Answer to Question 1
Correct Answer: 2
Rationale 1: Invasiveness is not related to the production of endotoxins.
Rationale 2: Invasiveness is the term for the ability of a pathogen to grow rapidly.
Rationale 3: Virulence is the measure of an organism's pathogenicity.
Rationale 4: Invasiveness is not related to the ability of certain pathogens to penetrate anatomic barriers.
Global Rationale: Invasiveness is the ability of a pathogen to grow extremely rapidly and cause direct damage to surrounding tissues by their sheer numbers. Because a week or more may be needed to mount an immune response against the organism, this exponential growth can rapidly overwhelm body defenses and disrupt normal cellular function.
Answer to Question 2
Correct Answer: 2
Rationale 1: Another enzyme, coagulase, is secreted by S. aureus and protects it from phagocytes.
Rationale 2: Certain bacteria secrete hyaluronidase, which digests the matrix between human cells and allows the bacteria to penetrate anatomic barriers more easily.
Rationale 3: Hyaluronidase does not affect cell multiplication.
Rationale 4: Hyaluronidase is not involved in the production of exotoxins.
Global Rationale: Some streptococci, staphylococci, and clostridia secrete hyaluronidase, an enzyme that digests the matrix between human cells, allowing the bacteria to penetrate anatomic barriers more easily. Staphylococcus aureus secretes the enzyme coagulase, causing fibrin to be deposited on its cells, thereby protecting it from phagocytes.
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