Date of Award
Master of Science
Cefepime is a fourth-generation cephalosporin approved by the FDA in 1996 (Barlow 2003). Few instances of cefepime resistance have been reported. This research used directed molecular evolution involving error-prone rolling circle amplification on plasmids containing the beta-lactamase gene designated as bla-cmy-2. This gene is believed to be responsible for the majority of the nontyphoidal Salmonella enterica cephalosporin antimicrobial resistance in this country (Daniels 2007). Plasmids were removed from Salmonella and Yersinia bacteria exhibiting resistance to the following third-generation cephalosporins: ceftiofur, cefotaxime, cefixime, ceftriaxone, and ceftazidime. The goals of this research were to identify bla-cmy-2 mutations that confer cefepime resistance. Error-prone rolling circle amplification yielded a mutation encoding cefepime resistance. This mutation altered the secondary structure in the region of the H-10 helix, which is a part of the catalytic site for extended-spectrum beta-lactamases. In summary, bla-cmy-2 mutations are sources of resistance for extended-spectrum beta-lactamases that can use fourth-generation cephalosporins as substrates in E. coli.
Moore, Wellington, "Directed molecular evolution of fourth-generation cephalosporin resistance in" (2011). Graduate Theses and Dissertations. 10107.