Association of IS5 with divergent tandem bla(CMY-2) genes in clinical isolates of Escherichia coli

作者：Kurpiel Philip M; Hanson Nancy D^*

来源：Journal of Antimicrobial Chemotherapy, 2011, 66(8): 1734-1738.

DOI：10.1093/jac/dkr212

• AmpC
• insertion element
• gene copy number

Objective: To characterize a unique tandem bla(CMY-2) gene arrangement found in two non-identical clinical strains of Escherichia coli.
Methods: Both plasmid and chromosomal DNA were evaluated using PFGE, restriction digest analysis, plasmid profiling and Southern hybridization. bla(CMY-2) gene expression and gene copy number were evaluated by real-time PCR. Susceptibilities to selected beta-lactam antibiotics were determined by agar dilution.
Results: A tandem arrangement for bla(CMY-2) was identified in both isolates and was the only arrangement for bla(CMY-2) observed. These isolates had distinct PFGE and plasmid profiles. Each strain exhibited 2-fold higher bla(CMY-2) mRNA expression and up to 8-fold lower beta-lactam susceptibility compared with a strain with a single copy of bla(CMY-2).
Conclusion: This is the first report of IS5 being associated with tandem bla(CMY-2). IS5 has previously been associated with antibiotic resistance through tandem gene amplification. The unique tandem arrangement provides a mechanism for increased bla(CMY-2) expression.

• 出版日期2011-8