Drugs
Section: Biology | Syllabus: Cambridge IGCSE Combined Science (0653)
What is a Drug?
A drug is any substance taken into the body that modifies or affects chemical reactions in the body.
Antibiotics
- Antibiotics are used to treat bacterial infections (e.g. penicillin)
- Antibiotics kill bacteria, but do not affect viruses
Antibiotic Resistance
Some bacteria are resistant to antibiotics, which reduces the effectiveness of those antibiotics against them.
Limiting the Development of Resistant Bacteria (Supplement)
Using antibiotics only when essential can limit the development of resistant bacteria, such as MRSA (methicillin-resistant Staphylococcus aureus):
- Every time an antibiotic is used, any bacteria that happen to carry resistance are more likely to survive and reproduce, while non-resistant bacteria are killed
- Unnecessary use of antibiotics increases how often bacteria are exposed to them, giving resistant strains more opportunities to be selected for and spread
- Prescribing antibiotics only when essential reduces this selection pressure, slowing the spread of resistant bacteria such as MRSA
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