When an antibiotic or antimicrobial has lost its ability to effectively control or kill a bacteria, fungi, or parasite, it is considered “resistant.” These microbes continue to multiply even in the presence of therapeutic levels of an antibiotic or antimicrobial medication. Microbes become resistant through a genetic mutation or by acquiring the resistance from another pathogen. Every time a person takes an antibiotic or antimicrobial, sensitive microbes (that antibiotics can still attack) are killed, but resistant microbes survive. The number of drug-resistant microbes can increase in the environment if an antibiotic is overused.
Deeper dive
First introduced to the public in 1944, antibiotics and antimicrobials are drugs that kill harmful bacteria, fungi and parasites. They have all but eliminated the threat of diseases that once killed millions including sepsis, tuberculosis, plague and cholera. But overuse of these drugs in people and livestock animal farming has resulted in the breeding of “superbugs,” microbes that are resistant to most or all existing antibiotics.
Microbes become resistant to antibiotics naturally. When an antimicrobial is used, a few resistant strains survive, and continue to multiply and spread. They are resistant due to a genetic mutation, or through acquired resistance from other microbes. Mutations, rare spontaneous changes in bacteria’s genetic material, enable bacteria to inactivate or close off from an antibiotic. Bacteria can also acquire resistance by “mating” with one another, transferring genetic material with antibiotic resistance. Bacteria can collect multiple resistance traits, making it resistant to many if not all antibiotics.
Until the early 1980’s, pharmaceutical companies invested in developing new antimicrobials to keep ahead of evolving resistance, but the scientific and economic challenges of developing new antibiotics have led to a steep drop in the availability of new types of drugs, even as superbugs have spread.
Food farming has contributed to antimicrobial resistance. In the 1950’s, American agriculture researchers Thomas Jukes and Robert Stokstad discovered that giving small doses of antibiotics to chickens could speed up their growth and prevent infection. Their observation profoundly changed animal food production. It enabled the rise of concentrated animal feeding operations, where farmers could inexpensively raise hundreds of animals — chickens, pigs, and cows — and keep them healthy, even in close confinement. With the rise of industrial farming, millions of people have been able to get access to cheap animal meat. Approximately 65 percent of the medically important antibiotics sold in the United States in 2019 went to food animals — animals humans will eat, according to the Center for Infectious Diseases Research and Policy.
The routine use of antibiotics has also exposed quintillions of bacterial pathogens to antibiotics, increasing the evolutionary pressure on bacteria to develop resistance. Antibiotic resistant bacteria can then pass from animals to people through direct contact, contaminated meat, or environmental pathways such as water runoff or airborne dust.
Since the 1970s, a growing number of public health advocates have warned that the practice of feeding antibiotics to otherwise healthy animals, will result in more humans contracting antibiotic resistant pathogens. To read more about the risks of using antibiotics in food farming, see this 2021 Pew report.
For more details and resources on writing about antimicrobial resistance, see these two AHCJ tip sheets – Antibiotic resistance: how to cover this ongoing health story beyond the COVID-19 pandemic and What reporters need to know about antibiotic resistance.