CTX-M-type beta-lactamases: an emerging group of extended-spectrum enzymes

Int J Antimicrob Agents. 2000 Mar;14(2):137-42. doi: 10.1016/s0924-8579(99)00165-x.


CTX-M-type beta-lactamases constitute a novel group of class A beta-lactamases with extended-spectrum properties. They are encoded by transferable plasmids and found in various enterobacteria, mostly Salmonella typhimurium, Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. CTX-M enzymes share extensive sequence similarity with the chromosomal beta-lactamases of Klebsiella oxytoca. They efficiently hydrolyze many newer broad-spectrum oximino-beta-lactams including cefotaxime, ceftriaxone and aztreonam and are readily inhibited by tazobactam and clavulanate. CTX-M-producing enterobacteria are endemic in Latin America and in some areas of North Eastern Europe. Data on their structure, properties and epidemiology are discussed.

MeSH terms

  • Amino Acid Sequence
  • Bacterial Infections / enzymology
  • Bacterial Infections / epidemiology
  • Bacterial Infections / microbiology
  • Drug Resistance, Microbial
  • Humans
  • Protein Conformation
  • beta-Lactamases / chemistry
  • beta-Lactamases / metabolism*


  • beta-Lactamases