold increase.
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Virulence
- A. Is the degree of pathogenicity
- B. Of the microorganism is not a constant characteristic
- C. Can be measured with LD50
- D. All the answers are true
Correct Answer: D
Rationale: The correct answer is D because virulence refers to the degree of pathogenicity of a microorganism, which can vary and is not a constant characteristic. It can be measured using LD50, which is the lethal dose that kills 50% of the test population. Therefore, all the statements in options A, B, and C are true and collectively provide a comprehensive understanding of virulence.
Which ones of the following symptoms are NOT typical for botulism
- A. descending, flaccid paralysis
- B. dry mouth and difficulty in swallowing and speaking
- C. chills, fever up to 40°C and loss of consciousness
- D. blurred vision, diplopia
Correct Answer: C
Rationale: The correct answer is C because chills, fever, and loss of consciousness are not typical symptoms of botulism. Botulism is characterized by descending, flaccid paralysis (choice A), dry mouth, difficulty swallowing, and speaking (choice B), and blurred vision, diplopia (choice D). These symptoms result from the neurotoxin produced by Clostridium botulinum, leading to muscle weakness and paralysis. Chills, fever, and loss of consciousness are more commonly associated with infections or other conditions, not botulism.
A 45-year-old patient has foul-smelling diarrhea. Stool examination revealed large ciliated protozoa with a kidney-shaped macronucleus. What is the causative agent?
- A. Balantidium coli
- B. Entamoeba histolytica
- C. Giardia lamblia
- D. Trichomonas hominis
Correct Answer: A
Rationale: The correct answer is A: Balantidium coli. This large ciliated protozoa with a kidney-shaped macronucleus is characteristic of Balantidium coli, an intestinal parasite known to cause foul-smelling diarrhea in humans. Balantidium coli is the only option among the choices that fits this specific description. Entamoeba histolytica causes amoebic dysentery, Giardia lamblia causes giardiasis, and Trichomonas hominis is a non-pathogenic protozoa found in the intestinal tract. Therefore, based on the morphology described in the question, Balantidium coli is the correct causative agent.
Which bacterium is known for producing a green pigment called pyocyanin?
- A. Staphylococcus aureus
- B. Pseudomonas aeruginosa
- C. Escherichia coli
- D. Clostridium difficile
Correct Answer: B
Rationale: The correct answer is B: Pseudomonas aeruginosa. P. aeruginosa is known for producing pyocyanin, a green pigment. This bacterium is commonly associated with infections in immunocompromised individuals. Staphylococcus aureus (choice A) produces golden-yellow pigments, not green. Escherichia coli (choice C) and Clostridium difficile (choice D) do not produce pyocyanin. Therefore, the correct choice is B based on the characteristic pigment produced by Pseudomonas aeruginosa.
All is true for bacterial spores EXCEPT:
- A. They can deform the cell or not
- B. They can be terminal, subterminal and central
- C. They are used for cell division
- D. They are formed for 6-8h
Correct Answer: C
Rationale: The correct answer is C. Bacterial spores are NOT used for cell division. Bacterial spores are dormant, resistant forms of bacteria that are formed in response to harsh environmental conditions. They are not involved in cell division but rather serve as a survival mechanism for the bacteria.
A: They can deform the cell or not - This is true. Bacterial spores can deform the cell or not depending on the conditions.
B: They can be terminal, subterminal, and central - This is true. Bacterial spores can be located at different positions within the bacterial cell.
D: They are formed for 6-8h - This is incorrect. The formation of bacterial spores can take variable time periods depending on the species and environmental conditions.