This 29 amino acid sheep myeloid antimicrobial peptide 29 (SMAP 29) displays extremely high antimicrobial activity against Pseudomonas strains, other gram-negative bacteria, and multidrug-resistant pathogens. SMAP 29 is a broad-spectrum antibiotic cathelicidin, it is active in both low- and high-ionic-strength conditions, and induces significant morphological alterations in bacterial surfaces.