Penicillin

Penicillin works by attacking the cell walls of bacteria

Penicillin targets bacteria at their weakest point—their cell walls. By blocking wall-building, it leaves microbes unable to survive, causing them to burst and die.

Penicillin slashed battlefield pneumonia deaths during World War II

Before antibiotics, bacterial pneumonia killed about 18% of infected soldiers in World War I. By World War II, penicillin cut that death rate to less than 1%.

Penicillin was hailed as a 'wonder drug' upon its release

When penicillin became widely available in the 1940s, newspapers and doctors alike celebrated it as a “wonder drug” that could cure infections once considered fatal.

Penicillin has saved an estimated 500 million lives since its creation

Since its introduction in the 1940s, penicillin and related antibiotics are estimated to have saved around 500 million lives worldwide—making it one of the most consequential medical breakthroughs in human history.

Penicillin was discovered by accident

In 1928, Alexander Fleming returned from vacation to find mold contaminating a petri dish of bacteria. Around the mold, the microbes had died—an accidental observation that led to the discovery of penicillin.

The same mold behind penicillin also flavors blue cheese

There are over 300 species of Penicillium. The mold that produces the lifesaving antibiotic is a close relative to those used to make blue cheeses like Roquefort and Stilton and to flavor some types of ham.

Pneumonia was once a leading killer before penicillin treatments

In the early 20th century, pneumonia was a top cause of death worldwide, often fatal without effective treatment. Penicillin turned a once deadly infection into one of the most treatable bacterial diseases.

Penicillin ended scarlet fever’s deadly threat to children

Between 1840 and 1883, scarlet fever was among the leading causes of childhood death in the United States, with case fatality rates ranging from 15% to 30%. Today, thanks to antibiotics like penicillin, the mortality rate is below 1%.

Diphtheria was once a leading childhood killer before antibiotics and vaccines

In 18th- and 19th-century outbreaks, some New England families lost as many as eight children to diphtheria, and fatality rates in hospitals often topped 60%. The invention of antitoxins, penicillin, and vaccines dramatically reduced deaths.

Oxford scientists turned Fleming’s mold discovery into medicine

In 1939, a team at Oxford—including Howard Florey, Ernst Chain, and Norman Heatley—revived Fleming’s forgotten discovery. Using makeshift equipment like bedpans and milk churns, they purified enough penicillin to prove it could treat deadly infections.