A 34-year-old woman with a history of recurrent urinary tract infections is found to have a urinary isolate of Escherichia coli that is resistant to ampicillin, amoxicillin-clavulanate, and cephalosporins, but remains susceptible to carbapenems and fluoroquinolones. The isolate produces a positive Extended-Spectrum Beta-Lactamase (ESBL) test. Which of the following mechanisms best explains the resistance pattern observed in this isolate?