In-vitro activity of ticarcillin with and without clavulanic acid against clinical isolates of gram-positive and gram-negative bacteria.

The in-vitro activity of ticarcillin with and without clavulanic acid was investigated against 285 freshly isolated clinical strains of Gram-positive and Gram-negative bacteria by the agar-dilution technique on Mueller-Hinton-agar. Clavulanic acid had an excellent or moderate potentiating effect on the in-vitro activity of ticarcillin against staphylococci, Escherichia coli, Klebsiella spp., Enterobacter aerogenes, Proteus mirabilis, Citrobacter spp., Acinetobacter, Haemophilus influenzae and Bacteroides spp. No effect was seen against enterococci, indole-positive Proteus spp., Ent. cloacae, Serratia marcescens and Pseudomonas aeruginosa. The effect of clavulanic acid was dose- and inoculum-dependent.