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- Title
Increase in ampC promoter strength due to mutations and deletion of the attenuator in a clinical isolate of cefoxitin-resistant Escherichia coli as determined by RTPCR.
- Authors
Dobryan M. Tracz; David A. Boyd; Louis Bryden; Romeo Hizon; Sandra Giercke; Paul Van Caeseele; Michael R. Mulvey
- Abstract
Objectives: To characterize the mechanism of cefoxitin resistance in clinical isolate Escherichia coli N99-0001.Methods: Plasmid analysis, PCR for -lactamases, and sequencing of the ampC genes was carried out. An RTPCR method was developed to determine relative ampC expression.Results: Analysis of the ampC promoter region of E. coli N99-0001 revealed a T?A mutation at -32, a C?A mutation at -11, an insertion of a T between -20 and -21, and a 28?bp deletion including the entire attenuator. RTPCR showed that ampC was expressed 140-fold higher in E. coli N99-0001 than in E. coli ATCC 25922.Conclusions: Cefoxitin resistance in E. coli N99-0001 was due to overexpression of ampC caused by an increase in promoter strength.
- Subjects
ESCHERICHIA coli; GENETIC mutation; MOBILE genetic elements; GENES
- Publication
Journal of Antimicrobial Chemotherapy (JAC), 2005, Vol 55, Issue 5, p768
- ISSN
0305-7453
- Publication type
Article
- DOI
10.1093/jac/dki074