A 36-year-old woman comes to the physician because of a 4-day history of fever, malaise, chills, and a productive cough. She has no prior medical conditions but experienced an influenza-like illness during the previous week. Her temperature is 38.8°C (101.8°F), pulse is 92/min, respirations are 23/min, and blood pressure is 128/74 mm Hg. On physical examination, the patient is ill-appearing and lethargic. There are crackles over the right lower lung. Leukocyte count is 20,000 cells/mm³. Chest imaging reveals extensive parenchymal consolidation and cavitations suggestive of abscesses in the right middle and lower lobes. The patient is endotracheally intubated for mechanical ventilation due to worsening respiratory failure. Culture of the tracheal aspirate grows gram-positive cocci in clusters. Which of the following bacterial virulence factors most likely contributed to this patient's necrotizing infection?

Question

Quizplus · Accepted Answer

Eductional Objective: Staphylococcus aureus strains that express Panton-Valentine leukocidin (PVL), a protease that kills leukocytes and causes necrosis, are most likely to cause skin or soft-tissue abscess and invasive disease (eg, necrotizing pneumonia).  PVL expression is most common in community-acquired, methicillin-resistant strains.

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