细菌对β—内酰胺类抗生素(青霉素类、头孢菌素类及其相关抗生素如头霉素类、青霉烯类、碳青霉烯类和单酰胺菌素类)产生耐药性的最重要机理是产生β—内酰胺酶。该酶能水解药物分子中的β—内酰胺键而使其失活。对于青霉素类,反应产物是青霉噻唑酸。头孢菌素类等则分解为较小分子产物。许多细菌产生β—内酰胺酶,一些细菌编码酶的基因位于染色体上,其余的则由染色体外成份介导,或由质粒介导,或由转座子介导。 Most importantly bacterial resistance to β-lactam antibiotics (penicillins, cephalosporins and their related antibiotics such as cephamycins, penem carbenicillins and monoclofen-class) The mechanism is to produce beta-lactamase. This enzyme hydrolyzes the β-lactam bond in the drug molecule inactivating it. For penicillins, the reaction product is penicillin. Cephalosporins are broken down into smaller molecules. Many bacteria produce beta-lactamase. Some bacteria encode genes for the enzyme on chromosomes and the rest are mediated by extrachromosomal elements, either plasmid-mediated or transposon-mediated.