microbiology chapter 13 test bank

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas aeruginosa. P. aeruginosa is a Gram-negative rod that is a lactose non-fermenter commonly associated with deep tissue infections. It is an opportunistic pathogen known for its ability to cause infections in immunocompromised individuals. P. aeruginosa is often resistant to multiple antibiotics and can form biofilms, making it difficult to treat. Summary of why other choices are incorrect: B: Escherichia coli is a Gram-negative rod that ferments lactose and is commonly found in the gastrointestinal tract. It is not typically associated with deep tissue infections. C: Salmonella typhi is a Gram-negative rod that causes typhoid fever, primarily affecting the gastrointestinal system, not deep tissue infections. D: Shigella dysenteriae is a Gram-negative rod that causes bacillary dysentery, which primarily affects the gastrointestinal tract and does not typically cause deep tissue infections.

Correct Answer: C

Rationale: Step 1: "Fried egg" colonies typically refer to colonies with a raised center and flattened periphery, resembling the appearance of a fried egg. Step 2: Actinomycetes are filamentous bacteria known to form "fried egg" colonies in nutrient medium. Step 3: Actinomycetes are commonly found in soil and are known to be phytopathogenic microorganisms. Step 4: Actinomycetes produce secondary metabolites with medicinal properties, making them a likely agent from a medicinal herb. Overall, the correct answer is C (Actinomycetes) as they fit the description provided in the question and are commonly associated with the given scenario. The other choices are incorrect as they do not exhibit the specific characteristics mentioned in the question or are not typically associated with forming "fried egg" colonies in nutrient medium.

Correct Answer: C

Rationale: The correct answer is C: heterotrophic. Fungi are heterotrophic organisms that obtain nutrients by absorbing organic compounds from their environment. They do not produce their own food through photosynthesis (option A: autotrophic) or chemosynthesis (option B: chemotrophic). Fungi also do not rely on light for energy (option D: phototrophic). Therefore, the correct choice is C as it accurately describes the nutritional mode of fungi.

Correct Answer: B

Rationale: The correct answer is B: Mycobacterium leprae. This microorganism can only be cultured in the footpads of mice or a species of armadillo due to its specific growth requirements. Mycobacterium tuberculosis (choice A) can be cultured in various culture media in the laboratory. Neisseria gonorrhoeae (choice C) can be cultured on selective media like Thayer-Martin agar. Mycoplasma (choice D) can be cultured in cell cultures or specialized media. Therefore, the unique growth pattern of Mycobacterium leprae makes it the correct answer.

Correct Answer: A

Rationale: The correct answer is A: Hyperresponsiveness reaction type IV. This type of reaction, also known as delayed-type hypersensitivity, is characterized by the activation of T lymphocytes and macrophages, leading to inflammation at the site of antigen exposure. In the case of the Mantoux test, the appearance of a papule 48 hours later indicates a delayed hypersensitivity reaction mediated by T cells. Choice B: Reaction of Arthus phenomenon type is incorrect as this type of reaction involves immune complexes forming in the blood vessels leading to tissue damage, which is not the mechanism seen in the Mantoux test reaction. Choice C: Reaction of serum sickness type is incorrect as this type of reaction involves the formation of immune complexes in the blood leading to systemic symptoms like fever, rash, and joint pain, which is not typically seen in the Mantoux test reaction. Choice D: Atopic reaction is incorrect as atopic reactions involve IgE antibodies and mast cell degranulation, which are not the mechanisms