Ampicillin (D-(-)-6-(2-amino-2-phenylacetamido)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0] heptane-2-carboxylic acid) is an antibiotic derived from penicillin. It is similar to amoxicillin and is one of the most useful derivatives of penicillin for two reasons. First, ampicillin is effective against a wide range of bacteria, including both gram positive and gram negative types. Second, ampicillin is less likely to break down in the acidic conditions of the stomach. This means that ampicillin can be taken orally instead of by injection. Ampicillin, amoxicillin, and penicillin all kill bacterial cells by the same mechanism. These drugs have a structure similar to certain pentapeptides made by the bacteria. These peptides are normally incorporated into the cell wall, however when the antibiotics are present they are incorporated instead. This makes the cell wall very weak and ultimately ruptures the cell.
Ampicillin has two main uses:
- Medical: Ampicillin was approved for medical use by the FDA in the early 1960s. Today ampicillin is distributed under the brand names Omnipen, Polycillin, and Principen, however it is prescribed less often now because of the creation of newer and better antibiotics. The drug is generally given orally to treat minor bacterial infections such as sinus, respiratory, ear, and bladder infections. It can also be given intravenously for more serious infections such as meningitis. The drug is generally not taken with meals, as food reduces its absorption into the bloodstream. Side effects of ampicillin include gastrointestinal problems and potential allergic reactions such as rashes and anaphylaxis.
- Molecular Biology Research: Researchers often need a large amount of their DNA sequence of interest in order to study it. Large concentrations are normally obtained by placing the DNA into a circular plasmid that is available commercially. The plasmid is then placed in bacteria such as E. coli that divide and create a large amount of the plasmid DNA. However, the insertion process is not 100% successful and the bacteria that do contain the plasmid need to be isolated from those that do not. Most commercially available plasmids also contain a gene that makes bacteria resistant to certain antibiotics, especially ampicillin. Therefore, adding ampicillin to the bacteria ensures that only those that contain the plasmid will survive. This makes the process faster and yields larger amounts of the DNA.