The pneumococcus at the millennium: not down, not out.

In the 12 decades that will have elapsed between the first isolation of the pneumococcus and the coming millennium, much of fundamental biologic importance has been learned from the study of this bacterium and the diseases it causes. Streptococcus pneumoniae is associated with the development of Gram's stain, the Quellung reaction, and many of the fundamentals of immunology. It has also played a significant role in the history of antimicrobial therapy. After a transitory period of euphoria engendered by the improved prognosis of pneumococcal pneumonia resulting from therapeutic advances, recognition that the newer treatments could not bring about the recovery of those sustaining early irreversible physiologic injury led to renewed interest in immunoprophylaxis. Added impetus to this approach has been fostered by the recent rapid increase in the number of pneumococcal isolates resistant to antimicrobial agents and in the magnitude of their resistance. Pneumococcal vaccines are increasingly relevant.