The word antibiotic comes from the Greek anti meaning 'against' and bios meaning 'life' (a bacterium is a life form). Antibiotics are also known as antibacterials, and they are drugs used to treat infections caused by bacteria. Bacteria are tiny organisms that can sometimes cause illness to humans and animals.

Such illnesses as tuberculosis, salmonella, syphilis and some forms of meningitis are caused by bacteria. Some bacteria are not harmful, while others are good for us.

Before bacteria can multiply and cause symptoms our immune system can usually destroy them. We have special white blood cells that attack harmful bacteria. Even if symptoms do occur, our immune system can usually cope and fight off the infection. There are occasions, however, when it is all too much and our bodies need some help from antibiotics.

The first antibiotic was Penicillin. Such Penicillin related antibiotics as Ampicillin, Amoxicillin and Benzylpenicilllin are widely used today to treat a variety of infections. These antibiotics have been around for a long time.

Although there are a number of different types of antibiotic they all work in one of two ways:

  • A bactericidal antibiotic kills the bacteria. Penicillin is a bactericidal. A bactericidal usually either interferes with the formation of the bacterium's cell wall or its cell contents.
  • A bacteriostatic stops bacteria from multiplying.

An antibiotic is given for the treatment of an infection caused by bacteria. They target only bacteria - they do not attack other organisms, such as fungi or viruses. If you have an infection it is important to know whether it is caused by bacteria, and not a virus or fungus. Most upper respiratory tract infections, such as the common cold and sore throats are generally caused by viruses - antibiotics do not work against viruses.

If antibiotics are overused or used incorrectly there is a chance that the bacteria will become resistant - the antibiotic becomes less effective against that type of bacterium.

A broad-spectrum antibiotic can be used to treat a wide range of infections. A narrow-spectrum antibiotic is only effective against a few types of bacteria. There are antibiotics that attack aerobic bacteria, while others work against anaerobic bacteria. Aerobic bacteria need oxygen, while anaerobic bacteria do not.

Antibiotics may be given beforehand, to prevent infection, as might be the case before surgery. This is called 'prophylactic' use of antibiotics. They are commonly used before bowel and orthopedic surgery.