Beta-lactam antibiotics will be examined in four groups, including penicllins, cephalosporins, monobactams, and carbapenems. All of these contain a four-membered beta-lactam ring, which is necessary for exhibiting antibacterial activity. The beta-lactam ring is joined to a five-membered thiazolidine ring in penicillin, and a six-membered dihy-drothiazine ring in cephalosporins. In carbapenems, the beta-lactam ring is also joined to a five-membered ring, although it is carbocyclic. Monobactams have a monocyclic beta-lactam structure, and the side sulfo-group is joined to a nitrogen atom.
The primary mechanism of the action of beta-lactam antibiotics is the inhibition of synthesis of cell membranes of bacteria, which causes them to quickly die. Their initial action is to initiate the work of autolytic enzymes, which destroy cell membranes and cause lysis of the bacteria.
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