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Microscopic examination of a smear from a chancre revealed spiral microorganisms. The bacteria were thin and mobile with 8-12 regular coils. What is the likely diagnosis?
- A. Syphilis
- B. Leptospirosis
- C. Lyme disease
- D. Relapsing fever
Correct Answer: A
Rationale: The correct diagnosis is A: Syphilis. The spiral microorganisms described are characteristic of Treponema pallidum, the causative agent of syphilis. The thin and mobile bacteria with 8-12 regular coils match the morphology of Treponema pallidum. Leptospirosis is caused by Leptospira interrogans, which are thicker and have hook-like ends, different from the described bacteria. Lyme disease is caused by Borrelia burgdorferi, which has a different appearance than the thin, coiled bacteria in the smear. Relapsing fever is caused by Borrelia recurrentis, which typically have irregular coils, unlike the regular coils seen in the smear.
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Examination of a smear from a chancre revealed mobile, long, spiral microorganisms with 8-12 regular coils. What is the causative agent?
- A. Treponema
- B. Leptospira
- C. Borrelia
- D. Vibrios
Correct Answer: A
Rationale: The correct answer is A: Treponema. The characteristics described match Treponema pallidum, the causative agent of syphilis. Treponema has long, spiral shape with 8-12 regular coils. Leptospira (B) is a spirochete but has fewer coils and causes leptospirosis. Borrelia (C) is another spirochete but typically has irregular coils and causes Lyme disease. Vibrios (D) are curved rods and not spirochetes.
Allergy to penicillin is an example of:
- A. Type I hypersensitivity reaction
- B. Type II hypersensitivity reaction
- C. Type III hypersensitivity reaction
- D. Type IV hypersensitivity reaction
Correct Answer: A
Rationale: Step-by-step rationale for choice A being correct:
1. Penicillin allergy involves IgE antibodies binding to penicillin.
2. This triggers mast cell degranulation, releasing histamine.
3. Histamine causes allergic symptoms like rash, swelling.
4. This immune response characterizes Type I hypersensitivity reactions.
Summary of other choices:
B: Type II reactions involve antibody-mediated cell destruction, not seen in penicillin allergy.
C: Type III reactions involve immune complex deposition, not typical in penicillin allergy.
D: Type IV reactions are delayed hypersensitivity reactions, not immediate like penicillin allergy.
Which statement for immunomodulators is correct
- A. they can only stimulate the incomplete humoral and immune response
- B. Isoniazid is a very effective immunomodulator
- C. they can be natural and artificial compounds
- D. they can only suppress the incomplete humoral and immune response
Correct Answer: C
Rationale: Rationale:
Choice C is correct because immunomodulators can indeed be natural (e.g., cytokines) or artificial compounds (e.g., synthetic peptides). They work by modulating the immune response, enhancing or suppressing it as needed.
Choice A is incorrect because immunomodulators can stimulate both humoral and cellular immune responses.
Choice B is incorrect as isoniazid is primarily an antibiotic used to treat tuberculosis, not an immunomodulator.
Choice D is incorrect because immunomodulators can have varying effects on the immune response, not just suppress it.
When using gram staining method fungi stain:
- A. Blue-purple
- B. Red
- C. Silver
- D. Do not stain
Correct Answer: D
Rationale: The correct answer is D: Fungi do not stain in the gram staining method because they have a unique cell wall composition different from bacteria. Fungi have chitin in their cell walls, which is not easily stained by the gram staining process. This method primarily targets the peptidoglycan layer present in bacterial cell walls. Therefore, fungi will not take up the stain and will remain colorless. The other choices (A: Blue-purple, B: Red, C: Silver) are incorrect because they describe colors that are associated with staining results for bacteria, not fungi.
After consumption some tinned meat a patient had diplopia, acute headache, deglutition disorder, hard breathing, muscle weakness. The diagnosis was botulism. What factor of pathogenicity are the clinic presentations of this disease connected with?
- A. Exotoxin B.Hemolysin C.Endotoxin D.Plasmocoagulase E.Fibrinolysin
Correct Answer: A
Rationale: The correct answer is A, Exotoxin. Botulism is caused by the exotoxin produced by Clostridium botulinum bacteria. The symptoms described - diplopia, acute headache, deglutition disorder, hard breathing, muscle weakness - are all consistent with botulism due to the neurotoxic effects of the exotoxin. The exotoxin interferes with neurotransmission at the neuromuscular junction, leading to muscle paralysis and the symptoms mentioned. The other choices (B, C, D, E) are incorrect as they do not correspond to the pathogenic mechanism of botulism and do not explain the specific clinical manifestations observed in this case.