PS-5, a new .BETA.-lactam antibiotic. III. Synergistic effects and inhibitory activity against a .BETA.-lactamase.

Abstract

PS-5 was shown to have synergistic activity in combination with other β-lactam antibiotics and it markedly decreased the minimum inhibitory concentration values of ampicillin or cephaloridine with a β-lactamase-producing Proteus vulgaris strain on agar plates. The synergistic activities were also shown in bactericidal activity in liquid medium. PS-5 was shown to be inhibitory against an extracted β-lactamase of P. vulgaris.