Background: Antimicrobial research is being focused to look for more effective therapeutics
against antibiotic-resistant infections caused by methicillin-resistant Staphylococcus aureus (MRSA). In
this direction, antimicrobial peptides (AMP) appear as promising tool.
Objectives: This study evaluated the antimicrobial activity of different AMPs (Citropin 1.1, Temporin
A, Pexiganan, CA(1–7)M(2–9)NH2, Pal-KGK-NH2, Pal-KKKK-NH2, LL-37) against human MRSA
Methods: The Minimum Inhibitory Concentration (MIC) was assessed for each AMP; then, the most
active ones (Citropin 1.1, Temporin A, CA(1–7)M(2–9)NH2 and Pal-KGK-NH2) were tested against
selected MRSA strains by time-kill studies.
Results: The lowest MIC value was observed for Pal-KGK-NH2 (1 µg/ml), followed by Temporin A (4-
16 µg/ml), CA(1–7)M(2–9)NH2 (8-16 µg/ml) and Citropin 1.1 (16-64 µg/ml), while higher MICs were
evidenced for LL-37, Pexiganan and Pal-KKKK-NH2 (> 128 µg/ml). In time-kill experiments, Citropin
1.1 and CA(1-7)M(2-9)NH2 showed a relatively high percentage of growth inhibition (>30 %) for all the
tested MRSA clinical isolates, with a dose-dependent activity resulting in the highest percentage of bacterial
growth inhibition (89.39%) at 2MIC concentration.
Conclusion: Overall, our data demonstrated the potential of some AMPs against MRSA isolates, such
as Citropin 1.1 and CA(1-7)M(2-9)NH2, that represents a promising area of development for different