Which bacteria is responsible for causing the disease known as leprosy?

Correct Answer: A

Rationale: The correct answer is A: Mycobacterium leprae. This bacterium is responsible for causing leprosy. Mycobacterium leprae is a slow-growing bacterium that affects the skin and nerves, leading to the characteristic symptoms of leprosy. Neisseria gonorrhoeae is a sexually transmitted bacterium causing gonorrhea. Streptococcus pneumoniae causes pneumonia and other respiratory infections. Clostridium perfringens is associated with food poisoning and gas gangrene. Therefore, the correct answer is A because Mycobacterium leprae specifically causes leprosy, while the other choices are associated with different diseases.

Correct Answer: D

Rationale: The correct answer is D because the defense role of the skin is not related to lysozyme activity. Lysozyme is an enzyme found in tears, saliva, and mucus, not specifically in the skin. The skin's defense role is primarily related to its physical barrier function, low pH creating an acidic environment that inhibits microbial growth, secretion of antimicrobial peptides, and the activity of skin macrophages that phagocytose pathogens. Choices A, B, and C are true statements as they correctly describe different aspects of the skin's defense mechanisms.

Correct Answer: A

Rationale: The correct answer is A: Mycobacterium leprae. This bacterium is responsible for causing leprosy. Mycobacterium leprae is a slow-growing bacterium that affects the skin and nerves, leading to the characteristic symptoms of leprosy. Neisseria gonorrhoeae is a sexually transmitted bacterium causing gonorrhea. Streptococcus pneumoniae causes pneumonia and other respiratory infections. Clostridium perfringens is associated with food poisoning and gas gangrene. Therefore, the correct answer is A because Mycobacterium leprae specifically causes leprosy, while the other choices are associated with different diseases.

Correct Answer: C

Rationale: Correct Answer: C: dermatophytes Rationale: 1. Dermatophytes are fungi that specifically infect the skin, hair, and nails. 2. They are the most common fungi causing such infections in humans. 3. Plasmodium and sporozoites are parasites causing malaria, not skin diseases. 4. Nematodes are a type of roundworm and do not typically cause skin, hair, or nail infections. In summary, dermatophytes are the correct answer because they are specialized fungi that commonly cause skin, hair, and nail diseases, distinguishing them from the other choices.

Correct Answer: A

Rationale: The correct answer is A: Spores. The Ozheshko method is used to stain spores, which are resistant structures produced by certain bacterial species. By studying the smear of streptobacillus preparation under oil immersion, one can observe the presence of spores as distinct, oval bodies within the bacteria. Spores are important for bacterial survival in harsh conditions. Summary: B: Capsules are not typically stained using the Ozheshko method. Capsules are usually visualized using negative staining techniques. C: Flagella are not stained by the Ozheshko method. Flagella are visualized using special staining techniques like the flagella stain. D: Inclusions are not specifically stained by the Ozheshko method. Inclusions are often observed using techniques that highlight cellular structures or components.

Correct Answer: B

Rationale: Step-by-step rationale: 1. Marburg virus is named after the German city Marburg where it was first identified in 1967. 2. Chikungunya virus is named after a village in Tanzania. 3. Measles virus got its name from the Middle English word "maselen" meaning "many little spots". 4. Epstein-Barr virus is named after Michael Epstein and Yvonne Barr, who discovered it. Summary: B is correct as it is directly named after the city of its discovery. A, C, and D are incorrect as they are named after other locations, characteristics, or discoverers.

Correct Answer: A

Rationale: The correct answer is A: Botulism. Botulism is a rare but serious illness caused by a toxin produced by the bacterium Clostridium botulinum. In this case, the patient's symptoms align with botulism due to the ingestion of homemade mushrooms. The symptoms of double vision, heavy breathing, paleness, widened pupils, swallowing difficulties, bradycardia, and constipation are all classic signs of botulism poisoning. The toxin affects the nervous system and can lead to paralysis. The other choices (B: Yersiniosis, C: Leptospirosis, D: Salmonellosis) do not match the patient's symptoms and history of consuming mushrooms, making them incorrect.

Correct Answer: D

Rationale: Interferon delta is not a known type of interferon, making choice D incorrect. Interferon beta is indeed produced by fibroblasts (choice A), interferon alpha by leukocytes (choice B), and interferon gamma by lymphocytes (choice C). Each type of interferon is produced by specific cells in the immune system, contributing to the body's defense against viruses and other pathogens.

Correct Answer: B

Rationale: The correct answer is B: Gram-negative bacteria. Gram-negative bacteria have an outer membrane containing lipopolysaccharides (LPS). In the Gram staining technique, these bacteria appear pink/red due to the thin peptidoglycan layer, which allows the crystal violet stain to be washed out, revealing the safranin counterstain. Gram-positive bacteria (choice A) have a thick peptidoglycan layer but lack an outer membrane with LPS. Choice C is incorrect since only Gram-negative bacteria possess LPS in their outer membrane. Choice D is incorrect as all bacteria can be classified as either Gram-positive or Gram-negative based on their cell wall structure.