Nokea
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.
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Which of the following bacteria is associated with stomach ulcers?
- A. Escherichia coli
- B. Helicobacter pylori
- C. Bacillus cereus
- D. Clostridium difficile
Correct Answer: B
Rationale: The correct answer is B: Helicobacter pylori. This bacterium is associated with stomach ulcers as it can survive in the acidic environment of the stomach and produce substances that weaken the stomach lining. Escherichia coli (A) is associated with foodborne illnesses, not ulcers. Bacillus cereus (C) causes food poisoning. Clostridium difficile (D) is associated with antibiotic-associated colitis, not ulcers. Therefore, Helicobacter pylori is the correct answer based on its specific association with stomach ulcers.
Poxviruses are DNA viruses that replicate in the cytoplasm.
- A. TRUE
- B. FALSE
- C. Partially
- D. Not Sure
Correct Answer: A
Rationale: Step 1: Poxviruses are indeed DNA viruses, confirmed by scientific research.
Step 2: Poxviruses replicate entirely in the cytoplasm, unlike most DNA viruses.
Step 3: Cytoplasmic replication is a unique characteristic of poxviruses.
Step 4: The replication process of poxviruses in the cytoplasm is well-documented.
Step 5: Therefore, option A (TRUE) is correct, as poxviruses replicate in the cytoplasm exclusively.
Which of the following bacteria is known for producing a toxin that causes botulism?
- A. Clostridium botulinum
- B. Clostridium tetani
- C. Staphylococcus aureus
- D. Neisseria gonorrhoeae
Correct Answer: A
Rationale: The correct answer is A: Clostridium botulinum. This bacterium is known for producing botulinum toxin, which causes botulism. It is an anaerobic, spore-forming bacterium commonly found in soil. Clostridium tetani causes tetanus, not botulism. Staphylococcus aureus can cause food poisoning but not botulism. Neisseria gonorrhoeae is responsible for gonorrhea, not botulism. Therefore, A is the correct answer due to the specific association of Clostridium botulinum with botulism toxin production.
Which of the following viruses could be reactivated under immunosuppressive therapy?
- A. Virus Parotitidis
- B. Rubella virus
- C. Influenza A
- D. None of the above
Correct Answer: D
Rationale: The correct answer is D, "None of the above," because viruses like Parotitidis (mumps), Rubella, and Influenza A are not typically associated with reactivation under immunosuppressive therapy. Reactivation is more commonly seen in latent viruses like herpesviruses (e.g., herpes simplex, varicella-zoster), cytomegalovirus, and Epstein-Barr virus. These viruses can remain dormant in the body and reactivate when the immune system is compromised. Therefore, the correct answer is D, as the viruses mentioned in choices A, B, and C do not fit the criteria for reactivation under immunosuppressive therapy.
A journalist's body temperature has sharply increased in the morning three weeks after his mission in India, it was accompanied with shivering and bad headache. A few hours later the temperature decreased. The attacks began to repeat in a day. He was diagnosed with tropical malaria. What stage of development of Plasmodium is infective for anopheles-female?
- A. Gametocytes
- B. B.Shizontes
- C. C.Merozoites
- D. E.Sporozoites
Correct Answer: D
Rationale: The correct answer is D: Sporozoites. Sporozoites are the infective stage of Plasmodium for the female Anopheles mosquito. Here's the rationale: After being transmitted to a human host through a mosquito bite, the sporozoites travel to the liver where they mature and reproduce asexually as merozoites (not the infective stage for mosquitoes). The merozoites then infect red blood cells, leading to symptoms like fever, headache, and shivering. During the blood stage, some merozoites develop into male and female gametocytes, which are not infective to mosquitoes. When a mosquito bites an infected person, it ingests gametocytes, which then develop into male and female gametes and fuse to form ookinetes. Ookinetes develop into oocysts in the mosquito's gut, releasing sporozoites that migrate to the salivary glands, ready to infect a new human host when the mosquito bites