A 40-year-old man with HIV comes to the physician for a 3-day history of worsening cough and fever. Temperature is 101 F. Physical examination shows dullness to percussion of the right lower lobe. Current medications are zidovudine, didanosine, ritonavir, and trimethoprim/sulfamethoxazole. Which of the following is the most likely diagnosis?
Atypical bacterial species
Gram-negative diplococcus
Gram-positive diplococcus
Virus
Yeast
