In 1928, the Scottish physician and microbiologist Alexander Fleming made a landmark discovery at St Mary's Hospital in London that would fundamentally alter the course of modern medicine. Upon returning to his laboratory, he observed that a petri dish containing Staphylococcus bacteria had been contaminated by a mould, later identified as Penicillium notatum. Crucially, Fleming noticed that the bacteria surrounding the mould had been destroyed, revealing the potent antibacterial properties of the substance it produced.

Although Fleming identified the potential of this mould-derived substance, which he named penicillin, he faced significant challenges in isolating and stabilising it for clinical use. His initial findings provided the essential foundation for what would eventually become the world's first true antibiotic. This discovery marked the beginning of a new era in healthcare, shifting the medical paradigm from merely managing symptoms to effectively curing previously fatal bacterial infections.

The subsequent development of penicillin into a practical, mass-produced medicine required years of further research and collaboration. This transition transformed the treatment of infectious diseases, saving countless lives during the 20th century and beyond. The legacy of this breakthrough remains a cornerstone of public health, representing one of the most significant scientific achievements in the history of medicine.

• Alexander Fleming identifies the antibacterial properties of Penicillium mould.
• The discovery marks the dawn of the antibiotic era.
• Penicillin provides a revolutionary treatment for bacterial infections.
• The breakthrough fundamentally changes global public health outcomes.