Antibiotics are drugs used in human health care and in veterinary practice to treat bacterial infections. Since their discovery in the 1930s, antibiotics have made it possible to cure diseases such as pneumonia, tuberculosis and meningitis saving the lives of millions of people around the world.

Antibiotics attack a metabolic pathway present in the bacterium (prokaryotes) but not in the host (man and animals; eukaryotes). Antibiotics of natural origin can be produced by fungi or soil bacteria. E.g. penicillin is produced by the fungus Penicillium notatum. Today, penicillin is made from cultures of Penicillium chrysogenum that has been specially adapted for high yields. Natural antibiotics can be modified chemically resulting in semi-synthetic products. These products are more efficient than the natural product, have reduced side effects, develop less resistance by the targeted bacteria and / or expand the range of bacteria that can be treated. An example of complete synthetic antibiotics are the sulphonamides.

Especially in aqua culture and chicken industry the use of cheap antibiotics puts high pressure on human health and bacterial resistance. Antibiotics are divided into groups depending on their chemical structures and biological activity. The main groups are: amphenicols (chloramphenicol), aminoglycosides, sulphonamides, fluoroquinolones, macrolides, nitrofurans, tetracyclines and beta-lactams.