Post-antibiotic effect of the antimicrobial peptide lactoferricin on Escherichia coli and Staphylococcus aureus

Lactoferricin is an antimicrobial peptide generated by gastric pepsin cleav age of lactoferrin. A possible post-antibiotic effect (PAE) of bovine lacto ferricin (Lfcin B) and two shorter peptide derivatives against Staphylococc us aureus and Escherichia coli was studied. A drug removal technique involv ing centrifugation and washing was used. No PAE was found for Lfcin B again st these two bacteria. The shorter derivatives had a short PAE against E. c oli. They had a short negative PAE against S. aureus. In conclusion, the ov erall PAE is not overwhelming, but the small differences found between the different peptide-bacteria combinations could indicate that different pepti de mechanisms of action might be present.