Natural or synthetic substances which have a killing (bactericidal) or inhibiting (bacteriostatic) effect on pathogenic micro-organisms, usually bacteria. Antibiotics attack the microbes e.g. at the cell wall (penicillins, cephalosporins), the cell membrane permeability (polymyxins), the nucleus and protein synthesis (tetracyclines, gyrase inhibitors, pleuromutilins, oxazolidinone, chloramphenicol, aminoglycosides, lincosamides, macrolides, glycylclines). Cyclic lipopeptides penetrate the bacterial cytoplasmic membrane via lipid side chains and form pores (ion channels) in the presence of calcium, which lead to cytolysis of the pathogens (see also daptomycin).
Some antibiotics are also used as cytostatics, sometimes also as immunosuppressants, because of their inhibition of nucleic acid and protein synthesis (e.g. Adria-, Dauno-, Mito-, Actinomycin).
Topical antibiotics are mostly used for the treatment of wounds or for eradication in case of colonization with MRSA/ORSA (e.g. mupirocin).
Further details on antibiotics see below. Antibiotics/Internal Medicine