A patient being treated for tuberculosis is suffering from hearing deterioration. What drug causes this complication?

Correct Answer: A

Rationale: The correct answer is A: Streptomycin. Streptomycin is an aminoglycoside antibiotic used to treat tuberculosis that can cause hearing loss as a side effect. It is known to damage the cochlear and vestibular organs in the inner ear. The other choices, B: Isoniazid, C: Rifampicin, and D: Ethionamide, are not associated with causing hearing deterioration as a side effect. Isoniazid can rarely cause peripheral neuropathy, Rifampicin can lead to hepatotoxicity, and Ethionamide may cause gastrointestinal disturbances, but none of these drugs are known to specifically cause hearing loss.

Correct Answer: A

Rationale: The correct answer is A. Rubella virus has icosahedral type of symmetry due to its spherical shape with 20 faces. This symmetry allows for efficient packaging of genetic material and structural stability. Choice B is incorrect as rubella virus is an ssRNA virus, not ssDNA. Choice C is incorrect as rubella virus does have an envelope derived from the host cell membrane. Choice D is incorrect as rubella virus does have glycoprotein spikes on its surface that aid in host cell recognition and entry.

Correct Answer: D

Rationale: The correct answer is D (All of the above) because different bacteria can cause pneumonia. Streptococcus pneumoniae is the most common cause of community-acquired pneumonia. Mycobacterium tuberculosis causes tuberculosis, which can lead to pneumonia. Pseudomonas aeruginosa is a common cause of hospital-acquired pneumonia. Therefore, all three bacteria can be responsible for causing pneumonia in different contexts. Choices A, B, and C are incorrect because each bacterium individually can cause pneumonia, so selecting only one option would not cover the full spectrum of bacterial causes of pneumonia.

Correct Answer: A

Rationale: The correct answer is A: T-lymphocytes. In skin mycosis, a disorder of cellular immunity indicates a deficiency in T-lymphocytes, which play a crucial role in cell-mediated immunity. T-lymphocytes are responsible for recognizing and destroying infected cells. Reduction in T-lymphocytes impairs the body's ability to fight fungal infections. Incorrect choices: B: Immunoglobulin G - Immunoglobulin G is involved in humoral immunity, not cellular immunity. C: Immunoglobulin E - Immunoglobulin E is typically associated with allergic responses, not cellular immunity. D: B-lymphocytes - B-lymphocytes are responsible for producing antibodies in humoral immunity, not directly involved in cell-mediated immunity.

Correct Answer: A

Rationale: Subcutaneous mycoses are fungal infections that affect the skin, subcutaneous tissues, and bones. The correct answer is A: tropics, as these infections are more commonly found in warm and humid regions. Fungi that cause subcutaneous mycoses thrive in tropical climates due to the favorable conditions for their growth and transmission. Choices B, C, and D are incorrect because deserts (B) have dry conditions not conducive to fungal growth, forests of the Northern Hemisphere (C) have varying climates that may not support the specific fungi causing subcutaneous mycoses, and the Rocky Mountains (D) are not typically associated with the high humidity required for these infections.

Correct Answer: A

Rationale: The correct answer is A: 96% ethanol. In Gram's staining method, after applying gentian violet, Lugol's solution, and aqueous fuchsin, the next step is to use a decolorizing agent like 96% ethanol to wash away the excess stain from the Gram-negative bacteria. This step is crucial as it helps differentiate between Gram-positive and Gram-negative bacteria based on their cell wall properties. The other choices are incorrect because sulfuric acid is not used in Gram's staining method, methylene blue is typically used in other staining techniques like the simple stain, and carbolic fuchsin is not a standard reagent in the Gram's staining process.

Correct Answer: B

Rationale: The correct answer is B: intravenous administration. This route bypasses the first-pass metabolism, allowing the drug to directly enter the bloodstream for immediate distribution. In contrast, on the skin (A) and sublingual (D) routes have slower absorption rates due to barriers like skin layers or mucous membranes. Intramuscular (C) absorption is slower than intravenous due to slower perfusion rates in muscle tissues. Overall, intravenous administration provides the fastest and most direct route for drug absorption, making it the most rapid method.

Correct Answer: B

Rationale: Facultative anaerobes can switch between aerobic and anaerobic metabolism based on oxygen availability. This flexibility enables them to grow in both oxygen-rich and oxygen-poor environments, making choice B correct. Choice A is incorrect because facultative anaerobes do not require oxygen for survival. Choice C is incorrect as obligate anaerobes cannot grow in the presence of oxygen. Choice D is incorrect because obligate anaerobes cannot tolerate any amount of oxygen.

Correct Answer: B

Rationale: Step-by-step rationale: 1. Monotrichous means having a single flagellum at one end. 2. The term "polar" indicates that the flagellum is located at one end of the bacterium. 3. Therefore, bacteria with a single polar flagellum are referred to as monotrichous. 4. Choice A is a typo, as it is the same as the correct answer B. Summary: - Choice A is a typo, as it duplicates the correct answer. - Choice C, amphitrichous, refers to bacteria with a flagellum at each end. - Choice D, peritrichous, describes bacteria with flagella distributed over the entire surface.