title: Cell-penetrating peptide and antibiotic combination therapy: a potential alternative to combat drug resistance in methicillin-resistant Staphylococcus aureus.
abstract: The diverse pattern of resistance by methicillin-resistant Staphylococcus aureus (MRSA) is the major obstacle in the treatment of its infections. The key reason of resistance is the poor membrane permeability of drug molecules. Over the last decade, cell-penetrating peptides (CPPs) have emerged as efficient drug delivery vehicles and have been exploited to improve the intracellular delivery of numerous therapeutic molecules in preclinical studies. Therefore, to overcome the drug resistance, we have investigated for the first time the effects of two CPPs (P3 and P8) in combination with four antibiotics (viz. oxacillin, erythromycin, norfloxacin, and vancomycin) against MRSA strains. We found that both CPPs internalized into the MRSA efficiently at very low concentration (<10 μM) which was non-toxic to bacteria as well as mammalian cells and showed no significant hemolytic activity. However, the combinations of CPPs (≤10 μM) and antibiotics showed high toxicity against MRSA as compared to antibiotics alone. The significant finding is that P3 and P8 could lower the MICs against oxacillin, norfloxacin, and vancomycin to susceptible levels (generally <1 μg/mL) for almost all five clinical isolates. Further, the bacterial cell death was confirmed by scanning electron microscopy as well as propidium iodide uptake assay. Simultaneously, time-kill kinetics revealed the increased uptake of antibiotics. In summary, CPPs assist to restore the effectiveness of antibiotics at much lower concentration, eliminate the antibiotic toxicity, and represent the CPP-antibiotic combination therapy as a potential novel weapon to combat MRSA infections.
authors.affiliation: Bioactive Screening Laboratory, CSIR-Institute of Microbial Technology, Chandigarh, 160036, India.
authors.forename: Harmandeep Kaur
authors.initials: HK
authors.lastname: Randhawa
authors.affiliation: Bioinformatic Centre, CSIR-Institute of Microbial Technology, Chandigarh, 160036, India.
authors.forename: Ankur
authors.initials: A
authors.lastname: Gautam
authors.affiliation: Bioinformatic Centre, CSIR-Institute of Microbial Technology, Chandigarh, 160036, India.
authors.forename: Minakshi
authors.initials: M
authors.lastname: Sharma
authors.affiliation: Cell Biology and Immunology Laboratory, CSIR-Institute of Microbial Technology, Chandigarh, 160036, India.
authors.forename: Rakesh
authors.initials: R
authors.lastname: Bhatia
authors.affiliation: Cell Biology and Immunology Laboratory, CSIR-Institute of Microbial Technology, Chandigarh, 160036, India.
authors.forename: Grish C
authors.initials: GC
authors.lastname: Varshney
authors.affiliation: Bioinformatic Centre, CSIR-Institute of Microbial Technology, Chandigarh, 160036, India. raghava@imtech.res.in.
authors.forename: Gajendra Pal Singh
authors.initials: GP
authors.lastname: Raghava
authors.affiliation: Bioactive Screening Laboratory, CSIR-Institute of Microbial Technology, Chandigarh, 160036, India. hemraj@imtech.res.in.
authors.forename: Hemraj
authors.initials: H
authors.lastname: Nandanwar
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D057846:Cell-Penetrating Peptides / Q000494:pharmacology*; D004357:Drug Synergism; D005456:Fluorescent Dyes / Q000378:metabolism; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D011419:Propidium / Q000378:metabolism; D013194:Staining and Labeling
chemical_list: D000900:Anti-Bacterial Agents; D057846:Cell-Penetrating Peptides; D005456:Fluorescent Dyes; D011419:Propidium
keywords: Cell-penetrating peptides; Drug delivery; Drug resistance; Methicillin-resistant Staphylococcus aureus