A 10-year-old boy suffers head trauma and lies unconscious for 2 weeks. He is now intubated. His temperature rises to 38.7degC (103degF) and oxygenation becomes more difficult. A chest X-ray reveals a pleural effusion and multiple abscesses in the lung parenchyma. Which of the following microorganisms is the most likely cause of this pulmonary infection?

Staphylococcal pneumonia is an uncommon community-acquired disease. However, pulmonary infection with Staphylococcus aureus is common as a superinfection after influenza and other viral respiratory tract infections. Nosocomial (hospital acquired) staphylococcal pneumonia typically occurs in chronically ill patients who are prone to aspiration or who are intubated. High incidence of complications, such as lung abscess and empyema. L. pneumophila, seen paicularly in individuals with co-morbid conditions (e.g., hea or lung disease) and in organ transplant recipients.