A patient ill with amebiasis was prescribed a certain drug. The use of alcohol together with this drug is contraindicated because the drug inhibits metabolism of ethyl alcohol. What drug is it?

Correct Answer: A

Rationale: Rationale: 1. Metronidazole is known to inhibit aldehyde dehydrogenase, an enzyme involved in alcohol metabolism. 2. Inhibition of this enzyme leads to accumulation of acetaldehyde, causing unpleasant symptoms when alcohol is consumed. 3. This reaction is known as the disulfiram-like reaction. 4. Reserpine, Clonidine, and Diazepam do not have this specific mechanism of action. Summary: - Option A (Metronidazole) is correct due to its inhibition of alcohol metabolism. - Options B, C, and D are incorrect as they do not exhibit this interaction with alcohol metabolism.

Correct Answer: A

Rationale: Step 1: A bacterial colony is a visible formation: Correct as colonies are visible to the naked eye. Step 2: Formed by clustering of cells: Correct as colonies are made up of numerous bacterial cells. Step 3: Belonging to different bacterial species: Correct as colonies can consist of one or multiple species. Summary: Choice A is correct as it accurately describes a bacterial colony. Choice B is incorrect as colonies can also form on solid nutrient mediums. Choice C is incorrect as choice A is correct. Choice D is incorrect as there is a correct option provided.

Correct Answer: A

Rationale: The correct answer is A: Vibrio cholerae. This bacterium produces cholera toxin, an exotoxin that causes severe dehydration and diarrhea by increasing the secretion of electrolytes and water in the intestines. Vibrio cholerae is the causative agent of cholera, a disease characterized by profuse watery diarrhea. Choice B, Clostridium tetani, produces tetanospasmin causing tetanus, not dehydration or diarrhea. Choice C, Escherichia coli, can cause diarrhea but rarely severe dehydration. Choice D, Shigella dysenteriae, produces Shiga toxin leading to bloody diarrhea, not severe dehydration.

Correct Answer: A

Rationale: The correct answer is A: Clostridium perfringens. This is because Clostridium perfringens is a Gram-positive rod bacterium that forms terminal spores. It is commonly associated with deep tissue infections and can cause gas gangrene. Bacillus anthracis (B) causes anthrax and does not typically form spores at the terminal end. Clostridium tetani (C) causes tetanus and Bacillus cereus (D) is more commonly associated with food poisoning. In this case, the presence of terminal spores along with the clinical presentation of a deep tissue infection points towards Clostridium perfringens as the most likely causative agent.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Tuberculosis, Q-fever, and Legionnaires disease all can infect the respiratory tract. Tuberculosis is a bacterial infection affecting the lungs, Q-fever is caused by a bacterium that primarily affects the lungs, and Legionnaires disease is a severe form of pneumonia. All three diseases specifically target the respiratory system, making them the correct choices. Choices A, B, and C are incorrect because each of them individually infects the respiratory tract, not just one or two of them.

Correct Answer: C

Rationale: The correct answer is C: circular double-stranded DNA. Bacterial genomes are typically composed of circular double-stranded DNA due to its stability and efficient replication. Circular DNA allows for continuous replication without the need for telomeres present in linear DNA (choice B). Bacteria do not typically have double-stranded RNA genomes (choice A) as RNA is more commonly found in viruses. Single-stranded DNA (choice D) is not typically the main genetic material in bacteria, as it is less stable and less efficient for information storage compared to double-stranded DNA.

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known to produce a blue-green pigment called pyocyanin, which is characteristic of the organism. Additionally, it has a distinct fruity odor due to the production of certain volatile compounds. Escherichia coli (B) does not produce blue-green pigment or have a fruity odor. Klebsiella pneumoniae (C) and Proteus mirabilis (D) also do not exhibit these specific characteristics associated with Pseudomonas aeruginosa.

Correct Answer: C

Rationale: Granulomatosis infantiseptica is commonly caused by Listeria monocytogenes, a bacterium known to infect newborns. It can lead to granulomatous lesions in various organs. Staphylococcus aureus and Mycobacterium tuberculosis are not typical causes of this condition in infants. Choice D is incorrect as it suggests all listed bacteria are responsible, which is not accurate. Therefore, the correct answer is C as Listeria monocytogenes is the specific pathogen associated with granulomatosis infantiseptica.

Correct Answer: C

Rationale: The correct answer is C: Actinomycosis. Actinomycosis is a chronic suppurative bacterial infection caused by Actinomyces species, which form sulfur granules in purulent masses surrounded by dense fibrous tissue. In this case, the presence of fungal druses, plasma cells, xanthoma cells, and macrophages in the histological examination is characteristic of actinomycosis. The clinical presentation of skin redness, swelling, and abscess formation in the neck area also aligns with actinomycosis. Choice A: Syphilis is caused by Treponema pallidum, presenting with a painless chancre at the site of infection, not skin redness and swelling in the neck area. Choice B: Carbuncle is a bacterial skin infection involving a group of hair follicles, typically on the back of the neck, not characterized by fungal druses or sulfur granules. Choice D: Leprosy