Antibiotic
Microbiology · Pharmacology · Medicine
Say it: an-tee-by-OT-ik
An 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.
Also: antibiotics, antibacterial drug, antibacterial
Definition
What is an antibiotic?
An antibiotic is a medicine that treats bacterial infections either by killing bacteria (a bactericidal effect) or by halting their growth (a bacteriostatic effect) so the immune system can clear them. The first antibiotics were natural substances made by one microorganism that harm others: penicillin comes from the mold Penicillium, and soil bacteria of the genus Streptomyces are the source of many more. The term now also covers semisynthetic drugs, which are chemically modified natural compounds, and fully synthetic ones.
Antibiotics rely on selective toxicity: they strike structures or processes that bacteria have and human cells lack or build differently. Penicillins and other beta-lactams block construction of the peptidoglycan cell wall. Tetracyclines, aminoglycosides and macrolides jam the bacterial 70S ribosome. Fluoroquinolones block an enzyme that untangles DNA, and sulfonamides cut off the making of folic acid. Narrow-spectrum drugs act on a few kinds of bacteria; broad-spectrum drugs act on many, but also disturb more of the helpful microbiome.
Alexander Fleming noticed penicillin's effect in 1928, and it came into wide use in the 1940s. Antibiotics do not work against viruses, so they do not help colds or flu, and overuse speeds the rise of antibiotic resistance.
Word parts
Where does the word “antibiotic” come from?
- anti-
- againstGreek anti
- bio-
- lifeGreek bios
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Terms that go with it
- Antibiotic resistanceAntibiotic resistance is the ability of bacteria to survive and multiply despite an antibiotic that once killed them or stopped their growth.
- BacteriumA bacterium is a single-celled prokaryote with no nucleus, found in almost every habitat on Earth, including in and on the human body.
- PeptidoglycanPeptidoglycan is the mesh-like polymer of sugars and short peptides that forms the bacterial cell wall and gives bacteria their shape and strength.
- RibosomeA ribosome is a molecular machine of RNA and protein that reads messenger RNA and joins amino acids in the order it specifies to build a protein.
- MicrobiomeA microbiome is the community of bacteria, fungi, viruses and other microbes, with their genes, that lives in a particular place, such as the human gut.
- Gram stainThe Gram stain is a lab staining method that sorts bacteria into Gram-positive (purple) and Gram-negative (pink) groups based on their cell walls.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- OpenStax Microbiology, 14.1 History of Chemotherapy and Antimicrobial Discovery
- OpenStax Microbiology, 14.3 Mechanisms of Antibacterial Drugs
- MedlinePlus: Antibiotics
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