Bacitracin is a peptide antibiotic made by Bacillus subtilis and B. licheniformis, active against Gram-positive microbes. Used mainly in topical human medicine rather than systemically, it has also appeared in animal feeds as a growth promoter, where it modulated gut flora to improve performance. Residue and antimicrobial-resistance concerns have led regulators in several regions to restrict or ban its agricultural use, part of the wider move away from medically relevant antibiotics in livestock production. In food safety, bacitracin exemplifies the tension between useful antimicrobial tools and the need to preserve antibiotic effectiveness, a balance now struck through strict veterinary oversight and residue monitoring.