<prompt> An 83-year-old man with Parkinson disease presents with low-grade fever and cough for several weeks. Lately, he has been experiencing more rigidity and difficulty with his walking. He is on a levodopacarbidopa combination for treatment for the past 5 years. On examination, his gait is shuffling and slow. He has a tremor in his left hand at rest, and there is cog-wheel rigidity of the forearm There are crackles in the left lower lung field. CXR reveals a lung abscess in the left lower lobe. Which of the following is the most likely bacteriologic diagnosis for the lung abscess?oropharyngeal floratuberculosisStaphylococcus aureusPseudomonas aeruginosa  <response>: Most lung abscesses and all anaerobic abscesses involve the normal flora of the oropharynx. Septic embolic usually contain S aureus. Factors that predispose to Gram-negative colonization of the oropharynx include hospitalization, debility, severe underlying diseases, alcoholism, diabetes, and advanced age. Impaired consciousness, neurologic disease, swallowing disorders, and nasogastric or endo-tracheal tubes all increase the likelihood of aspiration. 