Characterisation of CMY-4, an AmpC-type plasmid-mediated beta-lactamase in a Tunisian clinical isolate of Proteus mirabilis

FEMS Microbiol Lett. 1998 Dec 15;169(2):235-40. doi: 10.1111/j.1574-6968.1998.tb13323.x.


A strain of Proteus mirabilis resistant to beta-lactams, including cefoxitin, was isolated from the urine of a woman from Tunisia. Its antibiotic susceptibility pattern and that of the Escherichia coli transconjugant suggested the presence of an AmpC-type beta-lactamase. Two bands of beta-lactamase activity (pI 5.4 and 9.2) were detected by isoelectric focusing. The nucleotide sequence of the gene encoding the AmpC-type enzyme was determined. The deduced amino acid sequence was 98-99% identical to CMY-3 and to those of the plasmid-mediated AmpC-type beta-lactamases originated from Citrobacter freundii and 97% identical to the chromosome-encoded beta-lactamase of a Tunisian clinical isolate of C. freundii. This enzyme differs from CMY-2 by one substitution (Arg for Trp at position 221) and from CMY-3 by two substitutions (Glu for Gly at position 42 and Ser for Asn at position 363) and we propose the denomination CMY-4.

MeSH terms

  • Aged
  • Amino Acid Sequence
  • Bacterial Proteins / genetics*
  • Base Sequence
  • Cefoxitin / pharmacology
  • Cephamycins / pharmacology
  • Citrobacter freundii / enzymology
  • Citrobacter freundii / genetics
  • Drug Resistance, Microbial / genetics
  • Female
  • Genes, Bacterial / genetics
  • Humans
  • Molecular Sequence Data
  • Proteus mirabilis / drug effects
  • Proteus mirabilis / enzymology*
  • R Factors / genetics
  • Sequence Homology, Amino Acid
  • beta-Lactamases / genetics*


  • Bacterial Proteins
  • Cephamycins
  • Cefoxitin
  • beta-Lactamases

Associated data

  • GENBANK/Y15129
  • GENBANK/Y15130