The discovery of antibiotics and their widespread availability revolutionised healthcare after the Second World War. They underpin many of the greatest medical advances of the 20th century. But bacteria and pathogens have always evolved to resist the new drugs that scientists invent to combat them. Resistance has increasingly become a problem in recent years because the pace at which we are discovering new antibiotics has slowed drastically, while antibiotic use, and therefore resistance, is rising.
“antimicrobial resistance is a crisis that must be managed with the utmost urgency. As the world enters the ambitious new era of sustainable development, we cannot allow hard-won gains for health to be eroded by the failure of our mainstay medicines.” - Dr Margaret Chan, Director General, World Health Organization
What is antimicrobial resistance?
Antimicrobial resistance is a natural process whereby microbes evolve to be able to resist the action of drugs, making them ineffective. Resistance arises from the selection pressure that antimicrobials put on populations of microbes; essentially selecting or allowing those microbes to survive and proliferate, typically through genetic changes. This leads to antibiotics becoming less effective over time and in many extreme cases, ultimately useless.
Why is it a problem?
Although AMR is a naturally occurring process, today it is a threat because of two main reasons. The first is that use of antimicrobials has increased so much in the last few decades that microbes are exposed to a much larger number and greater concentration of antimicrobials increasing their chances of developing resistance. The second is that, worryingly, in some categories of antimicrobials (particularly antibiotics) there are very limited numbers of new drugs under development to replace those rendered ineffective by rising drug resistance. Essentially, the demand for new drugs has increased due to increasing resistance but the supply has dried up leaving us in a precarious position.
The reasons for this problem are at least partly economic and commercial. In the case of antibiotics, the predominance of cheap generics means that prevailing prices are low; unpredictable patterns of emerging resistance make future medical needs (and thus commercial opportunities) hard to predict ; and conservation measures necessary to limit the prescribing of antibiotics would relegate new products to last-line treatments used only when nothing else works. This all leads to antibiotics being seen as commercially unattractive. Economic interventions are thus needed to stimulate investment whilst protecting drugs from unnecessary use.
The global burden of infections resistant to existing antimicrobial medicines is now growing at an alarming pace. Drug-resistant infections are already responsible for more than half a million deaths globally each year. Early research commissioned by the Review suggests that if the world fails to act to control resistance, this toll will exceed 10 million each year by 2050 and have cost the world over 100 trillion USD in lost output.
Resistance is not an isolated phenomenon though the extent of resistance varies across different countries and regions of the world. This variation is often linked to the extent of use in these countries or regions. For instance areas with greater use of antimicrobials are associated with greater levels of resistance. But increasing international travel means that AMR has the capability of spreading globally including to countries that are controlling their antibiotics use effectively. This makes a strong case for international coordination on AMR as no country can protect itself from resistant bacteria unless the world takes action together.
Added to these issues, are the overuse and unnecessary use of antimicrobials for humans and animals which also promote the development and spread of resistance, either directly or through the environment.
Much of the misuse of antimicrobials is associated with the lack of rapid diagnostics that can pin-point the exact nature of the diseases causing microbe. Doctors and prescribers, unsure of the kind of disease affecting their human or animal patient but still needing to provide treatment to them, rely on empirical or treatment with broad-spectrum drugs that may or may not cure the patient but still expose microbes to a variety of drugs increasing the likelihood of resistance developing of these drugs.
Figures suggest that much of the use of antibiotics in the world is for animals rather than humans and that much of this is for promoting the growth of animals rather than treating sick animals. The development and spread of drug resistance in the environment is also often overlooked. Antimicrobials can also reach the environment through waste products from the manufacturing sector that do not adequately treat the waste products and through use and excretion by humans and animals.
The overuse of antimicrobials is also related to high rates of infection and the dependence on antimicrobials as curative treatments, reducing the focus afforded to prudent measures that might prevent an infection in the first place.
AMR is an issue that spans multiple areas and cannot be solved by any one solution. Nor is it an issue that any one country can address successfully by acting alone. Hence a multi-disciplined approach to solving the diverse issues and coordination among various countries is critical.
“By highlighting the vast financial and human costs that unchecked drug resistance will have, this important research underlines that this is not just a medical problem, but an economic and social one too.”- Dr Jeremy Farrar, Director of the Wellcome Trust