[AS PER AMENDMENT 10/23/97: SUBSTUDY CPCRA 054: A subset of participants of CPCRA 048 have oropharyngeal swabs taken at baseline and 4 months after randomization. Antibiotic susceptibility tests are then performed on isolates of S. pneumoniae.] [AS PER AMENDMENT 9/3/99: Participants in protocol version 3.0 are followed for data collection purposes every 4 months for 18 months until January 31, 2001. Data collection includes CD4 cell counts, viral RNA measurements, macrolide susceptibility in MAC isolates, and antibiotic susceptibility of isolates from bacterial pneumonia episodes.]