Ever wondered how antibiotics work to combat harmful bacteria?
Before answering this question, it’s worth spending a little time looking at some of the basic structures of bacteria, as well as how they divide.
Bacteria are fairly simple single-celled organisms. They consist of:
- A cell wall (some bacteria don’t have cell walls, but the majority do. The detailed structure of the cell wall varies between bacteria).
- A cell membrane.
- DNA in the form of a circular chromosome. This contains all the bacterium’s genetic information.
- Cytoplasm, in which various components can be found, including ribosomes (where proteins are made), proteins and enzymes.
When bacteria divide, they first synthesise the new structural components of the cell wall and membrane, and the DNA replicates. Once this occurs, the cell splits in two, with each new cell containing a complete copy of the “parent’s” DNA.
Antibiotics interfere with certain aspects of bacterial cell growth or replication. Different types of antibiotic are effective against different parts of the bacterium. Generally speaking, there are three areas of the bacterium that are targeted by antibiotics:
- Cell wall synthesis.
- Protein synthesis.
- DNA synthesis or replication.
By either killing the bacteria, or reducing their ability to multiply, the antibiotics give the body’s own immune system a fighting chance against the organisms. Unfortunately, even with the best antibiotics, the infection may be so severe, or the immune system so weak, that bacteria are able to carry on multiplying and the person may die.
Bacteria are commonly divided into two groups – Gram positive and Gram negative. This has nothing to do with weight; it actually refers to the structure of the cell wall, which causes Gram positive organisms to appear purple, while Gram negative organisms appear pink when using a particular staining technique. This technique is Gram’s stain (named after the scientist Gram).