Which of the following concerning nosocomial infections is incorrect?

Correct Answer: B

Rationale: The correct answer is B because Helicobacter pylori is not typically associated with nosocomial infections. Nosocomial infections are usually caused by bacteria commonly found in healthcare settings, such as Clostridium difficile, which is mentioned in choice D. Choices A, C, and D are correct as nosocomial infections can be caused by both Gram-negative and Gram-positive bacteria, often antibiotic-resistant species, and commensal flora bacteria like Clostridium difficile.

Correct Answer: B

Rationale: The correct answer is B because the statement is false. Memory B cells are formed during an immune response and persist long-term, allowing for a faster and more robust response upon reinfection with the same antigen. The number of memory B cells recognizing an antigen is typically greater than the number of naïve B cells, as they are specifically primed and preserved. In contrast, naïve B cells are naive to the antigen and need to undergo activation and differentiation upon encountering the antigen for the first time. Therefore, statement B is incorrect as it inaccurately suggests that memory B cells are always fewer than naïve B cells recognizing the same antigen.

Correct Answer: C

Rationale: The correct answer is C because both external barriers (Skin, Secretions, Mucous membranes) and internal defenses (Inflammatory response) are types of innate immunity. External barriers physically block pathogens from entering the body, while internal defenses involve cellular and molecular responses to eliminate pathogens. Choice A alone does not cover internal defenses, and choice B alone does not cover external barriers, making them individually incomplete. Choice D is incorrect as innate immunity does involve specific barriers and responses. Therefore, choice C is the best answer as it encompasses both types of innate immunity barriers.

Correct Answer: D

Rationale: The correct answer is D because anemia is defined as having abnormally low amounts of hemoglobin or red blood cells, leading to reduced oxygen-carrying capacity. This results in symptoms such as fatigue and weakness. Choice A is incorrect because anemia is not related to cancer of white blood cells. Choice B is incorrect as anemia does not result in extra leukocytes; rather, it leads to a decrease in red blood cells. Choice C is incorrect as anemia is not usually fatal if treated promptly and effectively.

Correct Answer: B

Rationale: The correct answer is B: 40-60%. Hematocrit represents the percentage of red blood cells in the blood. The normal range for hematocrit in a healthy adult is typically around 40-60%. Values below 40% may indicate anemia, while values above 60% may suggest conditions like dehydration or polycythemia. Choices A, C, and D are incorrect because they fall outside the normal range for hematocrit levels in a healthy adult.