A 38-year-old man with known HIV infection diagnosed 4 years prior to hospital admission presented with cough and clear sputum production of 10 weeks in duration. He received a 5-day course of levofloxacin with no significant improvement of his symptoms. Six weeks prior to hospital admission, he began to complain of fatigue and dyspnea on exertion. This became progressively worse over the last few days. He also noted to have a fever of 38.3°C. He has never been treated for HIV infection. He stopped smoking 2 years ago, after accumulating a 5-pack-year smoking history.