Florfenicol is a broad-spectrum antibiotic that has activity against many bacteria. It acts by binding to 50S ribosome, thereby inhibiting bacterial protein synthesis. Florfenicol has activity against gram-positive bacteria such as Staphylococcus aureus, Streptococci and gram-negative bacteria such as Pasteurella multocida, Pasteurella haemolytica and Histophilus somni.