Beta-lactamase CTX-M (CTX-M)

Beta-lactamase CTX-M (Cefotaximase from Munich) is a family of Ambler Class A extended-spectrum beta-lactamases (ESBLs) that has emerged as the most prevalent cause of resistance to third-generation cephalosporins in Gram-negative bacteria globally [1, 8, 11]. These enzymes are primarily found in Enterobacteriaceae, such as Escherichia coli and Klebsiella pneumoniae, and are typically encoded on mobile genetic elements like plasmids, facilitating their rapid dissemination across different bacterial species [2, 12, 13]. CTX-M enzymes are distinguished by their high hydrolytic efficiency against oxyimino-cephalosporins, particularly cefotaxime and ceftriaxone, which are critical first-line treatments for serious infections [4, 8, 16]. Their presence in clinical isolates often leads to therapeutic failure with standard beta-lactam treatments, necessitating the use of carbapenems or specialized beta-lactam/beta-lactamase inhibitor combinations [13, 15]. Drugs targeting CTX-M include traditional inhibitors like tazobactam and newer agents such as avibactam and vaborbactam, which work by covalently binding to the enzyme's active site to prevent antibiotic degradation [1, 6, 15]. The global spread of CTX-M, particularly the CTX-M-15 variant, represents a major public health challenge due to its association with multi-drug resistant high-risk clones [11, 13].

Other names

CefotaximaseCTX-M-type beta-lactamaseExtended-spectrum beta-lactamase CTX-MToho-1-like beta-lactamaseMEN-1FEC-1

Inhibition of the enzyme's catalytic activity through covalent binding to the active site serine residue, thereby preventing the hydrolysis of co-administered beta-lactam antibiotics and restoring their antibacterial efficacy.