An antibiotic is a drug that kills or slows the growth of bacteria. (Drugs that kill bacteria are referred to as bacteriocidal; those that slow the growth of bacteria are referred to as bacteriostatic.) Antibiotics are chemicals produced by microorganisms such as bacteria and fungi.
There are many different kinds of antibiotics, and they destroy bacteria in different ways. The antibiotics within a class generally have similar effectiveness and mechanisms of action and resistance and they tend to attack the same types of bacteria. Some antibiotics, referred to as broad-spectrum antibiotics, treat a wide range of infections. Others, called narrow-spectrum antibiotics, are effective against only a few types of bacteria. Although antibiotics are sometimes used in conventional animal feeds, some of the antibiotics discussed below can be used only under the supervision of a veterinarian.
Major classes of antibiotics include the following:
- Aminoglycosides (e.g., gentamycin, neomycin, spectinomycin, and streptomycin)
- Bambermycins (e.g., bambermycin, flavophospholipol)
- Penicillins (e.g., penicillin and amoxycillin)
- Cephalosporins (e.g., cefotaxime)
- Glycopeptides (e.g., vancomycin—not approved for animal use)
- Ionophores (e.g., monensin)
- Lincosamides (e.g., lincomycin)
- Macrolides (e.g., erythromycin, tylosin)
- Polypeptides (e.g., bacitracin)
- Quinolones (e.g., fluoroquinolones)
- Streptogramins (e.g., virginiamycin)
- Sulfonamides (e.g., sulfa drugs)
- Tetracyclines (e.g., chlortetracycline and oxytetracycline)
Antimicrobial resistance is becoming an increasingly serious threat. If not addressed, by 2050 it could kill millions of people, more than from cancer or road traffic accidents. Our researchers, made up of one of the largest groupings of microbiologists in the world, are doing all they can to tackle this global issue by understanding how antibiotics work and finding new ways to prevent and treat infections.