3.1.8: Antibiotics and painkillers
Not started yet — this one needs some love.
Antibiotics (e.g. penicillin): kill bacteria inside the body; do NOT affect viruses.
Specific antibiotics work against specific bacteria — use the correct one for the bacterial strain.
Antibiotic resistance in bacteria:
some bacteria develop resistance through random mutation
natural selection favours those that survive the antibiotic → resistant strains multiply
a major public health concern
Antibiotics cannot kill viruses, and antiviral drugs are hard to develop — viruses reproduce inside host cells, so a drug that kills the virus risks damaging the host cell too.
Painkillers (e.g. aspirin, paracetamol): relieve symptoms (pain, fever); do NOT kill pathogens or treat the infection.
Common exam mistakes
Antibiotics kill bacteria only — they have NO effect on viruses; this is a fundamental exam point.
BACTERIAL resistance, NOT antibiotic resistance — bacteria develop resistance (mutations), not the antibiotic. Do NOT say 'antibiotic is resistant' or 'bacteria become immune to the antibiotic'.
Penicillin is an antibiotic — it is NOT a painkiller; do not confuse these.
Antibiotic resistance: the antibiotic does not cause mutations — mutations occur randomly in bacteria; antibiotics simply select for bacteria that already have a resistance mutation, allowing them to survive and multiply.
Painkillers treat symptoms (e.g. fever, pain), NOT the infection itself; they do not kill pathogens.
Viruses are hard to treat because they live inside host cells — any drug that kills viruses risks damaging the host's own cells.
Saying 'bacteria become immune to the antibiotic' is WRONG — immunity refers to the immune system's response, not to bacteria. Say 'bacteria become resistant to the antibiotic' instead.