Characterization of a novel plasmid-mediated cephalosporinase (CMY-9) and its genetic environment in an Escherichia coli clinical isolate

Yohei Doi, Naohiro Shibata, Keigo Shibayama, Kazunari Kamachi, Hiroshi Kurokawa, Keiko Yokoyama, Tetsuya Yagi, Yoshichika Arakawa

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50 Citations (Scopus)


An Escherichia coli strain, HKYM68, which showed resistance to broad-spectrum cephalosporins was isolated from a sputum specimen in Japan. The high-level resistance of the strain to ceftazidime, cefpirome, and moxalactam was carried by a self-transferable plasmid. The β-lactamase gene responsible for the resistance was cloned and sequenced. The deduced amino acid sequence of this gene product, CMY-9, had a single amino acid substitution (E85D), the residue reported to be part of the recognition site for the R1 side chain of β-lactams, compared with the amino acid sequence of CMY-8 and also had 78% identity with the amino acid sequence of CepH, a chromosomal cephalosporinase of Aeromonas hydrophila. A sull-type class 1 integron containing an aacA1-orfG gene cassette was identified upstream of blaCMY-9 and ended with a truncated 3′ conserved segment. The following 2.1 kb was almost identical to the common region of integrons In6 and In7 and the integron of pSAL-1, except that orf513 encoding a putative transposase was identified instead of orf341 due to addition of a single nucleotide. blaCMY-9 was closely located downstream of the end of the common region. These observations are indicative of the exogenous derivation of blaCMY-9 from some environmental microorganisms such as aeromonads.

Original languageEnglish
Pages (from-to)2427-2434
Number of pages8
JournalAntimicrobial agents and chemotherapy
Issue number8
Publication statusPublished - 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases


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