Correct Answer: D

Rationale: The correct answer is D. Staphylococcus aureus, Escherichia coli, and Clostridium difficile are all known for causing hospital-acquired infections. Staphylococcus aureus can cause skin infections and pneumonia. Escherichia coli can lead to urinary tract infections. Clostridium difficile is associated with gastrointestinal infections. Each of these bacteria has been linked to healthcare-associated infections due to their ability to spread in healthcare settings. Therefore, the correct answer is D. Choices A, B, and C are incorrect because each of these bacteria individually is known to cause hospital-acquired infections.

Correct Answer: A

Rationale: The correct answer is A: Neisser. Bacterial capsules can be stained using the Neisser staining method because it specifically targets the capsule, making it visible under a microscope. Neisser staining involves using a combination of acidic and basic dyes to highlight the capsule structure. This method helps differentiate the capsule from the bacterial cell, aiding in the identification and study of capsules. Choices B, C, and D are incorrect because Cleat and Müller staining methods are not commonly used for staining bacterial capsules, and "None of the above" is incorrect as Neisser staining is a valid method for capsule staining.

Correct Answer: A

Rationale: Step-by-step rationale for why Answer A (Sabouraud's) is correct: 1. Sabouraud's agar is a selective medium for fungi. 2. Candida is a type of fungus causing candidosis. 3. Sabouraud's agar promotes fungal growth. 4. Candida will grow on Sabouraud's agar, confirming the diagnosis. 5. Other choices are for bacterial culture, not suitable for fungal growth. Summary: - Endo, Jensen's, and Roux are not appropriate for fungal culture. - Sabouraud's agar specifically supports fungal growth, making it the correct choice for confirming candidosis.

Correct Answer: C

Rationale: Rationale: 1. Candida is a fungus commonly isolated from clinical specimens. 2. Sabouraud agar is the most suitable medium for Candida due to its low pH and high dextrose content. 3. Low pH inhibits bacterial growth, while dextrose promotes fungal growth. 4. Zeisler media, Chocolate agar, and Muller-Hinton agar are not specific for fungal isolation. Summary: - Zeisler media is used for anaerobic bacteria. - Chocolate agar is used for fastidious organisms like Haemophilus. - Muller-Hinton agar is for antibiotic susceptibility testing, not fungal isolation.

Correct Answer: A

Rationale: The correct answer is A: Metronidazole. Amebic dysentery is caused by the parasite Entamoeba histolytica, not a bacterium, hence antibiotics like Chloramphenicol or Phthalazole are ineffective. Metronidazole is the drug of choice for treating amebic dysentery due to its efficacy against anaerobic organisms like Entamoeba histolytica. Furasolidone is used for treating bacterial infections, not parasitic ones like amebiasis. The patient's symptoms of diarrhea, stomach aches, and a recent history of drinking water from a potentially contaminated source in the forest are indicative of a parasitic infection, supporting the choice of Metronidazole for treatment.