Antibiotics and Painkillers
Laura Armstrong & Joe Wolfensohn
Teachers
Contents
Recall Questions
This topic requires prior knowledge of how pathogens cause disease, and the differences between bacteria and viruses.
How do bacteria make us ill?
They produce toxins which damage our cells
How do viruses make us ill?
They invade host cells to reproduce and destroy the cell
How do white blood cells help fight infection?
They engulf pathogens or produce antibodies to destroy them
Topic Explainer Video
Check out this @JoeDoesBiology video that explains antibiotics and painkillers, then read the study notes. Once you’ve gone through them, don’t forget to try the practice questions!
Antibiotics and Painkillers
What Are Antibiotics?
- Antibiotics are medicines that kill bacteria or stop them reproducing.
- They do not work on viruses, because viruses live inside host cells, making them harder to target without damaging body cells.
- Penicillin was the first widely used antibiotic, discovered by Alexander Fleming. This antibiotic came from the penicillium mould.
The Importance of antibiotics
- Antibiotics have greatly reduced deaths from bacterial diseases (e.g., pneumonia, tuberculosis).
- Prevent complications: Antibiotics stop infections from becoming life-threatening.
- Enable other treatments: They are essential during surgeries or for cancer patients with weak immune systems.
Issues with antibiotics
- Misuse (e.g., not finishing a course or using them for viral infections) has led to antibiotic resistance, where the antibiotic is no longer effective at killing the bacteria.
- Resistant strains like MRSA are very hard to treat as this bacteria has evolved to develop resistance to many antibiotics.
- There is more about antibiotic resistance in a future study note - Resistant bacteria and MRSA in module 6.
What Are Painkillers?
- Painkillers (e.g., paracetamol, ibuprofen) relieve symptoms like pain or fever.
- They do not kill pathogens.
- They help patients feel better by reducing their symptoms while the immune system's white blood cells work to destroy the pathogens.
Key Terms
- Antibiotic – A drug that kills bacteria.
- Painkiller – A drug that reduces symptoms like pain.
- Antibiotic resistance – When bacteria mutate and are no longer killed by the antibiotic.
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Exam Tips
- DO NOT say antibiotics kill viruses – this is a common mistake, they only kill bacteria.
- DO NOT say bacteria become ‘immune’ to antibiotics. They become resistant.
- Remember painkillers do not kill the pathogen, they only reduce the symptoms.
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Practice Question
Explain why antibiotics cannot be used to treat measles infections. (3 marks)
Model Answer (Bullet Points):
- Measles is caused by a virus.
- Viruses live and reproduce inside host cells so the antibiotic cannot reach them (without damaging the host cell).
- Antibiotics only kill bacteria, not viruses.
More Practice
Try to answer the practice question from the TikTok video on your own, then watch the video to see how well you did!