It was on the golf course that Barry Rud first noticed something was seriously wrong. A trim 60-year-old who played hockey as a young man, he found himself unable to take more than a few steps without gasping for breath. His doctors said he had caught a strain of Pseudomonas aeruginosa, one of the growing number of “superbugs” that have evolved resistance to many common antibiotics.

Mr Rud’s experience illustrates a growing problem—and one possible solution to it. Antibiotics are among medicine’s most spectacular achievements. A class of “silver bullet” drugs that destroy disease-causing bacteria while sparing the patient’s own cells, they have defanged all sorts of once-feared illnesses, from cholera to syphilis. They have drastically reduced the risks of surgery (patients often died from infections caught on the surgeon’s table) and chemotherapy, which destroys the patient’s immune system.

But their magic is waning. Repeated exposure to a lethal threat has led bacteria to evolve resistance to many existing antibiotics, blunting their efficacy. At the same time, much of the pharmaceutical industry has lost interest in finding new ones. It has been almost 40 years since a new class of antibiotics has been made available to patients. Some infections, including gonorrhoea and tuberculosis, are once again becoming difficult to treat. One estimate, published in the Lancet in 2022, reckons antibiotic resistance directly caused 1.2m deaths in 2019, and was indirectly implicated in 3.8m more.

With antibiotics unable to cure his illness, Mr Rud took a chance. He travelled to the Eliava Institute in Tbilisi, Georgia, one of a handful of institutions specialising in the study of bacteriophages. These are viruses that infect and kill bacteria. The Eliava Institute uses them as living antibiotics, hoping to cure a human’s disease by causing one in the bacteria making him sick.

“Phages” are little known outside the former countries of the Soviet Union, which did the most to develop the idea. In Georgia they have been part of the local pharmacopoeia for decades. (Indeed, 2023 marks the Eliava’s centenary.) Little vials containing stale-tasting liquid full of anti-bacterial viruses can be bought at pharmacies across Tbilisi. Now, as worries about antibiotic resistance build, Western firms are taking a second look.