Topic overview

Start with the big picture

The lesson connects β-lactam ring hydrolysis with loss of antibiotic activity, then examines how genes carried on mobile elements can spread resistance. It introduces the Ambler classes, including the distinction between serine enzymes and zinc-dependent metallo-β-lactamases, before focusing on class A ESBLs. The topic covers their activity against extended-spectrum cephalosporins and aztreonam, inhibition by β-lactamase inhibitors, major enzyme families, and commonly associated pathogens. It also outlines phenotypic and molecular detection, co-resistance, clinical treatment considerations, and infection-control measures. Comparisons with AmpC enzymes and carbapenemases help clarify why identifying the resistance mechanism matters. The preview provides a framework for these concepts; the full lesson develops their clinical context and distinctions in greater detail.