Superbugs

Background

Superbugs are bacteria, fungi, viruses, or parasites that cause disease and have developed antimicrobial resistance—meaning they no longer respond to at least some of the medicines used to treat them. However, the term “superbug” is most commonly used to refer to bacteria that have become antibiotic-resistant.

Globally, it is estimated that superbugs killed almost 1.3 million people and contributed to the death of nearly 5 million people in 2019 alone.

Where Do Superbugs Come From?

There are many kinds of bacteria, and the human body is home to an estimated 39 trillion bacteria—more than the number of cells—of all types. The vast majority is harmless and even provides important functions, but some can cause infections responsible for ailments from strep throat and whooping cough to Salmonella and tetanus.

Alexander Fleming discovered penicillin—the first antibiotic—in 1928. By 1945, Fleming had found penicillin-resistant bacteria and warned that people would die from antibiotic-resistant infections if antibiotics were not used wisely.

Bacteria reproduce quickly and are constantly mutating. Sometimes, they may stumble upon a mutation that provides a defense against threats, including drugs (see the process).

Every time bacteria are exposed to an antibiotic, there is a chance some bacteria will survive and develop resistance to the drug. This is more likely if patients do not take antibiotics as prescribed, including overuse. Examples of overuse or misuse include prescribing antibiotics for diseases unrelated to bacteria and the widespread use of antibiotics in agriculture for purposes other than treating disease.

Even isolated instances of antibiotic resistance can spread rapidly because bacteria have many different mechanisms for sharing genetic material with each other. So, if one bacterium has developed resistance to an antibiotic, it is able to pass that resistance to many other bacteria—even if they’re different types of bacteria.

Types of Superbugs

One notable example is MRSA (methicillin-resistant Staphylococcus aureus). S. aureus—the cause of staph infection—is a typically harmless bacteria found on the skin or nose that may cause serious health problems if it gets into cuts or wounds.

MRSA is strains that have developed resistance to antibiotic treatments, with often deadly consequences. It is responsible for more deaths than any other superbug, killing more than 120,000 people globally each year. Other superbugs are also lethal, such as Carbapenem-resistant Acinetobacter baumannii, or CRAB, which has a mortality rate of 47% (see top 10). Many superbugs are referred to as gram-negative, meaning they are enclosed in a protective outer membrane that makes it harder for the immune system to attack them (see overview).

Unfortunately, the superbug problem is getting worse. A 2024 study suggested that antimicrobial resistance could lead to a 70% increase in deaths attributable to superbugs by 2050, with older adults being most affected.

Fighting Superbugs

The research community continues to work on developing new antibiotics and other antimicrobial medicines. Many nations have signed on to a United Nations initiative to address the threat of superbugs through a variety of approaches, including the prevention of infections, a more targeted use of antibiotics, and efforts to address antibiotic use in agriculture.

There are also things you can do to reduce your risk of contracting a superbug: wash your hands, get vaccinated, use antibiotics according to the prescription, keep your pets healthy, and prepare food safely.