The in vitro antibacterial activity of florfenicol in combination with amoxicillin or cefuroxime against pathogenic bacteria of animal origin

This study evaluated the in vitro activity of florfenicol (F) in combination with amoxicillin (AM) or cefuroxime (CRM) against pathogenic bacteria of animal origin, including E. coli, S. aureus, S. cholerasuis and P. mirabilis. The MIC of AM ranged from 16 to 256 mug/ml. The MBC of AM (64 mug/ml) was four-fold higher than its MIC value (16 mug/ml) for E. coli, and similar to the MIC for the other three species. The MIC of F ranged from 8 to 16 mug/ml. The MBC values of F for E. coli, S. aureus, and S. cholerasuis were eight-fold higher than the respective MIC values, and 32-fold higher than the MIC of P. mirabilis. The MIC of CRM ranged from 8 to 128 mug/ml. The MBC of CRM was the highest (greater than 256 mug/ml), except for E. coli. The F/AM combination resulted in synergism (FIC index less than or equal to 0.5) for E. coli, S. aureus, and P. mirabilis and in-difference (FIC index greater than 1) for S. cholerasuis. For F/CRM combination, synergism (E. coli and S. choleras