Designing, Synthesis and In Vitro Antimicrobial Activity of Peptide Against Biofilm Forming Methicillin Resistant Staphylococcus aureus.

Increasing antimicrobial resistance and residue in an ecosystem is a huge threat to human as well as animal possibly inviting an uncontrollable outbreak and spoiling food. Use of alternative approaches in tackling the resistance problem has shown promising results in recent past. The present study was targeted to develop and evaluate the use synthetic peptide against biofilm forming methicillin resistant Staphylococcus aureus (MRSA). Peptide evaluation included determination of MIC, time kill kinetics, lysis activity, cell cytotoxicity assay, effect on biofilm formation, mechanism of action, thermo-stability and pH stability. Initially, a synthetic antimicrobial peptide, RWWKARIRL (ANLP-V3) was designed using bioinformatics tools and synthesized by solid phase synthesis using Fmoc chemistry. Peptide was found to exhibit antibacterial activity at 19.5 µg/mL concentration against both ATCC & clinical isolates of S. aureus. The time kill kinetic studies revealed > 99% inhibition of growth after 3 h at MIC, whereas 100% cell inhibition was seen at 2 h at 2 × MIC and 4 × MIC. No cytotoxicity was observed against mice RBCs as well as Vero cells at 2 × MIC. The AMP was found to be thermo-stable as well as pH stable at a wide range. Field emission scanning electron microscopy study demonstrates cell morphological alterations in AMP treated cells indicating membrane interacting nature of AMP. At MIC concentration, effective inhibition of biofilm formation in ATCC strains was seen. In conclusion, designed peptide might be effective antimicrobial agent against methicillin resistant biofilm forming S. aureus underlining possibilities of its preclinical development against mastitis in dairy animals.