Comparison of In vitro Antibacterial Activity of Florfenicol with Chloramphenicol in Combination with TMP and OMP

The MIC determinations of florfenicol,chloramphenicol,TMP and OMP,against1 5iso- lates of veterinary origin were performed using the method of broth two-fold dilutions firstly.Then, the FICs of florfenicol+TMP,florfenicol+OMP,chloramphenicol+TMP,and chloramphenicol+ OMP were determined with checkerboard system respectively.The results showed thatflorfenicol was more active than orequivalentto chloramphenicol.TMPand OMP showed low activity,although OMP was more active than TMP.Florfenicol and chloramphenicol were synergistic with TMP in 50 %of the in vitro models,but were both synergistic with OMP in2 8.6%of the in vitro models.In general,flor- fenicol and chloramphenicol showed synergy with TMP and OMP in 3 9.3 %of the in vitro models a- gainst1 4strains pathogenic bactera,and there was no antagonism between them.So it′s necessary to perform combining sensitivity testbefore combining administration of these drugs in clinical situation.