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β-Lactam antibiotics are indicated for the prevention and treatment of bacterial infections caused by susceptible organisms. At first, β-lactam antibiotics were mainly active only against gram-positive bacteria, yet the recent development of broad-spectrum β-lactam antibiotics active against various gram-negative organisms has increased their usefulness.
The β-lactam core structures. (A) A penam.(B) A carbapenam.(C) An oxapenam.(D) A penem.(E) A carbapenem.(F) A monobactam.(G) A cephem.(H) A carbacephem.(I) An oxacephem. This is a list of common β-lactam antibiotics—both administered drugs and those not in clinical use—organized by structural class.
The reactive site is a beta-lactam nucleus, while the main peripheral functional groups are a quaternary quinolinium, an aminothiazolyl moiety and an unusual O-alkylated oxime. Cefquinome acts by inhibition of the cell wall synthesis, but it has a relatively short half-life of about 2.5 hours.
A lactam is a cyclic amide, and beta-lactams are named so because the nitrogen atom is attached to the β-carbon atom relative to the carbonyl. The simplest β-lactam possible is 2-azetidinone. β-lactams are significant structural units of medicines as manifested in many β-lactam antibiotics. [2]
The contraindication, however, should be viewed in the light of recent epidemiological work suggesting, for many second-generation (or later) cephalosporins, the cross-reactivity rate with penicillin is much lower, having no significantly increased risk of reactivity over the first generation based on the studies examined.
Cross-reactivity, in a general sense, is the reactivity of an observed agent which initiates reactions outside the main reaction expected. This has implications for any kind of test or assay , including diagnostic tests in medicine, and can be a cause of false positives .
In general, treatment with cephalosporins results in induction of AmpC beta-lactamase. [2] Treatment with an aminoglycoside or carbapenem is usually indicated. Carbapenems are a class of beta-lactam antibiotics with a broad spectrum of antibacterial activity. They have a structure that renders them highly resistant to beta-lactamases.
The β-lactam ring is not fused to another ring, in contrast to most other β-lactams. [1] Monobactams are narrow-spectrum antibiotics [2] effective only against (strictly or facultatively [3]) aerobic Gram-negative bacilli, [4] [5] [3] exhibiting a high level of resistance to beta-lactamases of these organisms. [3]