Correct Answer: A

Rationale: Step 1: Bordetella pertussis is the causative agent of whooping cough, also known as pertussis. Step 2: This bacterium produces toxins that damage the respiratory tract, leading to severe coughing fits. Step 3: Clostridium tetani causes tetanus, Haemophilus influenzae causes respiratory infections, and Staphylococcus aureus causes skin infections. Step 4: Therefore, A is the correct answer as it is the only bacterium directly associated with whooping cough.

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: Mefloquine. Mefloquine is a histoschizontocidal antimalarial drug commonly prescribed for prevention of malaria in travelers. It is effective against the liver stage of the malaria parasite, which is crucial for preventing the development of the disease. Chingamin (A) is not a commonly used antimalarial drug. Biseptol (C) is a combination antibiotic and is not effective against malaria parasites. Quinine (D) is primarily used for treating malaria, not preventing it, and it is not specifically histoschizontocidal.

Correct Answer: D

Rationale: The correct answer is D: Exanthematous rash. Erythema infectiosum, also known as fifth disease, is characterized by a distinctive rash on the cheeks that looks like a "slapped cheek." This rash then spreads to the rest of the body, resulting in a lace-like rash (exanthem). Swelling of salivary glands (choice A) is not a typical symptom of erythema infectiosum. Diarrhea (choice B) and hepatitis (choice C) are also not associated with this condition. Therefore, the most characteristic clinical symptom of erythema infectiosum is the exanthematous rash.

Correct Answer: A

Rationale: Step 1: Initial diagnosis of influenza suggests a viral illness. Step 2: Presence of maculopapular petechial rash and high fever indicates a systemic infection. Step 3: Symptoms like euphoria, hyperemia, tachycardia, splenomegaly, and excitement are characteristic of epidemic typhus. Step 4: Face hyperemia, sclera reddening, and tongue tremor are specific to epidemic typhus. Step 5: Epidemic typhus is transmitted by body lice, which fits the scenario of a patient without permanent residence. Summary: - Delirium alcoholicum is unlikely due to the specific symptoms and lack of history of alcohol abuse. - Leptospirosis typically presents with jaundice and renal symptoms, not seen in this case. - Measles rash is different from the maculopapular petechial rash described.