In vitro activity of ticarcillin plus clavulanic acid (BRL 28500, 'Timentin') against ticarcillin-resistant gram-negative rods.

A study was carried out to investigate the in vitro susceptibility of 211 clinical isolates of ticarcillin resistant (MICs greater than 128 micrograms/ml) Gram-negative rods to a combination of ticarcillin plus clavulanic acid. The combination demonstrated superior activity; 90% of the Proteus spp. and 50% of E. coli and Klebsiella spp. isolates were inhibited at a concentration of 64 micrograms/ml. It was 2 to 8-times more active than ticarcillin alone against E. coli, Proteus and Klebsiella spp. in half to three-quarters of the strains under test. This enhanced activity was only marginal, however, against Enterobacter, Acinetobacter, Citrobacter, Serratia and Pseudomonas spp. Against 161 ticarcillin sensitive strains the combination did not have any potentiation effect.