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 impor tance has been learned from the study of this bacterium and the diseases it causes. Streptococcus pneumoniae is associated with the development of Gra m's stain, the Quellung reaction, and many of the fundamentals of immunolog y. It has also played a significant role in the history of antimicrobial th erapy. After a transitory period of euphoria engendered by the improved pro gnosis of pneumococcal pneumonia resulting from therapeutic advances, recog nition that the newer treatments could not bring about the recovery of thos e sustaining early irreversible physiologic injury led to renewed interest in immunoprophylaxis. Added impetus to this approach has been fostered by t he recent rapid increase in the number of pneumococcal isolates resistant t o antimicrobial agents and in the magnitude of their resistance. Pneumococc al vaccines are increasingly relevant.