Disease And Immunity: Antibiotics

12.2 Antibiotics

Key Definition

• Drug: Any substance taken into the body that modifies or affects chemical reactions in the body.
• Antibiotics: Drugs used to treat bacterial infections.

How Antibiotics Work

• Kill bacteria or stop them multiplying.
• Do not affect viruses (viruses live inside host cells → protected).
• Example: Penicillin (first widely used antibiotic).

Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course

Antibiotic Resistance

• Some bacteria mutate → resistant to antibiotics.
• Resistant bacteria survive and reproduce.
• Example: MRSA (Methicillin-resistant Staphylococcus aureus).

Minimising Resistance

• Only use antibiotics when essential.
• Complete full course prescribed.
• Do not use leftover antibiotics.
• Control overuse in farming (animals given antibiotics unnecessarily).

Key Points To Remember

• Antibiotics effective against bacteria only, not viruses.
• Misuse accelerates resistance.
• Resistant strains = major global health problem.

Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course