CFE-1, a novel plasmid-encoded AmpC beta-lactamase with an ampR gene originating from Citrobacter freundii.
A clinical isolate of Escherichia coli from a patient in Japan, isolate KU6400, was found to produce a plasmid-encoded beta-lactamase that conferred resistance to extended-spectrum cephalosporins and cephamycins. Resistance arising from production of a beta-lactamase could be transferred by either conjugation or transformation with plasmid pKU601 into E. coli ML4947. The substrate and inhibition profiles of this enzyme resembled those of the AmpC beta-lactamase. The resistance gene of pKU601, which was cloned and expressed in E. coli, proved to contain an open reading frame showing 99.8% DNA sequence identity with the ampC gene of Citrobacter freundii GC3. DNA sequence analysis also identified a gene upstream of ampC whose sequence was 99.0% identical to the ampR gene from C. freundii GC3. In addition, a fumarate operon (frdABCD) and an outer membrane lipoprotein (blc) surrounding the ampR-ampC genes in C. freundii were identified, and insertion sequence (IS26) elements were observed on both sides of the sequences identified (forming an IS26 composite transposon); these results confirm the evidence of the translocation of a beta-lactamase-associated gene region from the chromosome to a plasmid. Finally, we describe a novel plasmid-encoded AmpC beta-lactamase, CFE-1, with an ampR gene derived from C. freundii.
Nakano
Ryuichi
R
Department of Microbiology, School of Medicine and Environmental Infectious Disease, Graduate School of Medical Sciences, Kitasato University, Sagamihara, Kanagawa, Japan.
Okamoto
Ryoichi
R
Nakano
Yumiko
Y
Kaneko
Kenichi
K
Okitsu
Naohiro
N
Hosaka
Yoshio
Y
Inoue
Matsuhisa
M
D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D002876:Chromosomes, Bacterial / Q000235:genetics; D016971:Citrobacter freundii / Q000187:drug effects / Q000235:genetics*; D003001:Cloning, Molecular; D003227:Conjugation, Genetic / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics*
D000890:Anti-Infective Agents; D001426:Bacterial Proteins; C071526:AmpR protein, Bacteria; C048795:AmpC beta-lactamases; D001618:beta-Lactamases