Academic Reading — Test 176

Reading passage

When the first antibiotics entered widespread use in the middle of the twentieth century, they were greeted as a decisive victory over infectious disease. Illnesses that had once killed routinely became treatable within days, and the confidence of the medical profession grew accordingly. Yet that optimism overlooked a fundamental feature of biology: bacteria evolve. Every time a population of microbes is exposed to a drug, a few individuals may carry chance mutations that allow them to survive. These survivors reproduce, passing on their resistance, while the vulnerable strains are eliminated. Over successive generations, the proportion of resistant bacteria rises, and a medicine that once worked reliably begins to fail. This process, though entirely predictable, was for decades treated as a distant concern rather than an immediate threat. The pace at which resistance has spread owes much to human behaviour. In many countries, antibiotics have been prescribed for ailments against which they have no effect, such as common viral infections. Patients have frequently stopped taking their medication once symptoms eased, leaving behind the hardiest bacteria to multiply. Perhaps more significantly, vast quantities of antibiotics are used in agriculture, where they are added to animal feed not only to treat illness but also to promote faster growth. This continuous, low-level exposure across enormous animal populations creates ideal conditions for resistant strains to emerge and to pass into the wider environment through water and soil. Resistance, in short, is not confined to hospitals; it is woven into the global food and water systems on which everyone depends. The consequences are already visible. Certain strains of tuberculosis no longer respond to the standard combination of drugs, requiring longer, more toxic and far more expensive treatment. Infections acquired during routine surgery, once easily controlled, can now prove stubborn or even fatal. Public health bodies warn that if current trends continue, procedures that modern medicine takes for granted, from hip replacements to chemotherapy, could become dangerously risky. The economic burden is considerable too, as resistant infections lengthen hospital stays and demand costlier care. Some analysts argue that the cumulative cost to the world economy over the coming decades could run into trillions, although such long-range figures are necessarily uncertain. Against this backdrop, the search for new drugs has taken on fresh urgency, yet it faces a stubborn obstacle. Developing a novel antibiotic is enormously expensive and time-consuming, and the commercial rewards are modest. A new antibiotic, unlike a drug for a chronic condition taken daily for years, is ideally used sparingly and only when older medicines fail. This deliberate restraint, sensible from a medical standpoint, makes the product unprofitable, and as a result many large pharmaceutical companies have withdrawn from the field altogether. The pipeline of new compounds has consequently thinned at precisely the moment when it is most needed. Several governments and charities have begun offering financial incentives to revive research, but progress remains slow. Scientists are nonetheless pursuing a range of promising avenues. One approach revisits the natural world, screening soil microbes and marine organisms for compounds that have never been catalogued. Advances in genetic sequencing now allow researchers to identify potential drugs hidden within organisms that cannot easily be grown in a laboratory. Another strategy turns to bacteriophages, viruses that infect and destroy bacteria with great precision, leaving the body's beneficial microbes untouched. Phage therapy, long neglected in much of the world, is attracting renewed interest as conventional drugs falter. Researchers are also exploring ways to disable the defensive mechanisms bacteria use to resist existing antibiotics, effectively restoring the potency of medicines already on the shelf. Few experts believe that any single breakthrough will end the threat, however. Because bacteria will eventually adapt to whatever is deployed against them, the challenge is better understood as a permanent contest rather than a problem to be solved once. Most specialists therefore stress that new drugs must be accompanied by careful stewardship: prescribing antibiotics only when genuinely necessary, improving hygiene and vaccination to prevent infections arising in the first place, and curbing their unnecessary use in farming. International cooperation is essential, since resistant bacteria respect no borders and travel readily with people, animals and goods. The struggle against resistance, in other words, is less a race with a finishing line than an ongoing effort to stay one step ahead.