that the substance had been produced by that mould and so called it penicillin (Alexander).
             So, by accident, the first antibiotic was discovered. Many scientists attempted to repeat Fleming's work, and to produce penicillin, with no luck. Until many years, later Ronald Hare Fleming's assistant solved the mystery. He discovered that in order for the Penicillium to grow best, the temperature needed to be 20 degrees Celsius (Alexander). Fleming's discovery was capable because the summer had been extraordinarily cool.
             In 1938, ten years after Fleming's discovery, three scientists came across Fleming's work and attempted to produce penicillin (Alexander). It was not until May of 1940 that they had produced enough penicillin to test. They injected eight mice with a lethal dose of streptococci. They then injected four of the mice with penicillin. The next day the mice that had been injected with penicillin survived, while the other four perished (Alexander).
             Finally, by 1943 a pharmaceutical company, Heatley, was able to mass-produce penicillin. The miracle drug was then used on injured soldiers in North African, and by June 1944, unlimited treatment was possible for the troops (Alexander).
             Meanwhile, in 1939, Rene Dubos isolated and purified an antibiotic from a bacterium in soil. When applied to superficial wounds the bacteria worked well. However, it was too toxic for ingestion. In 1944, Selman Abraham Waksman was able to isolate streptomycin from a soil microbe. Streptomycin was successful in treating tubercle bacillus (Antibiotics, gme).
             During this period in time, many antibiotics were discovered, which led scientists to the production of synthetic antibiotics. Synthetic antibiotics began production in the 1960s, and they are still currently available (Antibiotics, gme).
             There are seven main categories of antibiotics. They include the penicillins, cephalosporins, aminoglyosides, tetracyclines, macrolides, sulfonamides, an...