Contains the full lesson along with a supporting toolkit, including teachers’ notes.
History happened at a London university in 1928 when Alexander Fleming noticed that a culture of Staphylococcus bacteria had been contaminated by a Penicillium mould. Wherever there were mould particles, the bacterial colonies had died. Fleming speculated that the fungus was producing an antibacterial substance. The idea of using biological rather than chemical agents against bacteria was not new. Pasteur had noted that anthrax bacteria multiplied in urine but stopped developing when other bacteria were added. In Italy, Arnaldo Cantani had some success in displacing tubercle bacteria when he painted the throats of infected people with other bacterial strains.
A wonder drug
Fleming’s experience included treating war wounds, often ineffectively, with antiseptics. Previously, he had discovered that lysozyme enzyme (from nasal mucus and tears) killed some types of bacteria. His subsequent work on penicillium showed penicillin extracts to be non- toxic, effective against gram-positive bacteria but very hard to produce in quantity. It was another 10 years before Howard Florey and his team isolated an active substance, penicillin G. Working with different penicillium strains, they used beer-brewing technology to improve output. UV / X-ray irradiation was used to develop a mutant penicillium strain that was a relatively prolific producer of the drug. Early experiments on mice and humans showed it to be very effective in treating infections.