Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance where the drugs are no longer effective. Fungi evolve antifungal resistance, viruses evolve antiviral resistance, protozoa evolve antiprotozoal resistance, and bacteria evolve antibiotic resistance. Together all of these come under the umbrella of antimicrobial resistance. Microbes resistant to multiple antimicrobials are called multidrug resistant (MDR) and are sometimes referred to as superbugs. Although antimicrobial resistance is a naturally occurring process, it is often the result of improper usage of the drugs and management of the infections.
Antibiotic resistance tests: Bacteria are streaked on dishes with white disks, each impregnated with a different antibiotic. Clear rings, such as those on the left, show that bacteria have not grown—indicating that these bacteria are not resistant. The bacteria on the right are fully resistant to three of seven and partially resistant to two of seven antibiotics tested.
A CDC infographic on how antibiotic resistance (a major type of antimicrobial resistance) happens and spreads
A CDC infographic on how antibiotic resistance spreads through farm animals
A number of mechanisms used by common antibiotics to deal with bacteria and ways by which bacteria become resistant to them
A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells.
A cluster of Escherichia coli bacteria magnified 10,000 times
Mahavira postulated the existence of microscopic creatures in the 6th century BC
Antonie van Leeuwenhoek was the first to study microscopic organisms.
Lazzaro Spallanzani showed that boiling a broth stopped it from decaying.
