beta lactamases are enzymes synthesised by some bacteria to degrade beta-lactam containing antimicrobials. As you can imagine the presence of these enzymes can result in resistance to susceptible antibiotics. # Beta lactams A beta lactam is a cyclic amide formed from a ring of 3 carbons and an amide. A change in the number of atoms comprising the ring changes the prefix for the lactam. ![[Pasted image 20250820165204.png|300]] oxyimino-beta-lactam CID: 129698282 Beta-lactam antibiotics are diverse and bactericidal; their mechanism of action results in cell death, not inhibition of growth like bacteriostatic antibiotics. They are analogues of d-alanyl-d-alanine and function mostly by irreversibly binding to penicillin binding proteins, inhibiting peptidoglycan (PtG) synthesis. Furthermore it is thought that the cells own lytic actions against its peptidoglycan contributes to bactericidal nature of these antibiotics- in order to regulate peptidoglycan synthesis, cell division and in response to the build up of peptidoglycan precursors (because of the inhibition of PBPs, in this case), autolyse their own peptidoglycan. For example lytic transglycosylases are bacterial enzymes that are both involved in the remodelling of PtG but also induce expression of beta lactamases. **References** - [Cho, H., Uehara, T. and Bernhardt, Thomas G. (2014). Beta-Lactam Antibiotics Induce a Lethal Malfunctioning of the Bacterial Cell Wall Synthesis Machinery. _Cell_, 159(6), pp.1300–1311. doi:https://doi.org/10.1016/j.cell.2014.11.017.](https://pmc.ncbi.nlm.nih.gov/articles/PMC4258230/#:~:text=Such%20enzymes%2C%20often%20referred%20to,the%20absence%20of%20TP%20activity.) - [Vollmer, W., Joris, B., Charlier, P. and Foster, S. (2008). Bacterial peptidoglycan (murein) hydrolases. _FEMS Microbiology Reviews_, [online] 32(2), pp.259–286. doi:https://doi.org/10.1111/j.1574-6976.2007.00099.x.](https://academic.oup.com/femsre/article/32/2/259/2683953) - [Yin, J., Sun, Y., Sun, Y., Yu, Z., Qiu, J. and Gao, H. (2018). Deletion of Lytic Transglycosylases Increases Beta-Lactam Resistance in Shewanella oneidensis. _Frontiers in Microbiology_, 9. doi:https://doi.org/10.3389/fmicb.2018.00013.](https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.00013/full)