On examination of a patient with disease onset 5 days ago the doctor suspected tularemia and prescribed the patient tularin intracutaneously. What is the purpose of this drug administration in the patient?

Correct Answer: C

Rationale: The correct answer is C: Treatment. Tularin is a specific immunizing agent used for the treatment of tularemia. The purpose of tularin administration in this patient is to provide a targeted treatment against the suspected tularemia infection. It helps the patient's immune system to recognize and fight against the bacteria causing the disease. Explanation for other choices: A: Allergy diagnostics - Tularin is not used for allergy diagnostics, as it is specifically indicated for tularemia treatment. B: Prognosis for the disease - Tularin is not used to predict the outcome of the disease but rather to treat the infection. D: Treatment evaluation - Tularin is not used for evaluating the effectiveness of treatment but for actively treating the tularemia infection.

Correct Answer: D

Rationale: The correct answer is D because a fourfold increase in titer in the second serum sample indicates a significant rise in specific antibodies, which is crucial for diagnosing viral infections accurately. This increase is considered significant in serologic reactions as it shows a strong antibody response to the virus. A: A threshold increase may not be substantial enough to confirm a diagnostic antibody response. B: Dismissing the increase in titer would overlook important diagnostic information. C: A twofold increase may not be as indicative of a strong antibody response compared to a fourfold increase.

Correct Answer: A

Rationale: The correct answer is A: Protein synthesis. Bacterial ribosomes are responsible for translating mRNA into proteins through a process called translation. This is a crucial step in gene expression, where amino acids are assembled into polypeptide chains. Choice B (DNA replication) is incorrect because ribosomes are not involved in DNA replication. Choice C (Flagella formation) is incorrect as ribosomes do not play a direct role in flagella formation. Choice D (Toxin production) is incorrect as ribosomes are not directly involved in producing toxins.

Correct Answer: D

Rationale: The correct answer is D: icosahedral structure. Icosahedral symmetry is common in viruses due to its efficient packing of genetic material. It consists of 20 equilateral triangular faces and 12 vertices. This symmetry allows viruses to have a stable structure and optimal capacity for encapsulating their genetic material. A: Tetrahedral structure is incorrect as it consists of 4 faces and is not commonly found in viruses. B: Hexahedral structure is incorrect as it consists of 6 faces and is not a common symmetry type in viruses. C: Dodecahedral structure is incorrect as it consists of 12 faces and is not typically seen in viruses. In summary, the icosahedral structure is the correct choice due to its stability, efficient packing, and common presence in viral structures compared to the other options.

Correct Answer: A

Rationale: The correct answer is A (25-37 °C) because mesophilic bacteria thrive best at moderate temperatures typical of most environments, making 25-37 °C their optimum range. This range allows for optimal enzyme activity and growth. Choice B (55-65 °C) is incorrect as it is more suitable for thermophilic bacteria. Choice C (15-18 °C) is too low for mesophiles to thrive efficiently. Choice D (38-45 °C) is too high and is more suitable for thermophiles. Ultimately, the correct answer aligns with the typical temperature range where mesophilic bacteria are most active and abundant.

Correct Answer: B

Rationale: The correct answer is B: Pseudomonas aeruginosa. P. aeruginosa is known for producing pyocyanin, a green pigment. This bacterium is commonly associated with infections in immunocompromised individuals. Staphylococcus aureus (choice A) produces golden-yellow pigments, not green. Escherichia coli (choice C) and Clostridium difficile (choice D) do not produce pyocyanin. Therefore, the correct choice is B based on the characteristic pigment produced by Pseudomonas aeruginosa.

Correct Answer: D

Rationale: The correct answer is D: rRNA. Bacterial ribosomes consist mainly of ribosomal RNA (rRNA), which plays a crucial role in protein synthesis. Ribosomes are composed of rRNA and proteins, with rRNA being the major component. rRNA serves as the structural and catalytic component of the ribosome, aiding in the binding of mRNA and tRNA during translation. Carbohydrates (A) and lipids (B) are not primary components of ribosomes, and DNA (C) is not found in ribosomes as they are involved in storing genetic information, not in protein synthesis.

Correct Answer: B

Rationale: The correct answer is B: RG2. RG2 is appropriate for agents associated with human disease that pose a moderate health risk. These agents may cause disease of varying severity, but generally do not result in serious health consequences. Other choices are incorrect because: A: RG1 is for agents not associated with disease in healthy adults, C: RG3 is for agents associated with serious or lethal human disease, and D: RG4 is for agents that pose a high risk of life-threatening disease and for which there are no treatments.

Correct Answer: D

Rationale: The correct answer is D: Rifampicin. Rifampicin is a first-line antibiotic for treating pulmonary tuberculosis due to its high efficacy against Mycobacterium tuberculosis. It works by inhibiting bacterial RNA synthesis. Furasolidone (A) is not commonly used for tuberculosis, Bactrim (B) is not a first-line drug for tuberculosis, and Streptocide (C) is not as effective as Rifampicin.