S ; CAS No.: 69-53-4) is an aminopenicillin and, as such, is a broad-spectrum antibiotic
and has been used extensively to treat bacterial
infections since 1961
. It is suspected to cause certain types of cancer
and animals. Belonging to the group of beta-lactam antibiotics, ampicillin is able to penetrate Gram-negative
bacteria. It inhibits the third and final stage of bacterial cell wall
synthesis, which ultimately leads to cell lysis
, so it belongs to a group of bactericidal antibiotics.
Ampicillin is often used in molecular biology as a test for the uptake of genes (e.g., by plasmids) by bacteria (e.g., E. coli). A gene that is to be inserted into a bacterium is coupled to a gene coding for an ampicillin resistance (in E. coli, usually the bla gene, coding for β-lactamase). The treated bacteria are then grown on a medium containing ampicillin. Only those bacteria that carry the ampicillin resistance and, therefore, the gene can survive.