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Amp Cβ-内酰胺酶是属 Bush功能分类 群 ,Ambler分子分类 C类的头孢菌素酶 ,主要由染色体介导产生 ,不被克拉维酸抑制 ,能水解第三代头孢菌素、头霉素等广谱 β-内酰胺类抗生素。Amp Cβ-内酰胺酶的表达受amp复合操纵子调控 ,与肽聚糖合成密切相关。amp复合操纵子由 amp C、amp R、amp D和 amp G构成 ,分别编码Amp Cβ-内酰胺酶、转录调节因子 Amp R,N-乙酰葡萄糖胺 - L-丙氨酸酰胺酶 Amp D和膜结合转运蛋白 Amp G。其中 Amp R与 UDP- N-乙酰胞壁酰五肽结合可抑制 amp C转录 ,与 N-乙酰胞壁酰酐三肽结合可激活 amp C转录。调控基因突变及 β-内酰胺类抗生素的诱导作用均可使肽聚糖合成与水解反应失衡 ,导致 N-乙酰胞壁酰酐肽积聚 ,从而使 Amp Cβ-内酰胺酶的产量提高。近年来 ,质粒编码的 Amp Cβ-内酰胺酶逐渐增多 ,源于肠杆菌科细菌 ,与染色体编码的 Amp Cβ-内酰胺酶在分子结构上具不同程度的同源性。Amp Cβ-内酰胺酶的诱导产生及质粒编码的Amp Cβ-内酰胺酶的出现是细菌针对抗生素造成的选择压力而进化的结果 ,临床实践中必须慎用超广谱 β-内酰胺类抗生素。
Amp C beta-lactamase is a Bush functional taxa, Ambler molecular classification of C cephalosporins, mainly mediated by the chromosome, not by clavulanic acid inhibition, can hydrolyze the third generation cephalosporins, cephamycin Broad-spectrum β-lactam antibiotics. The expression of Amp C beta-lactamase is regulated by the amp complex operon and is closely related to peptidoglycan synthesis. Amp complex operon consists of amp C, amp R, amp D and amp G encoding Amp C beta-lactamase, transcriptional regulator Amp R, N-acetylglucosamine-L-alanine amidase Amp D and membrane Binding to transporter AmpG. Among them Amp R binds to UDP-N-acetylmuramylpeptide to inhibit amp C transcription and binds to N-acetylmuramide tripeptide to activate amp C transcription. Regulation of gene mutations and β-lactam antibiotic induction can peptidoglycan synthesis and hydrolysis reaction imbalance, resulting in N-acetylmuramic acid peptide accumulation, so that the Amp C β-lactamase production increased. In recent years, plasmid-encoded Amp C beta -lactamase gradually increased, derived from Enterobacteriaceae and the chromosome-encoded Amp C beta-lactamase in molecular structure with varying degrees of homology. The induction of Amp C beta -lactamases and the appearance of plasmid-encoded Amp C beta -lactamases are the result of the evolution of bacterial selection pressure due to antibiotics, and extended use of beta-lactam antibiotics must be used with caution in clinical practice.