Antibiotics and limiting resistance

Last time

Before we start: last time, in The eye, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.

A miracle that is wearing out

Before antibiotics, a scratch that became infected could kill you. Penicillin, found in 1928, changed medicine. But bacteria are fighting back, by becoming resistant. Today: what antibiotics do, what they cannot do, and how to slow resistance.

Drugs

A drug is any substance taken into the body that modifies or affects chemical reactions in the body. Antibiotics are drugs that kill bacteria, or stop them growing. They are used to treat bacterial infections, such as cholera and some pneumonias.

How antibiotics work

Antibiotics target structures and processes found in bacteria but not in human cells. For example, some damage the bacterial cell wall, which human cells do not have. So they harm the bacteria without harming the patient's cells.

Why not viruses?

Antibiotics do not work against viruses. Viruses are not cells: they have no cell wall and no metabolism of their own for the drug to attack. They reproduce inside our own cells, so flu, colds and H I V are not treated with antibiotics.

Antibiotic resistance

In a population of bacteria, random mutations mean a few may be resistant to an antibiotic. When the antibiotic is used, the non-resistant bacteria die, but the resistant ones survive. The survivors reproduce and pass on the resistance gene. Soon most of the population is resistant. This is natural selection.

MRSA

M R S A is a strain of bacteria resistant to many antibiotics. It is hard to treat, and spreads in hospitals. This is why reducing resistance matters for everyone.

Limiting resistance

Three ways to slow down resistance. Use antibiotics only for bacterial infections, never for viruses. Complete the full course, even when you feel better. And use them less often, including less use in farm animals.

Why finish the course?

If you stop early, the most resistant bacteria may still be alive. They can multiply and spread, and the infection may return. Finishing the course gives the best chance of killing all of them.