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Antibiotics are among the most important medical discoveries in history, but their effectiveness is being threatened by the rise of antimicrobial resistance (AMR). This lesson covers the mechanisms of antibiotic action, how resistance develops and spreads, and strategies to combat AMR, as required by the Edexcel A-Level Biology (9BI0) specification.
Antibiotics are chemicals produced by microorganisms (or synthesised artificially) that kill or inhibit the growth of bacteria without significantly harming human cells.
| Term | Definition |
|---|---|
| Bactericidal | An antibiotic that kills bacteria |
| Bacteriostatic | An antibiotic that inhibits the growth of bacteria (stops them reproducing) without killing them |
| Broad-spectrum | Effective against a wide range of bacteria (both Gram-positive and Gram-negative) |
| Narrow-spectrum | Effective against only a specific group of bacteria |
Exam Tip: Antibiotics are effective against bacteria only. They do not work against viruses (which lack the cellular structures that antibiotics target). This is a very commonly examined point.
Antibiotics target specific bacterial structures or processes that are either absent from or significantly different in human cells.
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