A cathelicidin-2-derived peptide effectively impairs Staphylococcus epidermidis biofilms

Staphylococcus epidermidis is a major cause of nosocomial infections owing to its ability to form biofilms on the surface of medical devices. Biofilms are surface-adhered bacterial communities. In mature biofilms these communities are encased in an extracellular matrix composed of bacterial polysaccharides, proteins and DNA. The antibiotic resistance of bacteria present in biofilms can be up to 1000-fold higher compared with the planktonic phenotype. Host defence peptides (HDPs) are considered to be excellent candidates for the development of novel antibiotics. Recently, we demonstrated that a short variant of the HDP chicken cathelicidin-2, peptide F2,5,12W, has potent antibacterial and lipopolysaccharide-neutralising activities. This study reports on the antibiofilm activity of peptide F2,5,12W against two strains of S. epidermidis, including a multiresistant strain. Peptide F2,5,12W potently inhibited the formation of bacterial biofilms in vitro at a low concentration of 2.5 μM, which is below the concentration required to kill or inhibit growth (minimal inhibitory concentration = 10 μM). Moreover, peptide F2,5,12W also impaired existing S. epidermidis biofilms. A 4-h challenge of pre-grown biofilms with 40 μM F2,5,12W reduced the metabolic activity of the wild-type strain biofilm completely and reduced that of the multiresistant strain biofilm by >50%. It is concluded that F2,5,12W prevents biofilm formation and impairs mature S. epidermidis biofilms.