Editing Penicillin (section)

== Types ==
Penicillins consist of a distinct 4-membered [[beta-lactam]] ring, in addition to a thiazolide ring and an R side chain. The main distinguishing feature between variants within this family is the ''R substituent''. 

This side chain is connected to the 6-aminopenicillanic acid residue and results in ''variations'' in the antimicrobial spectrum, stability, and susceptibility to [[beta-lactamase]]s of each type.
=== Natural penicillins ===
Penicillin G (benzylpenicillin) was first produced from a [[penicillium]] fungus that occurs in nature. The strain of fungus used today for the manufacture of penicillin G was created by [[genetic engineering]] to improve the yield in the manufacturing process. None of the other natural penicillins (F, K, N, X, O, U1 or U6) are currently in clinical use.

===Semi-synthetic penicillin===
{{missing information|section|why – need to take stuff from the PV article History section on how it magically makes more|date=December 2022}}
Penicillin V (phenoxymethylpenicillin) is produced by adding the [[Precursor (chemistry)|precursor]] phenoxyacetic acid to the medium in which a genetically modified strain{{dubious|reason=Discovered before GMO, in 1946–48. Maybe split into a follow up sentence that says GM is done to optimize production?|date=December 2022}} of the [[penicillium]] fungus is being cultured.

=== Antibiotics created from 6-APA ===
There are three major groups of other [[semisynthesis|semi-synthetic]] [[antibiotic]]s related to the penicillins. They are synthesised by adding various side-chains to the [[Precursor (chemistry)|precursor]] [[6-APA]], which is isolated from penicillin G. These are the antistaphylococcal antibiotics, broad-spectrum antibiotics, and antipseudomonal antibiotics.

====Antistaphylococcal antibiotics====
* [[Cloxacillin]] (by mouth or by injection)
* [[Dicloxacillin]] (by mouth or by injection)
* [[Flucloxacillin]] (by mouth or by injection)
* [[Methicillin]] (injection only)
* [[Nafcillin]] (injection only)
* [[Oxacillin]] (by mouth or by injection)
Antistaphylococcal antibiotics are so-called because they are resistant to being broken down by staphylococcal [[Beta-lactamase|penicillinase]]. They are also, therefore, referred to as being penicillinase-resistant.

====Broad-spectrum antibiotics====
This group of antibiotics is called "broad-spectrum" because they are active against a wide range of Gram-negative bacteria such as ''[[Escherichia coli]]'' and ''[[Salmonella typhi]]'', for which penicillin is not suitable. However, resistance in these organisms is now common.
* [[Ampicillin]]
* [[Amoxicillin]]

There are many ampicillin precursors in existence. These are inactive compounds that are broken down in the gut to release ampicillin. None of these pro-drugs of ampicillin are in current use:
* [[Pivampicillin]] (pivaloyloxymethyl ester of ampicillin)
* [[Bacampicillin]]
* [[Metampicillin]] (formaldehyde ester of ampicillin)
* [[Talampicillin]]
* [[Hetacillin]] (ampicillin conjugated to acetone)

[[Epicillin]] is an aminopenicillin that has never seen widespread clinical use.

====Antipseudomonal antibiotics====
The Gram-negative species, ''[[Pseudomonas aeruginosa]],'' is naturally resistant to many antibiotic classes. There were many efforts in the 1960s and 1970s to develop antibiotics that are active against ''Pseudomonas'' species. There are two chemical classes within the group: carboxypenicillins and ureidopenicillins. All are given by injection: none can be given by mouth.

===== Carboxypenicillins =====
* [[Carbenicillin]]
* [[Ticarcillin]]
* [[Temocillin]]

===== Ureidopenicillins =====
* [[Mezlocillin]]
* [[Piperacillin]]
* [[Azlocillin]]

=== β-lactamase inhibitors ===
* [[Clavulanic acid]]
* [[Sulbactam]]
* [[Tazobactam]]