It is quite amazing that the oldest group of medically useful
antibiotics, the fJ-Iactams, are still providing basic microbiologists,
biochemists, and clinicians with surprises over 50 years after Fleming's
discovery of penicillin production by Penicillium. By the end of the
1950s, the future of the penicillins seemed doubtful as resistant
strains of Staphylococcus aureus began to increase in hospital
populations. However, the development of semisynthetic penicillins
provided new structures with resistance to penicillinase and with
broad-spectrum activity. In the 1960s, the discovery of cephalosporin C
production by Cephalosporium and its conversion to valuable
broad-spectrum antibiotics by semisynthetic means excited the world of
chemotherapy. In the early 1970s, the 40-year-old notion that fJ-Iactams
were produced only by fungi was destroyed by the discovery of cephamycin
production by Streptomyces. Again this basic discovery was exploited by
the deVelopment of the semisynthetic cefoxitin, which has even broader
activity than earlier fJ-Iactams. Later in the 1970s came the
discoveries of nocardicins from Nocardia, clavulanic acid from
Streptomyces, and the carbapenems from Streptomyces. Now in the 1980s we
learn that fJ-Iactams are produced even by unicellular bacteria and that
semisynthetic derivatives of these monobactams may find their way into
medicine. Indeed, the future of the prolific fJ-Iactam family seems
brighter with each passing decade.