[In vitro activity of the combination ticarcillin-clavulanic acid on bacterial isolates in surgery]

The in vitro activity of ticarcillin in combination with clavulanic acid was tested, by disc diffusion, against 1,380 clinical bacterial isolates and was compared with that of ticarcillin alone. 83.8% of the isolates were susceptible to ticarcillin + clavulanic acid, whereas 56.6% were susceptible to ticarcillin alone. Minimal inhibitory concentrations (MIC) of ticarcillin in the presence of 4 micrograms/ml of clavulanic acid were determined against 157 ticarcillin resistant (MIC greater than 128 micrograms/ml) but ticarcillin + clavulanic acid susceptible strains of Gram negative bacilli and against 20 strains of beta-lactamase producing Staphylococcus aureus. With the addition of clavulanic acid, MICs of ticarcillin were respectively less than or equal to 16 micrograms/ml and less than or equal to 64 micrograms/ml for 50 and 90% of the Gram negative bacilli. All the Staphylococcus aureus were inhibited by concentrations of ticarcillin less than or equal to 1 microgram/ml.