Pseudomonic acid is an antibiotic and bacterial metabolite that has been found inP. fluorescens.¹It is bacteriostatic againstS. aureus(MIC = 0.05 µg/ml) and active against skin wound clinical isolates of methicillin-resistantS. aureus(MRSA; MICs = 1-4 µg/ml).^2,3Pseudomonic acid inhibits MRSA andP. aeruginosabiofilm formationin vitro.⁴It inhibits bacterial cell wall isoleucyl-tRNA synthetase, slowing bacterial growth.^2,4Topical administration of pseudomonic acid (2% v/v) reduces the number of wound colony forming units (CFUs) in a mouse model of MRSA skin infection.³

1.Fuller, A.T., Mellows, G., Woolford, M., et al.Psuedomonic acid: An antibiotic produced by Pseudomonas fluorescensNature234(5329)416-417(1971) 2.Hughes, J., and Mellows, G.On the mode of action of pseudomonic acid: Inhibition of protein synthesis in Staphylococcus aureusJ. Antibiot. (Tokyo)31(4)330-335(1978) 3.Mohammad, H., Cushman, M., and Seleem, M.N.Antibacterial evaluation of synthetic thiazole compounds in vitro and in vivo in a methicillin-resistant Staphylococcus aureus (MRSA) skin infection mouse modelPLoS One10(11)e0142321(2015) 4.Khoshnood, S., Heidary, M., Asadi, A., et al.A review on mechanism of action, resistance, synergism, and clinical implications of mupirocin against Staphylococcus aureusBiomed. Pharmacother.1091809-1818(2019)