Meningitis due to Streptococcus pneumoniae, a disease predominantly found in adults. In the U.S., about 20% of affected patients die. Because of the worldwide emergence of streptococcal resistance to penicillins, chloramphenicol, and cephalosporins, vancomycin, rifampin, and other antibacterial agents are used to treat this infection. Intravenous steroids (e.g., dexamethasone) given at the beginning of therapy decrease the risk of death and disability caused by this infection.