[Identification of a plasmid-mediated AmpC beta-lactamase from clinical isolates of Escherichia coli and Klebsiella pneumoniae].
OBJECTIVE
To investigate the susceptibility and genotype characteristics of Escherichia coli and Klebsiella pneumoniae producing plasmid-mediated AmpC beta lactamase.


METHODS
A total of 110 strains of Escherichia coli and Klebsiella pneumoniae were collected from patients hospitalized in our respiratory ward during January 2002-May 2004. The isolates harboring AmpC beta-lactamase were detected by three-dimensional test, and isoelectric focusing analysis, electroporation, PCR and DNA sequencing were performed to determine the genotypes.


RESULTS
AmpC enzyme was detected in 9.30% (4/43) of the Escherichia coli isolates and 4.48% (3/67) of the Klebsiella pneumoniae isolates. The susceptibility test showed 7 isolates tested were all resistant to cefoxitin, and part of these strains were resistant to the third-generation cephalosporins, beta-lactams/beta-lactamase inhibitors, aztreonam, amikacin and ciprofloxacin, but most of them were susceptible to cefepime and imipenem. Three strains of Klebsiella pneumoniae and 2 strains of Escherichia coli transferred cefoxitin-resistance to recipients by electroporation. Results of PCR and DNA sequencing defined them to be DHA-1 AmpC beta-lactamase.


CONCLUSIONS
Escherichia coli and Klebsiella pneumoniae producing plasmid-mediated AmpC beta lactamase were isolated from clinical strains in this hospital, and its gene can be transferred horizontally.
Wang
Yu
Y
Respiratory Diseases Research Institute, First Affiliated Hospital, China Medical University, Shenyang 110001, China.
Li
Zhen-hua
ZH
D001426:Bacterial Proteins / Q000235:genetics*; D004269:DNA, Bacterial; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D010957:Plasmids; D001618:beta-Lactamases / Q000235:genetics*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; C048795:AmpC beta-lactamases; D001618:beta-Lactamases