Bacteria have evolved a variety of mechanisms to express resistance to beta-lactam antibiotics. beta-Lactamase-induced hydrolysis of the beta-lactam ring is the principal and most important mediator of clinically significant resistance. Almost 200 beta-lactamases have now been identified, of which class 1 chromosomal beta-lactamases, class 2beta plasmid-mediated beta-lactamases (especially TEM-1) and class 2be extended-spectrum beta-lactamases (ESBLS) are among the most important in respiratory pathogens. The combination of enzymatic and non-enzymatic resistance mechanisms has led to a steady rise in the prevalence of resistance to beta-lactams among isolates of the major respiratory pathogens, and, in turn, increasing rates of treatment failure, increased mortality, and prolonged morbidity. The combination of a beta-lactam antibiotic with a beta-lactamase inhibitor such as sulbactam, which protects the antibiotic from beta-lactamase destruction and so restores its activity, provides an innovative solution to this problem.