Vol.:(0123456789) 1 3 World Journal of Microbiology and Biotechnology (2020) 36:174 https://doi.org/10.1007/s11274-020-02948-6 ORIGINAL PAPER Anti-Staphylococcal and cytotoxic activities of the short anti-microbial peptide PVP Hamed Memariani 1  · Mojtaba Memariani 1  · Reza Mahmoud Robati 1,2  · Soheila Nasiri 1,2  · Fahimeh Abdollahimajd 1  · Zohre Baseri 3  · Hamideh Moravvej 1 Received: 23 June 2020 / Accepted: 8 October 2020 © Springer Nature B.V. 2020 Abstract Over the past years, short anti-microbial peptides have drawn growing attention in the research and trade literature because they are usually capable of killing a broad spectrum of pathogens by employing unique mechanisms of action. This study aimed to evaluate the anti-bacterial efects of a previously designed peptide named PVP towards the clinical strains of methi- cillin-resistant Staphylococcus aureus (MRSA) in vitro. Secondary structure, cytotoxicity, and membrane-permeabilizing efects of the peptide were also assessed. PVP had a tendency to adopt alpha-helical conformation based upon structural predictions and circular dichroism spectroscopy (in 50% trifuoroethanol). The peptide showed MIC values ranging from 1 to 16 µg/mL against 10 strains of MRSA. In contrast to ciprofoxacin and gentamicin, PVP at sub-lethal concentration (1 µg/ mL) did not provoke the development of peptide resistance after 14 serial passages. Remarkably, 1 h of exposure to 4 × MBC of PVP (8 µg/mL) was sufcient for total bacterial clearance, whereas 4 × MBC of vancomycin (8 µg/mL) failed to totally eradicate bacterial cells, even after 8 h. PVP showed negligible cytotoxicity against human dermal fbroblasts at concentra- tions required to kill the MRSA strains. The results of fow cytometric analysis and fuorescence microscopy revealed that PVP caused bacterial membrane permeabilization, eventually culminating in cell death. Owing to the potent anti-bacterial activity, fast bactericidal kinetics, and negligible cytotoxicity, PVP has the potential to be used as a candidate antibiotic for the topical treatment of MRSA infections. Keywords Anti-microbial peptide · Methicillin-resistant Staphylococcus aureus · Bactericidal activity · Human dermal fbroblasts · Membrane permeabilization Abbreviations AMPs Anti-microbial peptides AO/EtBr Acridine orange/ethidium bromide CD Circular dichroism CFUs Colony forming units DMEM Dulbecco’s Modifed Eagle’s Medium HDFs Human dermal fbroblasts MBC Minimum bactericidal concentration MDR Multidrug resistant MHB Müeller-Hinton broth MIC Minimum inhibitory concentration MRSA Methicillin-resistant Staphylococcus aureus PBS Phosphate-bufered saline PCR Polymerase chain reaction PI Propidium iodide RP-HPLC Reversed-phase high performance liquid chromatography SI Selectivity index SD Standard deviation TFE Trifuoroethanol TSB Tryptic soy broth * Mojtaba Memariani memaryani@gmail.com * Hamideh Moravvej hamidehmoravej@sbmu.ac.ir 1 Skin Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2 Department of Dermatology, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran 3 Department of Pathology and Laboratory Medicine, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran