microbiology an introduction test bank

Correct Answer: B

Rationale: The correct answer is B: pertussis toxin. This toxin is the most important virulence factor of Bordetella pertussis because it plays a key role in causing the characteristic symptoms of whooping cough. Pertussis toxin interferes with the host's immune response, leading to inflammation and tissue damage in the respiratory tract. The other choices (A: the flagellum, C: P fimbriae, D: mannose-resistant adhesins) are important for bacterial attachment and colonization, but they do not directly contribute to the severity of the disease like pertussis toxin does.

Correct Answer: C

Rationale: Rationale: 1. Psychrophilic: Grow best in cold temperatures 2. Mesophilic: Grow best in moderate temperatures 3. Thermophilic: Grow best in high temperatures - Choice A is incorrect as "thermophobic" is not a recognized term. - Choice B is incorrect as "psychophobic" is not a recognized term. - Choice D is incorrect as "mesophobic" is not a recognized term.

Correct Answer: C

Rationale: Rationale: Metronidazole is the drug of choice for systemic amebiasis due to its high efficacy against Entamoeba histolytica. It has good tissue penetration and can treat intestinal, liver, and lung involvement. Quiniofone (A) has limited use and is not recommended for amebiasis. Enteroseptol (B) is not effective against systemic amebiasis. Tetracycline (D) is not the first-line treatment for amebiasis and has limited efficacy against Entamoeba histolytica.

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.

Correct Answer: C

Rationale: The correct answer is C: Bacterial adhesion to the surface of the host cells, conjugation. Villi and cilia on the cell surface of pathogenic bacteria help in bacterial adhesion to host cells, facilitating the process of infection. Conjugation is the transfer of genetic material between bacterial cells, which can be aided by these structures. The other choices are incorrect because RNA exchange between cells (A) is typically facilitated by different structures like pili, inhibition of complement activity (B) is not related to the function of villi and cilia, and resistance to antibody opsonization (D) is usually achieved through other mechanisms such as capsule formation.