Science & Technology in Action

9th Edition

Penicillin: A Life Saving Antibiotic

Teva Ireland

The world of pharmaceuticals was changed forever when Alexander Fleming discovered penicillin in 1928. The TEVA lesson describes the background to this discovery and the subsequent impact of the antibiotic. Penicillin chemistry is discussed and its effect on inhibiting the development of pathogenic bacteria is described.

Contains the full lesson along with a supporting toolkit, including teachers’ notes.

Lesson excerpt

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.

Quiz questions

  1. Penicillins are the only antibiotics containing a beta-lactam ring. false
  2. Penicillins have been effectively used against fungi and other parasites as well as bacteria. false
  3. Antibiotics have been administered preventatively to people with compromised immune systems. true
  4. Penicillium generally produces penicillin under stress and not during normal active cell growth. true
  5. Bactericidal antibiotics do not actually kill the bacteria. true
  6. Bacteria have evolved that are resistant to methicillin, a synthetic penicillin. true
  7. Oxacillin, cloxacillin, amoxicillin and ampicillin are different types of penicillin. true
  8. Penicillins are stored in warm conditions in order to minimise hydrolysis of the beta-lactam ring. false
  9. Penicillin can induce a severe reaction if taken with alcohol. true

Glossary of terms

amino acid