The combination of Sulfadimidine and trimethoprim acts synergistically and usually
bactericidal against many Gram-positive and Gram-negative bacteria like E. coli, Haemophilus
Pasteurella Salmonella, Staphylococcus and Streptococcus spp. Both compounds aect
bacterial purine synthesis in a dierent way as a result, of which a double blockade is
accomplished.