In vitro activity of mastoparan-AF alone and in combination with clinically used antibiotics against multiple-antibiotic-resistant Escherichia coli isolates from animals

► Most Escherichia coli isolates from animals are found to contain multiple antimicrobial resistance genes. ► Mastoparan-AF exhibits potent antimicrobial activity against most E. coli isolates as compared with clinically used antibiotics tested. ► Mastoparan-AF shows rapid bactericidal activity against E. coli within a short period of time. ► Mastoparan-AF acts synergistically with cephalothin or gentamicin against antibiotic-resistant E. coli isolates.