Nokea
A patient with a productive cough and fever had a sputum smear revealing Gram-positive cocci in pairs with a capsule. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. This bacterium is the most likely causative agent based on the description of Gram-positive cocci in pairs with a capsule. S. pneumoniae is known for its characteristic morphology and the presence of a capsule, which helps in evading the immune system. It commonly causes pneumonia, especially in patients with a productive cough and fever.
Incorrect choices:
B: Klebsiella pneumoniae typically presents with a mucoid capsule and is associated with pneumonia in immunocompromised individuals.
C: Neisseria meningitidis is a Gram-negative diplococcus and is more commonly associated with meningitis and septicemia.
D: Staphylococcus aureus is a Gram-positive cocci, but it does not typically present in pairs with a capsule and is more commonly associated with skin and soft tissue infections.