Reading passage
In 1928, Alexander Fleming returned from holiday to his cluttered London laboratory and noticed that a mould contaminating one of his petri dishes had killed the surrounding colonies of staphylococcus bacteria. The mould was Penicillium, and Fleming, though unable to turn his observation into a usable drug, published his findings and moved on. It took another decade before Howard Florey, Ernst Chain and their Oxford team purified penicillin and showed, in 1941, that it could rescue patients dying of infections that had previously been untreatable. Mass production followed during the Second World War, and the antibiotic age had begun.
The decades that followed were astonishingly productive. Streptomycin, tetracycline, erythromycin and dozens of other compounds were discovered or synthesised, mostly by pharmaceutical companies screening soil samples for microbes that naturally produced antibacterial chemicals. Tuberculosis, once a leading cause of death in industrialised nations, became curable; routine surgery and childbirth, formerly shadowed by the threat of fatal infection, grew dramatically safer. By the 1960s, many physicians believed infectious disease had been permanently defeated. The US Surgeon General reportedly declared in 1969 that it was time to close the book on infectious diseases.
The optimism was misplaced. Bacteria reproduce so quickly that random mutations arise constantly, and any mutation that helps a bacterium survive an antibiotic will spread as its competitors die. This is natural selection operating in real time. Worse, bacteria can share resistance genes directly, passing packets of DNA called plasmids even between unrelated species. A resistance mechanism that evolves in one hospital can therefore appear, months later, in organisms on another continent. Antibiotics, uniquely among medicines, become less effective the more they are used.
Overuse has been rampant. In many countries antibiotics are sold without prescription and taken for viral illnesses such as colds and influenza, against which they are useless. Agriculture consumes enormous quantities: at one point, an estimated seventy percent of the antibiotics sold in the United States were given to farm animals, often at low doses to promote growth rather than cure disease. Such constant low-level exposure is an ideal recipe for breeding resistant strains, which can reach humans through food, water or direct contact.
Hospitals have also become engines of resistance. Crowded wards, invasive devices such as catheters, and heavy antibiotic use create ideal conditions for resistant organisms like MRSA, a staphylococcus that shrugged off methicillin within two years of the drug's introduction in 1960. In response, many hospitals now run stewardship programmes that audit prescriptions, restrict the most powerful drugs and test patients for resistant bacteria on admission. Simple measures matter too: rigorous handwashing, once controversial when the Hungarian doctor Ignaz Semmelweis proposed it in the 1840s, remains among the cheapest and most effective defences against the spread of infection.
The consequences are now measurable. The World Health Organization classifies antimicrobial resistance as one of the top ten global public health threats. A landmark review commissioned by the British government estimated that drug-resistant infections already caused at least 700,000 deaths a year worldwide and warned that, without action, the figure could reach ten million annually by 2050, exceeding the projected toll of cancer. Economists put the potential cost at around 100 trillion dollars in lost output over the same period.
The pipeline of new drugs offers little comfort. Developing an antibiotic costs hundreds of millions of dollars, yet any genuinely novel drug must be held in reserve and used sparingly, precisely to delay resistance. That makes antibiotics a poor investment compared with medicines taken daily for chronic conditions. Many large pharmaceutical firms have abandoned the field; between 2017 and 2021 only a handful of genuinely new antibiotic classes reached the market. Governments are experimenting with solutions, including subscription-style contracts in which companies are paid a fixed annual fee for access to new drugs regardless of how little they are used.
Meanwhile, older weapons are being rediscovered. Bacteriophages - viruses that infect and destroy bacteria - were used medically in Georgia and Poland throughout the twentieth century and are now attracting renewed Western interest, particularly for infections that no antibiotic will touch. Researchers are also mining genomes and even soil from unusual environments for compounds that bacteria have never encountered. Whether such efforts arrive in time is uncertain, but the lesson of the past century is clear: antibiotics are a finite resource, and medicine can no longer afford to treat them as an inexhaustible one.