Wasp Venom Peptide (Polybia MP-1) Shows Antimicrobial Activity Against Multi Drug Resistant Bacteria Isolated from Mastitic Cow Milk

Increase in the incidence of Antimicrobial Resistance (AMR) in pathogens is a major concern for the human and animal health sector alike. AMR has been widely reported in bacteria that cause mastitis in dairy cattle. Antimicrobial peptides (AMPs) offer a lucrative and effective alternative to antibiotics for the treatment of mastitis. The Polybia MP-1 is a 14 amino acid long AMP obtained from the venom of the wasp Polybia paulista . In the present study, antimicrobial activity of Polybia MP-1 was evaluated against Staphylococcus aureus , Escherichia coli and Klebsiella pneumoniae isolates obtained from mastitic milk samples. In all, 20 S. aureus , 21 E. coli and 14 K . pneumoniae isolates were obtained from 40 mastitic milk samples. Antibiotic susceptibility of the isolates was determined by antibiotic disc diffusion assay and 19 S. aureus , 17 E. coli and 10 K . pneumoniae isolates were found to be multiple drug resistant (MDR) isolates. The synthetic Polybia MP-1 peptide effectively inhibited 32% (6/19) S. aureus , 47% (8/17) E. coli and 70% (7/10) K. pneumoniae MDR isolates. The peptide disrupted both the outer and inner bacterial membrane and at the same time showed very low haemolytic activity for mice and rabbit erythrocytes even up to 200 µM concentration. Moreover, it had no cytotoxic effect in Vero cells up to 160 µM concentration as assessed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide) dye reduction assay. The peptide did not result in mortality of the Galleria mellonella larvae up to a dose of 40 mg per kg bodyweight. These findings indicate that the Polybia MP-1 peptide is safe and can be effectively tried as an alternative to antibiotic for management of mastitis in cattle.