A 72-year-old woman is brought to the emergency department with fever, myalgia, and cough for 3 days. She lives in an assisted living facility and several of her neighbors have had similar symptoms. She has hypertension treated with lisinopril. She has not been vaccinated against influenza. Her temperature is 38.9°C (102.2°F), pulse is 105/min, respirations are 22/min, and blood pressure is 112/62 mm Hg. On examination, there are crackles at the base of the left lung. Chest x-ray reveals a left lower-lobe consolidation. Microscopic analysis of a sputum sample shows gram-positive, lancet-shaped cocci in pairs. Which of the following characteristics are these bacteria likely to demonstrate?

Question

A 72-year-old woman is brought to the emergency department with fever, myalgia, and cough for 3 days. She lives in an assisted living facility and several of her neighbors have had similar symptoms. She has hypertension treated with lisinopril. She has not been vaccinated against influenza. Her temperature is 38.9°C (102.2°F), pulse is 105/min, respirations are 22/min, and blood pressure is 112/62 mm Hg. On examination, there are crackles at the base of the left lung.  Chest x-ray reveals a left lower-lobe consolidation.  Microscopic analysis of a sputum sample shows gram-positive, lancet-shaped cocci in pairs.  Which of the following characteristics are these bacteria likely to demonstrate?

Quizplus · Accepted Answer

Eductional Objective: Streptococcus pneumoniae are gram-positive, a-hemolytic, optochin-sensitive, bile-soluble diplococci.  Viridans group streptococci are also a-hemolytic, but they are optochin-resistant and bile insoluble.  Streptococcus pyogenes (Group A Streptococcus) appear as gram-positive cocci in chains with bacitracin susceptibility.

A 72-Year-Old Woman Is Brought to the Emergency Department with Fever