-|A beta-lactam ring (β-lactam) or penam is a
lactamwith a heteroatomic ring structure, consisting of three carbonatoms and one nitrogen atom[Heterocyclic chemistry T.L. Gilchrist ISBN 0-582-01421-2 ] .
The beta-lactam ring is part of the structure of several
antibioticfamilies, principally the penicillins, cephalosporins, carbapenems and monobactams, which are therefore also called " beta-lactam antibiotics". These antibiotics work by inhibiting the bacterial cell wallsynthesis. This has a lethal effect on bacteria, especially on Gram-positiveones. Bacteria can become resistant against beta-lactam antibiotics by expressing beta-lactamase.
The first synthetic β-lactam ever was prepared by
Hermann Staudingerin 1907 by reaction of the Schiff baseof anilineand benzaldehydewith diphenylketene["Hugo (Ugo) Schiff, Schiff Bases, and a Century of b-Lactam Synthesis" Thomas T. Tidwell Angew. Chem. Int. Ed.2008, 47, 1016–1020 DOI|10.1002/anie.200702965 ] [H. Staudinger, Justus Liebigs Ann. Chem. 1907, 356, 51 – 123.] in a [2+2] cycloaddition::
Because of the popularity of beta-lactam drugs, certain bacteria have been able to develop counter-measures to traditional drug therapies. An enzyme called
beta-lactamaseis present in many different types of bacteria, which serves to 'break' the beta lactam ring, which effectively nullifies the antibiotic's effectiveness.
As a response to bacterial resistance to beta-lactam drugs, there are drugs, such as
Augmentin, which are designed to disable the beta-lactamase enzyme. Augmentinis made of amoxicillin, a beta-lactam antibiotic, and clavulanic acid, a beta-lactamase inhibitor. The clavulanic acid is designed to overwhelm all beta-lactamase enzymes, bind irreversibly to them, and effectively serve as an antagonist so that the amoxicillin is not affected by the beta-lactamase enzymes.
Secondary beta-lactam drug resistance
As a response to decreased efficacy of beta-lactamase, some bacteria have changed the proteins that beta-lactam antibiotics bind, the
penicillin binding proteins(PBPs). Since the PBPs no longer recognize the beta-lactams, the antibiotics are essentially useless. This is the mechanism behind the methicillin-resistant Staphylococcus aureus (MRSA).
ATC code J01#J01C Beta-lactam antibacterials.2C penicillins
* [http://www.organic-chemistry.org/synthesis/heterocycles/lactams/beta-lactams.shtm Synthesis of beta-lactams]
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