Characterization of a novel plasmid-mediated cephalosporinase (CMY-9) and its genetic environment in an Escherichia coli clinical isolate.
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 beta-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 beta-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 sul1-type class 1 integron containing an aacA1-orfG gene cassette was identified upstream of bla(CMY-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. bla(CMY-9) was closely located downstream of the end of the common region. These observations are indicative of the exogenous derivation of bla(CMY-9) from some environmental microorganisms such as aeromonads.
Department of Bacterial Pathogenesis and Infection Control, National Institute of Infectious Diseases, 4-7-1 Gauken, Musashi-murayama, Tokyo 208-0011, Japan. yohei@nih.go.jp
Yohei
Y
Doi
Naohiro
N
Shibata
Keigo
K
Shibayama
Kazunari
K
Kamachi
Hiroshi
H
Kurokawa
Keiko
K
Yokoyama
Tetsuya
T
Yagi
Yoshichika
Y
Arakawa
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D002510:Cephalosporinase / Q000235:genetics*; D002511:Cephalosporins / Q000494:pharmacology; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics; D007525:Isoelectric Focusing; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001618:beta-Lactamases / Q000235:genetics
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C470186:CMY-9 protein, E coli; D002510:Cephalosporinase; D001618:beta-Lactamases