Susceptibility difference between methicillin-susceptible and methicillin-resistant Staphylococcus aureus to a bovine myeloid antimicrobial peptide (BMAP-28).

A bovine myeloid antimicrobial peptide antimicrobial peptide (BMAP-28) is a member of the cathelicidin family and acts as a component of innate immunity. There are few reports of susceptibility difference of methicillin-resistant Staphylococcus aureus (MRSA) and susceptible strains (MSSA) against BMAP-28. This study aims to clarify how a few amino acid substitutions of BMAP-28 are related to its antimicrobial activity using four analog peptides of BMAP-28. We also compared cellular fatty acid components of MSSA and MRSA using gas chromatography. We found that a few amino acid substitutions of BMAP-28 do not change antimicrobial activity. It was also revealed that the percentage of cis-11-eicosenoic acid in total detected fatty acids of MRSA was significantly higher than that of MSSA. In addition, the percentage of palmitic acid in total detected fatty acids of MRSA tended to be lower than that of MSSA. Our results will provide new information to deal with the question of differences in bacterial susceptibility against BMAP-28.