microbiology an introduction test bank

Correct Answer: C

Rationale: The primary target of beta-lactam antibiotics is cell wall synthesis. These antibiotics inhibit enzymes called penicillin-binding proteins, which are essential for building the bacterial cell wall. By disrupting cell wall synthesis, beta-lactam antibiotics weaken the cell wall, leading to bacterial cell lysis and death. Protein synthesis (Choice A), DNA replication (Choice B), and folic acid synthesis (Choice D) are not directly targeted by beta-lactam antibiotics, making them incorrect choices.

Correct Answer: D

Rationale: The correct answer is D, Shiga anatoxin. This is because the Salk and Sabin vaccines are actually for polio, not chemical vaccines. HPV vaccine is a biological vaccine, not a chemical one. Shiga anatoxin is a chemical vaccine used against Shigella bacteria, making it the only correct choice for chemical vaccines in this question.

Correct Answer: D

Rationale: The correct answer is D. Escherichia coli, Salmonella enterica, and Pseudomonas aeruginosa all produce endotoxins that can lead to septic shock. Endotoxins are part of the outer membrane of Gram-negative bacteria and can trigger a systemic inflammatory response if released into the bloodstream. E. coli and Salmonella are common causes of bacterial infections that can lead to septic shock, while P. aeruginosa is a known opportunistic pathogen that can produce endotoxins. Therefore, all three bacteria can cause septic shock by releasing endotoxins. Choices A, B, and C are incorrect because each of these bacteria individually can produce endotoxins that contribute to the development of septic shock.

Correct Answer: D

Rationale: Step 1: Mantoux test measures cell-mediated immunity response to tuberculosis. Step 2: A negative result means no significant immune response to TB antigens. Step 3: Option A is incorrect, as it refers to antitoxic immunity, not cell immunity. Step 4: Option B is incorrect, as it mentions antibodies, not cell-mediated immunity. Step 5: Option C is incorrect, as it states absence of antibodies, not cell immunity. Step 6: Option D is correct as it directly correlates with the purpose of Mantoux test.

Correct Answer: B

Rationale: Answer B, Infectious mononucleosis, is not caused by enteroviruses. Infectious mononucleosis is primarily caused by the Epstein-Barr virus, a member of the herpesvirus family, not by enteroviruses. Enteroviruses are known to cause diseases such as myocarditis, herpangina, and Boston exanthema. Therefore, B is the correct answer. Myocarditis, herpangina, and Boston exanthema can all be caused by enteroviruses, making choices A, C, and D incorrect, respectively.