What is antibiotic-resistant Streptococcus pneumoniae?

In the 1940s, penicillin antibiotics became available and were used effectively to treat pneumococcal infections. During the 1960s, however, the first pneumococcal bacteria that were not susceptible ("resistant") to penicillin were discovered in humans. Since then, penicillin resistant pneumococcal bacteria have been reported all over the world. By the late 1970s, pneumococci that were resistant to other types of antibiotics in addition to penicillins were reported. These "multidrug resistant" pneumococci have now been reported all over the world.