How do people get infected with diphtheria

Correct Answer: C

Rationale: The correct answer is C because diphtheria is primarily spread through respiratory droplets and physical contact with an infected person. The bacteria responsible for diphtheria is transmitted through coughing, sneezing, or sharing personal items. Swimming in contaminated water (A) does not spread diphtheria. Transmission (B) is a broad term and does not specifically address the mode of transmission for diphtheria. Contaminated food (D) is not a typical route of diphtheria transmission. Therefore, option C is the most accurate choice based on the known mode of transmission for diphtheria.

Correct Answer: C

Rationale: The correct answer is C because coagulase helps bacteria like Staphylococcus aureus to form clots, allowing them to evade the host immune response. This mechanism helps the bacteria to hide from the immune system and establish infection. A. Adhesion to surfaces is usually facilitated by other factors like adhesins. B. Breaking down red blood cells is not a function of coagulase. D. Antibiotic resistance is typically mediated by other mechanisms like efflux pumps or enzymatic inactivation, not coagulase.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae are all bacteria associated with causing bacterial meningitis. Neisseria meningitidis commonly causes meningococcal meningitis, Haemophilus influenzae can cause H. influenzae type b meningitis, and Streptococcus pneumoniae is a common cause of pneumococcal meningitis. Therefore, all three bacteria are known to be causative agents of bacterial meningitis. The other choices are incorrect as they do not encompass all the bacteria associated with causing bacterial meningitis.

Correct Answer: A

Rationale: The correct answer is A: Salmonella enterica. This is because Salmonella are Gram-negative rods that do not ferment lactose, which fits the description in the question. Additionally, Salmonella is a common cause of severe abdominal pain and diarrhea. Shigella dysenteriae is a Gram-negative rod that also causes severe diarrhea but it does not share the characteristic of not fermenting lactose. Escherichia coli is a Gram-negative rod that does ferment lactose. Proteus vulgaris is also a Gram-negative rod but it is not commonly associated with severe abdominal pain and diarrhea, making it an unlikely causative agent in this scenario.

Correct Answer: A

Rationale: The correct answer is A: Lipopolysaccharides. Lipopolysaccharides (LPS) are major components of the outer membrane of Gram-negative bacteria and are known to have endotoxic activity. LPS can trigger a strong immune response leading to inflammation and septic shock. Choice B, Lipoproteins of Braun, are not known to have endotoxic activity. Choice C, Protein A, is a surface protein found in Staphylococcus aureus and is not associated with endotoxic activity. Choice D, None, is incorrect as LPS is indeed a bacterial structure with endotoxic activity.