Researchers tested the natural antimicrobial peptide LL-37 and two shorter versions (LL-13 and LL-17) against tough Staph infections. When mixed with the antibiotic vancomycin, the short peptides helped kill vancomycin‑resistant strains and even made them sensitive to the drug again. They also stopped the bacteria from forming protective biofilm layers.

Treatment of Staphylococcus aureus infections continues to be a challenge due to antimicrobial resistance. Endogenous antimicrobial peptides may offer a new option for treating S. aureus infections but several factors limit their clinical utility. Herein, we studied the activity of the antimicrobial peptide LL-37 and two truncated derivatives, LL-13 and LL-17 alone and in combination with vancomycin against a range of drug-resistant S. aureus strains including methicillin resistant S. aureus (MRSA) and vancomycin resistant S. aureus (VRSA) strains in vitro. When used with vancomycin, LL-13 and LL-17 displayed synergy against VRSA and showed the ability to restore sensitivity to vancomycin after pretreatment. In addition, LL-13 and LL-17 showed a strong ability to inhibit S. aureus biofilm production. LL-37 derivatives may be useful in treating infections that are resistant to vancomycin or in scenarios where biofilm formation is a concern.