Characterization of Streptococcus pneumoniae from human immunodeficiency virus--seropositive patients with acute and recurrent pneumonia.

Thirty-two isolates of clinically significant Streptococcus pneumoniae from 11 human immunodeficiency virus (HIV)-seropositive patients with single or multiple episodes of pneumonia were characterized by antibiotic susceptibility testing, serotyping, ribotyping, and repetitive extragenic palindromic polymerase chain reaction (REP-PCR). The isolates comprised 10 serotypes, 12 ribotyping patterns, and 12 REP-PCR patterns. There was close but not absolute correlation between techniques. By combining these characterization methods, 14 strains were identified. Five strains were found in > 1 patient, suggesting their frequent occurrence in this population. Two isolates of different serotype from 1 patient were highly related by ribotyping and REP-PCR, suggesting possible in vivo serotype change. Acute infection was associated with single strains or coinfection by distinct strains. Recurrent pneumonia was identified as relapse with the same strain or reinfection with new strains. The molecular characterization of pneumonococci from HIV-seropositive persons refines our understanding of pneumonococcal infection in these patients.