The combination of amoxycillin and colistin acts additive. Amoxycillin is a
semisynthetic broadspectrum penicillin with a bactericidal action against
both Gram-positive and Gram-negative bacteria. Amoxicillin is mainly
excreted in urine. A major part can also be excreted in bile. Colistin is an
antibiotic from the group of polymyxins with a bactericidal action against
Gram-negative bacteria like E. coli, Haemophilus and Salmonella.