Plasmid-mediated beta-lactamase (TEM-7) involved in resistance to ceftazidime and aztreonam.
TEM-7, a novel TEM-type beta-lactamase (pI 5.41) encoded on a plasmid of approximately 85 kilobases, was found in a clinical isolate of Citrobacter freundii. Strains containing this enzyme exhibited decreased susceptibility to ceftazidime (64-fold) and aztreonam (16-fold) but not to other third-generation cephalosporins. Addition of a beta-lactamase inhibitor--clavulanic acid, sulbactam, or YTR 830--restored normal susceptibility to associated compounds such as ampicillin, piperacillin, ceftazidime, and aztreonam. DNA-DNA hybridization of an intragenic probe of TEM-1 occurred with a 19-kilobase EcoRI fragment of the plasmid encoding TEM-7. A TEM-2 derivative, TEM-201, with characteristics similar to those of TEM-7 was selected spontaneously in the presence of ceftazidime in vitro.
Gutmann
L
L
Laboratoire de Microbiologie Médicale, Université Pierre et Marie Curie, Paris, France.
Kitzis
M D
MD
Billot-Klein
D
D
Goldstein
F
F
Tran Van Nhieu
G
G
Lu
T
T
Carlet
J
J
Collatz
E
E
Williamson
R
R
D001398:Aztreonam / Q000378:metabolism / Q000494:pharmacology*; D002442:Ceftazidime / Q000378:metabolism / Q000494:pharmacology*; D002954:Citrobacter / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D010957:Plasmids; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
D002442:Ceftazidime; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1; D001398:Aztreonam