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A Protocol for Functional Assessment of Whole-Protein Saturation Mutagenesis Libraries Utilizing High-Throughput Sequencing
Published on: July 3, 2016
Plasmid-mediated beta-lactamase (TEM-7) involved in resistance to ceftazidime and aztreonam
L Gutmann1, M D Kitzis, D Billot-Klein
1Laboratoire de Microbiologie Médicale, Université Pierre et Marie Curie, Paris, France.
Abstract:
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.
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