BRAINCAKEBroad-spectrum, Narrow spectrum, Bacteriostatic and Bactericidal
Antibiotics can be described in two separate ways: by the range of bacteria they act on, and by what they do to the bacteria.
Range
• A broad-spectrum antibiotic is effective against many types of bacteria, both Gram-positive and Gram-negative. Tetracyclines are an example. They are useful when the cause of an infection is not yet known.
• A narrow-spectrum antibiotic is effective against only a few types of bacteria. Penicillin G, for example, acts mainly on Gram-positive bacteria. It is used when the pathogen has been identified.
Narrow-spectrum antibiotics are often preferred, because broad-spectrum ones also kill many of the harmless bacteria of the gut. This can allow harmful species such as Clostridium difficile to multiply, and it exposes more species to the antibiotic, increasing selection for resistance.
Sign in free to see the rest of this lesson, the R.E.C.I.P.E. recall steps and the quiz
BrainCake is free. Make an account in seconds and pick up where this page stops.
Key terms in this lesson
- clostridium difficile
- A Gram-positive, spore-forming anaerobic bacterium that can overgrow in the gut after antibiotic use and cause colitis.
More in Bacteria and Disease
- Staphylococcus spp.
- Host Tissue Invasion
- Mycobacterium tuberculosis
- Antibiotics
- Antimetabolites
- Protein synthesis Inhibitors
- Cell Wall Agents
- Cell Membrane Agents
All 30 lessons in Bacteria and Disease · All Edexcel A-level Biology topics