Why Antibiotics Lose Power

Written by Studio AM.

An antibiotic can change which bacteria survive. Some bacteria carry genes that protect them from a particular drug. When that drug kills or slows susceptible bacteria, resistant ones may survive and multiply. This is selection: the population changes because some cells cope better with the conditions.

Resistance genes can arise through mutations or arrive from other bacteria. They do not appear because a cell decides it needs protection. Some are present before treatment; new genetic changes and gene transfers can also occur as populations continue growing.

Two features can help resistance spread. Some bacteria reproduce rapidly under favourable conditions, passing resistance genes to their descendants. Bacteria can also transfer genetic material between cells. For example, a small DNA loop called a plasmid may carry a resistance gene into another bacterium, sometimes of a different species.

Antibiotic use therefore creates selection pressure. Unnecessary treatment can favour resistant bacteria without helping the illness being treated. Antibiotics, for example, do not treat the viruses that cause colds. This does not make antibiotics useless: they remain important treatments for bacterial infections. Using them appropriately helps preserve that benefit.

Questions

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  1. Question 1 of 4

    Which statement best captures the passage's central claim?

  2. Question 2 of 4

    How can a resistance gene reach bacteria of a different species?

  3. Question 3 of 4

    Why can an unnecessary antibiotic for a cold cause problems?

  4. Question 4 of 4

    What does 'pressure' mean in the discussion of antibiotic resistance?

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