Beta-lactamases in clinical isolates. Spectrum implications of sulbactam/ampicillin.

Combining ampicillin with an irreversible beta-lactamase inhibitor such as sulbactam is a promising technique for controlling infections due to resistant organisms. The combination not only restores the effectiveness of ampicillin against species that have acquired resistance to it, but it can extend the antimicrobial spectrum to species that have never exhibited susceptibility to ampicillin. However, the inhibition of beta-lactamases and the evaluation of inhibitors are still complicated by numerous factors known collectively as 'the epidemiology of beta-lactamases'. This refers to the distribution of enzymes in different bacterial species and in different geographical locations, the numerous types of enzymes, the variable number and amount of beta-lactamases that may exist in the same cell, and, of course, the potential for transfer of beta-lactamase resistance from one species to another.