History of antibiotics: Who first discovered and reported the antibacterial substance “penicillin”?

Introduction / Context:
Penicillin marks the beginning of the modern antibiotic era. Distinguishing the discoverer from those who developed large-scale production is a classic exam point bridging microbiology and medical history.

Given Data / Assumptions:

• We are asked who first discovered and described penicillin's antibacterial effect.
• Discovery is distinct from clinical development and mass production.

Concept / Approach:
In 1928, Alexander Fleming observed that a contaminating mold (Penicillium notatum) on a Staphylococcus culture plate inhibited bacterial growth, and he named the substance “penicillin.” Years later, Howard Florey, Ernst Chain, and colleagues developed methods for purification and mass production, enabling clinical use during World War II.

Step-by-Step Solution:
Identify the original observer and namer: Alexander Fleming. Differentiate contributors: Florey and Chain (development/production), not discoverers in the strict sense; Paul Ehrlich pioneered Salvarsan (arsphenamine) for syphilis. Select Fleming as the correct answer.

Verification / Alternative check:
Historical accounts and Nobel recognitions align: the 1945 Nobel Prize in Physiology or Medicine was awarded jointly to Fleming, Florey, and Chain—recognizing discovery and development roles.

Why Other Options Are Wrong:
Lister advanced antisepsis (phenol), Ehrlich coined “magic bullet” and created Salvarsan; Florey was a developer, not the initial discoverer.

Common Pitfalls:
Confusing discovery with large-scale therapeutic deployment; examiners often test this nuance.

Final Answer:
Alexander Fleming.