Introduction to Beta-lactam Antibiotics.pdf

An introduction to beta lactam antibiotics is discussed in these slides.

1. INTRODUCTION TO BETA-LACTAM
ANTIBIOTICS
Dr. Ajmer Singh Grewal

2. β-lactam antibiotics
β-lactam antibiotics (beta-lactam antibiotics) are antibiotics that contain a beta-lactam ring in their molecular
structure.

β-lactam ring

3. β-lactam antibiotics include penicillin derivatives (penams), cephalosporins (cephems), monobactams,
carbapenems and carbacephems.

Most β-lactam antibiotics work by inhibiting cell wall biosynthesis in the bacterial organism and are the most
widely used group of antibiotics.

Until 2003, when measured by sales, more than half of all commercially available antibiotics in use were β-
lactam compounds.

4. Penicillins

Penicillins: Penicillins are a group of antibiotics originally obtained from Penicillium moulds, principally P.
chrysogenum and P. rubens. The first β-lactam antibiotic discovered, penicillin, was isolated from a rare
variant of Penicillium notatum (since renamed Penicillium chrysogenum).

5. Cephalosporins

Cephalosporins: The cephalosporins are a class of β-lactam antibiotics originally derived from the fungus
Acremonium, which was previously known as “Cephalosporium”.

6. Monobactams

Monobactams: Monobactams are monocyclic and bacterially-produced β-lactam antibiotics. The β-lactam
ring is not fused to another ring, in contrast to most other β-lactams. Monobactams are effective only against
aerobic Gram-negative bacteria (e.g., Neisseria, Pseudomonas). Siderophore (high-affinity iron-chelating
compounds)-conjugated monobactams show promise for the treatment of multi drug-resistant pathogens.
Aztreonam is a commercially available monobactam antibiotic. Other examples of monobactams are
tigemonam, nocardicin A, and tabtoxin.

7. Aztreonam

8. Carbapenems
Carbapenems: Carbapenems are a class of highly effective antibiotic agents commonly used for the treatment
of severe or high-risk bacterial infections. This class of antibiotics is usually reserved for known or suspected
multidrug-resistant (MDR) bacterial infections.

9. Carbacephems: Carbacephems are a class of synthetic antibiotics, based on the structure of cephalosporin, a
cephem. Carbacephems are similar to cephems, but with a carbon substituted for the sulfur. For example,
Loracarbef.

Loracarbef

10. β-lactamase inhibitors

Bacteria often develop resistance to β-lactam antibiotics by synthesizing a β-lactamase, an enzyme that attacks
the β-lactam ring. To overcome this resistance, β-lactam antibiotics can be given with β-lactamase inhibitors
such as clavulanic acid, sulbactam, tazobactam.