Tetracyclines are a class of related antibiotic compounds first discovered by retired American botanist Benjamin Duggar (1) in the late 1940s. Duggar extracted a yellowish crystalline compound with unique antibacterial properties, called aureomycin (7-chlortetracycline), from soil found near cemeteries containing Streptomyces aureofaciens, a fungallike bacteria of the Actinomycetales order. The parent compound, tetracycline, was subsequently produced by the removal of the chlorine atom from aureomycin by catalytic hydrogenation (2). Tetracycline and its semisynthetic derivatives are active against a wide variety of Gram-positive and Gram-negative bacteria, chlamydiae, mycoplasmas, rickettsiae, and protozoan parasites. Although tetracyclines have been used commercially only since the 1950s, earlier civilizations might have unknowingly benefited from their antibiotic properties. Bone samples from 1600-yr-old Nubian (northern Sudanese) mummies have shown evidence of intermittent tetracycline incorporation, apparently from Streptomycetes contamination of grains used to make bread and beer (7). More than 50 different antibiotics have been isolated from Streptomycetes species, including streptomycin, neomycin, chloramphenicol, and tetracyclines.