Antimicrobial resistance

Antimicrobial resistance (AMR or AR) occurs when microbes evolve mechanisms that protect them from antimicrobials, which are drugs used to treat infections. This resistance affects all classes of microbes, including bacteria (antibiotic resistance), viruses (antiviral resistance), parasites (antiparasitic resistance), and fungi (antifungal resistance). Together, these adaptations fall under the AMR umbrella, posing significant challenges to healthcare worldwide. Misuse and improper management of antimicrobials are primary drivers of this resistance, though it can also occur naturally through genetic mutations and the spread of resistant genes.

Antibiotic resistance, a significant AMR subset, enables bacteria to survive antibiotic treatment, complicating infection management and treatment options. Resistance arises through spontaneous mutation, horizontal gene transfer, and increased selective pressure from antibiotic overuse, both in medicine and agriculture, which accelerates resistance development.

The burden of AMR is immense, with nearly 5 million annual deaths associated with resistant infections. Infections from AMR microbes are more challenging to treat and often require costly alternative therapies that may have more severe side effects. Preventive measures, such as using narrow-spectrum antibiotics and improving hygiene practices, aim to reduce the spread of resistance. Microbes resistant to multiple drugs are termed multidrug-resistant (MDR) and are sometimes called superbugs.

The World Health Organization (WHO) claims that AMR is one of the top global public health and development threats, estimating that bacterial AMR was directly responsible for 1.27 million global deaths in 2019 and contributed to 4.95 million deaths. Moreover, the WHO and other international bodies warn that AMR could lead to up to 10 million deaths annually by 2050 unless actions are taken. Global initiatives, such as calls for international AMR treaties, emphasize coordinated efforts to limit misuse, fund research, and provide access to necessary antimicrobials in developing nations. However, the COVID-19 pandemic redirected resources and scientific attention away from AMR, intensifying the challenge.

Antimicrobial resistance means that a microorganism is resistant to an antimicrobial drug that was once able to treat an infection by that microorganism. A person cannot become resistant to antibiotics. Resistance is a property of the microbe, not a person or other organism infected by a microbe. All types of microbes can develop drug resistance. Thus, there are antibiotic, antifungal, antiviral and antiparasitic resistance.

Antibiotic resistance is a subset of antimicrobial resistance. This more specific resistance is linked to bacteria and thus broken down into two further subsets, microbiological and clinical. Microbiological resistance is the most common and occurs from genes, mutated or inherited, that allow the bacteria to resist the mechanism to kill the microbe associated with certain antibiotics. Clinical resistance is shown through the failure of many therapeutic techniques where the bacteria that are normally susceptible to a treatment become resistant after surviving the outcome of the treatment. In both cases of acquired resistance, the bacteria can pass the genetic catalyst for resistance through horizontal gene transfer: conjugation, transduction, or transformation. This allows the resistance to spread across the same species of pathogen or even similar bacterial pathogens.

WHO report released April 2014 stated, "this serious threat is no longer a prediction for the future, it is happening right now in every region of the world and has the potential to affect anyone, of any age, in any country. Antibiotic resistance—when bacteria change so antibiotics no longer work in people who need them to treat infections—is now a major threat to public health."

Each year, nearly 5 million deaths are associated with AMR globally. In 2019, global deaths attributable to AMR numbered 1.27 million in 2019. That same year, AMR may have contributed to 5 million deaths and one in five people who died due to AMR were children under five years old.