Antibiotic resistance
Microbiology · Public Health · Pharmacology
Say it: an-tee-by-OT-ik rih-ZIS-tuns
Antibiotic resistance is the ability of bacteria to survive and multiply despite an antibiotic that once killed them or stopped their growth.
Also: antimicrobial resistance, AMR, antibacterial resistance
Definition
What is antibiotic resistance?
Antibiotic resistance is when bacteria change so that a drug that used to kill them or stop their growth no longer works. It is the bacteria, not the patient's body, that become resistant. It is part of the wider problem of antimicrobial resistance, which also includes resistant fungi, viruses and parasites, and it ranks among the gravest threats to global public health.
Resistance arises through natural selection. A random mutation, or a gene picked up from another microbe, may let a bacterium survive a drug, and bacteria can share such genes on plasmids and other mobile DNA, even across species. Every time an antibiotic is used, susceptible cells die and resistant ones are left to multiply, so overuse and misuse in people and in animals speed the process. Resistant bacteria may keep the drug out, pump it back out, break it down with enzymes such as beta-lactamases, change the drug's target, or bypass the step the drug blocks.
Resistant infections, such as those caused by MRSA or carbapenem-resistant Gram-negative bacteria, are harder to treat, may require more toxic second-line drugs, and sometimes have no effective treatment left. Worldwide, drug-resistant bacterial infections are linked to millions of deaths each year.
Word parts
Where does the term “antibiotic resistance” come from?
- anti-
- againstGreek anti
- bio-
- lifeGreek bios
- resist-
- to stand againstLatin resistere, from re- + sistere, to stand
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- AntibioticAn antibiotic is a drug that kills bacteria or stops them from growing, used to treat or prevent bacterial infections; it has no effect on viruses.
- Natural selectionNatural selection is the process by which inherited traits that improve survival and reproduction become more common in a population over generations.
- PlasmidA plasmid is a small, usually circular DNA molecule that copies itself independently of the main chromosome, found mostly in bacteria.
- MutationA mutation is a lasting change in an organism's DNA sequence, ranging from a single altered base to large rearrangements of chromosomes.
- BacteriumA bacterium is a single-celled prokaryote with no nucleus, found in almost every habitat on Earth, including in and on the human body.
- Gram-negative bacteriaGram-negative bacteria have a thin peptidoglycan wall wrapped in an outer membrane, so they lose the purple dye in a Gram stain and look pink.
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