Discovery of Penicillin

Fleming's Accidental Discovery

• Date & Location: London, 1928
• Event: Mold spores drift onto a petri dish in Alexander Fleming's lab.
• Fleming's Role: Scottish scientist investigating infectious bacteria.
• Observation: Mold colony with a surrounding zone clear of bacteria after returning from vacation.

Identification and Naming

• Realization: Mold secretes a compound killing bacteria.
• Mold Genus: Penicillium.
• Compound Named: Penicillin.

Mechanism of Action

• Defense System: Mold produces penicillin to defend against bacterial colonies.
• Action on Bacteria:
  • Disrupts synthesis of bacterial cell walls.
  • Binds to compounds in the cell wall mesh, preventing reconstruction.
  • Stimulates release of reactive molecules causing further damage.
  • Result: Breakdown of bacterial cell structure.
• Safety: Not harmful to human cells as they lack cell walls.

Development and Use

• Early Stage: Laboratory curiosity for a decade.
• WWII Impact: Researchers isolate active compound and grow mold in larger quantities.
• Recognition: Nobel Prize awarded for this work.
• Commercialization: Available within a few years, developed by teams at Oxford and American drug companies.
• Medical Impact: Transformed infection treatment, remains a crucial antibiotic.

Challenges

• Antibiotic Resistance:
  • Bacteria evolve resistance with increased use.
  • Some bacteria produce compounds breaking down penicillin’s key structure.
  • Rising ineffective cases against bacterial infections.
• Prescribing Practices: Essential to avoid overprescribing.

Penicillin Allergy

• Prevalence: 5-15% of patients in developed countries self-report allergies.
• Misconception: Over 90% of these people are not actually allergic.
• Common Cause of Mislabeling: Rash during childhood treatment often blamed on penicillin instead of infection or reaction between infection and antibiotic.
• Genuine Allergy: Rare but dangerous, immune system mistakes penicillin as an attacker.
• Testing: Allergist evaluation to confirm true allergy.
• Outgrowing Allergy: 80% outgrow within 10 years; potential for penicillin to be life-saving.

Summary

Penicillin's accidental discovery by Alexander Fleming led to a revolutionary antibiotic that transformed medical treatment for infections. Despite challenges like antibiotic resistance and misconceptions about allergies, penicillin remains a vital drug in healthcare.