ANTIBIOTICS

These are chemicals which in low concentrations can selectively kill or inhibit the growth of most pathogenic micro organisms. Antbiotics are produced by micro organisms like Bacteria and fungi and are not harmful to humans . For example the antibiotics penicillin G is produced by the blue green mould penicillium. This chemical interferes with the synthesis of cell walls in Bacteria especially gram positive bacteria and neisseriae and prevent their growth . It has no effect on the cells of higher organisms . Antibiotics like chloramphenicol and tetracycline are effective against both gram positive and gram negative bacteria.
Generally antibiotics are used to control diseases caused by pathogenic bacteria. They are however not effective in controlling pathogenic viruses and protozoa.