Molecular characterization of SPM-1, a novel metallo-beta-lactamase isolated in Latin America: report from the SENTRY antimicrobial surveillance programme

J Antimicrob Chemother. 2002 Nov;50(5):673-9. doi: 10.1093/jac/dkf210.


The gene encoding the metallo-beta-lactamase SPM-1 was cloned from a genomic library of Pseudomonas aeruginosa strain 48-1997 A. The insert carrying spm-1 possessed a GC content of 47%, indicating that it is of non-Pseudomonas origin. Upstream of spm-1 there is a small open reading frame (ORF), which is homologous to the LysR family of proteins (69% identity to the LysR protein from Salmonella enterica serovar Typhimurium). Downstream of spm-1 there is the start of an ORF, the product of which shows close homology with the GroEL-type proteins from Xanthomonas campestris. No transmissible element could be identified upstream or downstream of spm-1. The spm-1 gene is carried on a plasmid that can transform both Escherichia coli and P. aeruginosa to ceftazidime resistance. SPM-1 contains the classic metallo-beta-lactamase zinc-binding motif HXHXD and shows the highest identity (35.5%) to IMP-1. SPM-1 is a distinctly different metallo-beta-lactamase from VIM and IMP and, accordingly, represents a new subfamily of mobile metallo-beta-lactamases. The predicted molecular weight of the protein was 27 515 Da, significantly higher than that of IMP (25 041 Da) or VIM (25 322 Da). SPM-1 possesses a unique loop of 23 residues that accounts for the higher molecular mass.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence / genetics
  • Gene Expression Regulation, Enzymologic / physiology*
  • Humans
  • Latin America
  • Molecular Sequence Data
  • Pseudomonas aeruginosa / enzymology*
  • Pseudomonas aeruginosa / genetics
  • beta-Lactamases / biosynthesis
  • beta-Lactamases / chemistry
  • beta-Lactamases / genetics*
  • beta-Lactamases / isolation & purification*


  • beta-lactamase IMP-1
  • beta-Lactamases