Antibiotics are usually defined as chemicals of natural organic origin that will kill certain harmful pathogens. Antibiotics are usually produced by organisms living in the soil. Main producers of antibiotics include the molds Pennicillium and Cephalosporium and the bacterium Antinomycetes sptromyces. All of these organisms produce spores, and there is thought to be some connection between the processes of spore-production and antibiotic synthesis.
In order for an antibiotic to be useful, it must have certain properties. It should be able to destroy many different species of pathogens. It should not be toxic or have undesirable side effects to the host. In order for it to be practically used, it must be easy and inexpensive to produce. Also, resistance to it must remain uncommon.
Below is a list of useful antibiotics and information about each:
Cell wall synthesis inhibitors usually stop bacteria from forming their cell walls. They kill bacteria and not human cells because human cells do not form cell walls. Examples of cell wall synthesis inhibitors are beta lactums, semisynthetic penicillins, and bacitracin.
Cell membrane inhibitors kill bacterial cells by disorganizing the outer membranes of bacteria. An example of a cell membrane inhibitor is polymyxin.
Protein synthesis inhibitors intefere with the process of translation in protein synthesis. Their action is usually on the ribosomes. Examples of protein synthesis inhibitors are tetracyclines, chloramphenicol, macrolides, and aminoglycosides.
Chemotheraputic agents affecting the synthesis of nucleic acids block the division and growth of cells by inhibiting synthesis of DNA and RNA. Most of these agents affect both animal and bacteria cells, so they cannot be used as an antibiotic. However, nalidixic acid and rifamycins are selectively active towards bacteria.