In vitro evaluation of SF-2103A, a novel carbapenem antibiotic, as a beta-lactamase inhibitor.

SF-2103A, a new carbapenem antibiotic, exhibited a broad antibacterial spectrum and a potent inhibitory activity against a wide range of beta-lactamases, in particular, against cephalosporinases, with lower I50 values than those displayed by sulbactam and clavulanic acid. Using a fixed combination and checkerboard titration, in vitro synergy against the majority of the beta-lactamase-producing strains tested was demonstrated between SF-2103A and various beta-lactam antibiotics, especially cefotaxime, ceftizoxime, and cefoperazone. The synergistic effect of SF-2103A was more pronounced than that of sulbactam. The in vitro synergy was also confirmed by bactericidal and bacteriolytic activities and morphological effects.