What causes antibiotic resistance?

Bacteria is becoming increasingly resistant to the antibiotics we use to treat illness.

Asked by: Eddie Friel, Hull

Antibiotic resistance is a good example of natural selection. Exposure to antibiotics increases selective pressure in bacterial populations, boosting the percentage of resistant bacteria, with new bacterial generations inheriting resistance genes. Bacteria can sometimes pass on resistance by sharing genetic material with each other. They can also become resistant following spontaneous changes to their genes. Some gene mutations allow bacteria to produce enzymes that inactivate antibiotics. Others change their outer structure so that antibiotics can’t gain access. Some bacteria even develop pumping mechanisms to expel antibiotics. Overuse and misuse of antibiotics has exacerbated the problem of antibiotic resistance.

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