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: A

Rationale: The correct answer is A: Hantavirus. Hantavirus is considered a newly emerging disease because it was first identified in the late 20th century. It is transmitted to humans through rodents and can lead to severe respiratory illness. Malaria, Tuberculosis, and Chlamydia are not considered newly emerging diseases as they have been known for centuries and continue to be prevalent worldwide. Therefore, based on the timeline of discovery and emergence, Hantavirus is the most recent infectious disease among the options provided.

Correct Answer: A

Rationale: The correct answer is A: Escherichia coli. E. coli is a Gram-negative rod that ferments lactose. It is a common cause of gastroenteritis presenting with fever and diarrhea. Salmonella typhi does not ferment lactose and causes typhoid fever. Shigella dysenteriae causes dysentery and does not ferment lactose. Proteus vulgaris does not typically cause gastroenteritis and is not known for lactose fermentation.

Correct Answer: C

Rationale: The correct answer is C: plasmids. Plasmids are nonchromosomal DNA molecules commonly found in bacterial cells, providing additional genetic material for bacteria. They are not essential for bacterial survival but can confer advantages such as antibiotic resistance. Endospores (A) are dormant bacterial structures resistant to harsh conditions. Transposons (B) are mobile genetic elements that can move within a genome. Prions (D) are misfolded proteins causing neurodegenerative diseases, not DNA molecules.

Correct Answer: C

Rationale: The correct answer is C: gram-negative bacteria have an outer membrane that acts as an extra barrier. This outer membrane in gram-negative bacteria contains lipopolysaccharides and porins, which restrict the entry of antibiotics like penicillin. The outer membrane acts as an additional layer of protection, making it harder for penicillin to penetrate and reach its target, the peptidoglycan layer. Choices A, B, and D do not directly address the specific mechanism of resistance seen in gram-negative bacteria. Choice A focuses on transpeptidase enzyme quantity, which is not the primary reason for penicillin resistance. Choice B refers to β-lactamase enzymes in the periplasmic space, which are actually enzymes that degrade penicillin and contribute to resistance, but this is not unique to gram-negative bacteria. Choice D mentions a thicker cell wall, which is a characteristic of gram-positive bacteria, not gram-negative bacteria.