openstax microbiology test bank

Correct Answer: C

Rationale: The correct answer is C: Erysipelas. Erysipelas is a type of acute infection caused by group A Streptococcus bacteria. This bacteria infects the upper dermis and superficial lymphatics, leading to a distinct raised, well-demarcated, erythematous skin lesion. The other choices are incorrect because: A Carbuncle is a deep skin infection involving hair follicles, B Impetigo is a superficial skin infection caused by Staphylococcus or Streptococcus bacteria, and D Acne is a chronic inflammatory skin condition not typically caused by group A Streptococcus.

Correct Answer: D

Rationale: The correct answer is D. Sepsis is a systemic response to infection resulting in organ dysfunction. A: Sepsis can be caused by bacterial infection, but it is not solely defined by the presence of bacteria in the blood. B: Bacteremia is the presence of bacteria in the blood, which can be a component of sepsis, but sepsis involves a broader systemic response beyond just bacteremia. C: Sepsis can lead to the release of toxins and organ failure, but sepsis itself is not defined solely by the massive proliferation of toxins. Therefore, the correct answer is D, as sepsis can involve the presence of bacteria, bacteremia, systemic manifestations, and organ failure.

Correct Answer: A

Rationale: Rationale: A: Incorrect - The complement system is not directly involved in the viral neutralization reaction. B: Correct - Specific antibodies neutralize viruses by blocking their ability to infect cells. C: Incorrect - Antibodies are titrated, but only one serum sample is required for neutralization testing. D: Incorrect - Viral neutralization is primarily used to measure antibody response, not to identify newly isolated viruses.

Correct Answer: A

Rationale: Step 1: Streptococcus mutans is known for its ability to produce lactic acid, which contributes to the demineralization of tooth enamel, leading to dental caries. Step 2: Streptococcus pneumoniae is a common respiratory pathogen and not directly associated with dental caries. Step 3: Bacillus cereus is a foodborne pathogen and not typically found in the oral cavity or associated with dental caries. Step 4: Clostridium tetani causes tetanus, a neurological condition, and is not involved in the formation of dental caries. Summary: Choice A is correct as Streptococcus mutans is specifically linked to dental caries due to its acidogenic and aciduric properties. Choices B, C, and D are incorrect as they are not associated with dental caries.

Correct Answer: A

Rationale: The correct answer is A because lipophilization is the process of removing water from cells under deep vacuum in a frozen state. Dehydration of the cell at a low temperature helps to preserve the cellular structure and components. Choice B is incorrect as hydration does the opposite of what lipophilization aims to achieve. Choice C is incorrect as lipophilization does not involve enriching cells with proteins. Choice D is incorrect as lipophilization does not involve removing protein content from cells.