Main Page | See live article | Alphabetical index Beta-lactam in a heteroatomic ring structure, consisting of three carbon atoms and one nitrogen atom (Fig. 1). The beta-lactam ring is part of several antibiotics, such as penicillin, which are therefore also called beta-lactam antibiotics. These antibiotics work by inhibiting the bacterial cell wall synthesis. This has a lethal effect on bacteria, especially on Gram-positive ones. Bacteria can become resistant against beta-lactam antibiotics by expressing beta-lactamase. Figure 1: Penicillin-G. Beta-lactam ring marked blue. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.