{{drugbox |
| image=Ampicillin structure.svg
| width=220
| IUPAC_name = 7-(2-amino-2-phenyl-acetyl)amino-3,3</br>-dimethyl-6-oxo-2-thia-5-azabicyclo</br>[3.2.0]heptane-4-carboxylic acid
| CAS_number = 69-53-4
| ATC_prefix=J01
| ATC_suffix= CA01
| PubChem= 6249
| DrugBank= APRD00320
| C=16 | H=19 | N=3 | O=4 | S=1
| molecular_weight = 349.406 [[Gram|g]]/[[Mole (unit)|mol]]
| bioavailability = 40% (oral)
| protein_bound = 15 to 25%
| metabolism = 12 to 50%
| elimination_half-life = approx 1 hour
| excretion = 75 to 85% [[renal]]
| pregnancy_category = A <small>([[Australia|Au]])</small>, B <small>([[United States|U.S.]])</small>
| legal_status =
| routes_of_administration = Oral, [[Intravenous therapy|intravenous]]
}}
'''Ampicillin''' is a [[beta-lactam antibiotic|beta-lactam]] [[antibiotic]] that has been used extensively to treat [[bacterium|bacterial]] [[infection]]s since 1961. It is considered part of the [[aminopenicillin]] family and is roughly equivalent to [[amoxicillin]] in terms of spectrum and level of activity.<ref name=AHFS>{{ cite book | title= AHFS DRUG INFORMATION® 2006 | publisher= American Society of Health-System Pharmacists | date= 2006 | edition= 2006 ed}} </ref> It can sometimes result in allergic reactions that range in severity from a [[rash]] (e.g. patients with [[mononucleosis]]) to potentially lethal [[anaphylaxis]].

==Mechanism of action==
Belonging to the [[penicillin]] group of beta-lactam antibiotics, ampicillin is able to penetrate [[Gram-positive]] and some [[Gram-negative]] bacteria. It differs from penicillin only by the presence of an [[amino]] group. The amino group helps the drug penetrate the outer membrane of gram-negative bacteria. Ampicillin acts as a competitive inhibitor of the enzyme transpeptidase. Transpeptidase is needed by bacteria to make their cell walls.<ref name=AHFS/> It inhibits the third and final stage of bacterial [[cell wall]] synthesis, which ultimately leads to cell [[lysis]].

==Indications==
Ampicillin is closely related to [[amoxicillin]], another type of penicillin, and both are used to treat [[urinary tract infections]], [[otitis media]], uncomplicated community-acquired [[pneumonia]], ''[[Haemophilus influenzae]]'', [[salmonellosis]] and ''[[Listeriosis|Listeria]]'' [[meningitis]]. It is used with [[flucloxacillin]] in the combination antibiotic [[co-fluampicil]] for [[Empirical|empiric]] treatment of [[cellulitis]]; providing cover against [[Group A streptococcal infection]] whilst the flucloxacillin acts against the ''[[Staphylococcus aureus]]'' bacterium. Of concern is the number of bacteria that become [[antibiotic resistance|resistant]] to Ampicillin necessitating combination therapy or use of other [[antibiotics]].

All [[Pseudomonas]] and most strains of [[Klebsiella]] and [[Aerobacter]] are considered resistant.<ref name=Mosby> {{ cite book | title=Mosby's Drug Consult 2006 | publisher= Mosby, Inc. | date= 2006 | edition= 16 ed}} </ref>

===Use in research===
Ampicillin is often used as a selective agent in [[molecular biology]] to confirm the uptake of [[gene]]s (e.g., of [[plasmid]]s) 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'' (TEM-1) gene, coding for [[beta-lactamase|β-lactamase]]). The treated bacteria are then grown on a medium containing ampicillin. Only the bacteria that successfully take up the desired genes become ampicillin resistant, and therefore contain the other desired gene as well.

==External links==
== References ==
<div class="references-small" ><references/></div>
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{{PenicillinAntiBiotics}}
[[Category:Beta-lactam antibiotics]]

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