A 36-year-old woman comes to the physician because of a 4-day history of fever, malaise, chills, and a cough productive of moderate amounts of yellow-colored sputum. Over the past 2 days, she has also had right-sided chest pain that is exacerbated by deep inspiration. Six months ago, she was diagnosed with a urinary tract infection and was treated with oral trimethoprim/sulfamethoxazole. She appears pale. Her temperature is 38.8°C (101.8°F), pulse is 92/min, respirations are 20/min, and blood pressure is 128/74 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 99%. Examination shows pale conjunctivae. Crackles are heard at the right lung base. Chest x-ray reveals consolidation in the right upper lobe. Gram stain of the sputum shows numerous polymorphonuclear leukocytes and gram-positive cocci in pairs. When cultured on a blood agar plate under aerobic conditions, the bacterial colonies are surrounded by a zone of incomplete hemolysis. The organism responsible for this patient's condition is most likely to exhibit which of the following virulence features?

Question

A 36-year-old woman comes to the physician because of a 4-day history of fever, malaise, chills, and a cough productive of moderate amounts of yellow-colored sputum. Over the past 2 days, she has also had right-sided chest pain that is exacerbated by deep inspiration. Six months ago, she was diagnosed with a urinary tract infection and was treated with oral trimethoprim/sulfamethoxazole. She appears pale. Her temperature is 38.8°C (101.8°F), pulse is 92/min, respirations are 20/min, and blood pressure is 128/74 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 99%. Examination shows pale conjunctivae. Crackles are heard at the right lung base. Chest x-ray reveals consolidation in the right upper lobe.  Gram stain of the sputum shows numerous polymorphonuclear leukocytes and gram-positive cocci in pairs.  When cultured on a blood agar plate under aerobic conditions, the bacterial colonies are surrounded by a zone of incomplete hemolysis.  The organism responsible for this patient's condition is most likely to exhibit which of the following virulence features?

Quizplus · Accepted Answer

Eductional Objective: The primary virulence factor of Streptococcus pneumoniae is a polysaccharide capsule that inhibits opsonization and phagocytosis.  The polysaccharide capsule of the most virulent strains is targeted by the pneumococcal vaccine, which confers immunity against those subtypes.

A 36-Year-Old Woman Comes to the Physician Because of a 4-Day