Galen (AD 129-199) propounded the notion that all wounds healed by second intention and the concept of laudable pus became unshakeable for almost 15 centuries. But William of Saliceto (AD ca 1210-1280) held quite firmly that pus formation was bad for both wound and patient and proclaimed that wounds should heal by first intention. The first rational theory of the nature of infection was by Fracastoro (1478-1553), a physician of Verona who regarded infection as being due to the passage of minute bodies from one person to another. But it was not until the work of Pasteur (1822-1895) that bacteriology took a significant leap forward. The association between bacteria and infection was slow to be accepted. The work of Semmelweis (1818-1865) is notable for his association between bacterial infection and puerperal fever. Lister (1827-1912) began the modern movement to control infection with his pioneering work in antiseptic surgery. Other contributions came from von Bergman (1836-1907; steam sterilization of instruments) and Halstead (1852-1922; rubber gloves for surgeons). The aseptic system has changed very little since then except for the innovations of Sir John Charnley (1911-1982; the laminar flow enclosure). The development of safe antibacterial drugs has been confined to the 20th century. This was led by Domagk (1895-1964; sulfonamides) and was followed by Sir Alexander Fleming (1881-1955), Sir Howard Walter Florey (1898-1968) and Sir Ernest Boris Chain (1906-1979; penicillin) and Selman Waksman (1888-1973; actinomycin).