Abstract: [Objective] To assess the antibacterial activity of an antibacterial peptide against a clinically isolated antibiotic resistant bacterial strain. [Method] A bacterial strain with antimicrobial resistance was isolated from the bloody stool sample of cattle with diarrhea by the resistant plate streaking method, and was subsequently identified by 16S rDNA PCR and sequencing. The antibiotic susceptibility test of the isolate was carried out via agar hole diffusion method with the antimicrobial agents of spectinomycin, ampicillin, kanamycin and chloramphenicol. The antibacterial activity of an antibacterial peptide against the isolate was evaluated. [Result] The obtained isolate was molecularly identified as Staphylococcus cohnii. It was sensitive to ampicillin but resistant to the other tested antimicrobial agents. The antibacterial peptide of different concentrations expressed obvious antibacterial activity against the isolate. [Conclusion] The antibacterial peptide can effectively inhibit the growth of antibiotic resistant Staphylococcus cohnii and has potential to serve as an alternative to antibiotics in livestock production.

Key words: antibacterial peptide, antibiotic, antibiotic resistant bacteria, antibacterial activity