| Antibiotic | How it works |
| Penicillin | Breaks down cell walls |
| Erythromycin | Stops protein synthesis |
| Neomycin | Stops protein synthesis |
| Vancomycin | Stops protein synthesis |
| Ciprofloxacin | Stops DNA replication |
Antibiotics are substances that kill bacteria or stop their growth. They do not work against viruses: it is difficult to develop drugs that kill viruses without also damaging the body’s tissues.
To the right are some common antibiotics, with descriptions of how they work.
Penicillin
 |
|
A bacterium damaged
and distorted by penicillin |
The first antibiotic - penicillin - was discovered in 1928 by Alexander Fleming. He noticed that some bacteria he had left in a petri dish had been killed by naturally occurring penicillium mould.
Since the discovery of penicillin, many other antibiotics have been discovered or developed. Most antibiotics used in medicine have been altered chemically to make them more effective and safer for humans.
How bacteria develop resistance to antibiotics
Bacterial strains can develop resistance to antibiotics. This happens because of natural selection. In a large population of bacteria, there may be some cells that are not affected by the antibiotic. These cells survive and reproduce, producing even more bacteria that are not affected by the antibiotic.
MRSA (which stands for Methicillin-Resistant Staphylococcus Aureus) is very dangerous strain of bacterium, because it is resistant to most antibiotics. It is important to avoid over-use of antibiotics, so we can slow down, or stop, the development of other strains of resistant bacteria.
Cleanliness
One simple way to reduce the risk of infection is to
maintain personal hygiene and to keep hospitals clean. In the 19th century,
ideas about the importance of cleanliness in hospitals were ignored people
did not know that diseases were caused by pathogens that could be killed
with the approprate cleaning agents.
[ This page has been adapted from www.bbc.co.uk/schools/gcsebitesize/science
]