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: B

Rationale: The correct answer is B because there are two types of herpes simplex virus: HSV-1 and HSV-2. HSV-1 typically causes oral herpes, while HSV-2 usually causes genital herpes. Choice A is incorrect because there is more than one type. Choices C and D are also incorrect as there are only two types of herpes simplex virus known to infect humans.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Family Retroviridae is known for having a single-stranded RNA genome. 2. The (-) sign indicates that the RNA strand is negative-sense. 3. Therefore, the correct answer A, "Their capsid consists of two copies of ssRNA(-)," is accurate. Summary: - Choice B is incorrect because Retroviridae have simple type of symmetry. - Choice C is incorrect as Retroviridae are not enveloped viruses. - Choice D is incorrect because Retroviridae are enveloped viruses.

Correct Answer: D

Rationale: The correct answer is D: Ancylostoma duodenale. A scolex is a structure found in tapeworms, not in the other options which are roundworms. Ancylostoma duodenale is a species of hookworm, a type of intestinal parasite that has a distinct scolex with hook-like mouthparts for attachment to the host's intestinal wall. Enterobius vermicularis is a pinworm, Necator americanus is a hookworm species without a scolex, and Ascaris lumbricoides is a roundworm with a cylindrical body lacking a scolex. Therefore, the presence of a scolex specifically points to Ancylostoma duodenale.

Correct Answer: A

Rationale: The presence of acid-fast bacilli stained red using the Ziehl-Neelsen method indicates a mycobacterial infection. Among the choices, tuberculosis is the most common mycobacterial infection affecting the lungs, presenting with acid-fast bacilli in sputum. Leprosy is caused by Mycobacterium leprae, but it typically does not show up in sputum smears. Diphtheria is caused by Corynebacterium diphtheriae, which is not acid-fast. Pneumonia is a general term for lung inflammation caused by various pathogens, not specifically mycobacteria. Therefore, the correct diagnosis is tuberculosis based on the microscopy findings.

Correct Answer: C

Rationale: The correct answer is C: Staphylococcus aureus. This bacterium is commonly associated with hospital-acquired infections due to its ability to cause a wide range of infections and its resistance to multiple antibiotics. Staphylococcus aureus can cause skin infections, pneumonia, bloodstream infections, and surgical site infections, making it a significant threat in healthcare settings. Escherichia coli (choice A) is more commonly associated with foodborne illnesses. Clostridium difficile (choice B) is known for causing antibiotic-associated diarrhea. Bacillus anthracis (choice D) is primarily associated with anthrax infections, which are not typically acquired in hospital settings.

Correct Answer: C

Rationale: The correct staining technique for sputum smears obtained from a tuberculosis patient is Ziehl-Neelsen staining. This technique uses carbol fuchsin dye to stain the acid-fast bacteria, such as Mycobacterium tuberculosis, red. Here's a step-by-step rationale: 1. Ziehl-Neelsen staining is specifically designed to detect acid-fast bacteria like Mycobacterium tuberculosis. 2. Carbol fuchsin dye is used to penetrate the mycolic acid layer in the cell wall of the bacteria, making them resistant to decolorization. 3. Acid-alcohol is used as a decolorizer to remove the stain from non-acid-fast bacteria. 4. Methylene blue is used as a counterstain to visualize non-acid-fast bacteria in blue. Therefore, Ziehl-Neelsen staining is the most appropriate technique for identifying Mycobacterium tuberculosis in sputum smears. Other choices like Gram, Giemsa, and

Correct Answer: A

Rationale: The correct answer is A because most bacteria can grow in both the presence and absence of oxygen. Some bacteria are aerobic and require oxygen for growth, while others are anaerobic and can grow in the absence of oxygen. Choice B is incorrect because not all bacteria grow in the absence of oxygen. Choice C is incorrect because not all bacteria are microaerophiles, which are bacteria that require a low level of oxygen for growth. Choice D is incorrect because most bacteria exhibit flexibility in their oxygen requirements.

Correct Answer: A

Rationale: Step 1: The patient's symptoms align with tetanus infection, such as muscle spasms and fever. Step 2: Tetanus is caused by Clostridium tetani bacteria found in soil. Step 3: The wound from tilling soil provides an entry point for the bacteria. Step 4: Delayed seeking medical attention increases the risk of tetanus development. Step 5: Tetanus toxin affects the nervous system, leading to muscle stiffness and spasms. Summary: Choice A is correct due to symptom alignment, bacterial source, wound type, delayed treatment, and specific neurological effects. Choices B, C, and D lack these specific connections to the given scenario.