title: Antimicrobial potentials of Helicteres isora silver nanoparticles against extensively drug-resistant (XDR) clinical isolates of Pseudomonas aeruginosa.
abstract: Pseudomonas aeruginosa is a leading opportunistic pathogen and its expanding drug resistance is a growing menace to public health. Its ubiquitous nature and multiple resistance mechanisms make it a difficult target for antimicrobial chemotherapy and require a fresh approach for developing new antimicrobial agents against it. The broad-spectrum antibacterial effects of silver nanoparticles (SNPs) make them an excellent candidate for use in the medical field. However, attempts made to check their potency against extensively drug-resistant (XDR) microbes are meager. This study describes the biosynthesis and biostabilization of SNPs by Helicteres isora aqueous fruit extract and their characterization by ultraviolet-visible spectroscopy, transmission electron microscopy, dynamic light scattering, X-ray diffraction, and Fourier transform infrared spectroscopy. Majority of SNPs synthesized were of 8--20-nm size. SNPs exhibited dose-dependent antibacterial activities against four XDR P. aeruginosa (XDR-PA) clinical isolates as revealed by growth curves, with a minimum inhibitory concentration of 300 μg/ml. The SNPs exhibited antimicrobial activity against all strains, with maximum zone of inhibition (16.4 mm) in XRD-PA-2 at 1000 μg/ml. Amongst four strains, their susceptibilities to SNPs were in the following order: XDR-PA-2 > XDR-PA-4 > XDR-PA-3 > XDR-PA-1. The exposure of bacterial cells to 300 μg/ml SNPs resulted into a substantial leakage of reducing sugars and proteins, inactivation of respiratory chain dehydrogenases, and eventual cell death. SNPs also induced lipid peroxidation, a possible underlying factor to membrane porosity. The effects were more pronounced in XDR-PA-2 which may be correlated with its higher susceptibility to SNPs. These results are indicative of SNP-induced turbulence of membranous permeability as an important causal factor in XDR-PA growth inhibition and death.
authors.affiliation: Department of Biotechnology, Modern College of Arts, Science and Commerce, S. P. Pune University, Ganeshkhind, Pune, 411 016, India.
authors.forename: Nikunj
authors.initials: N
authors.lastname: Mapara
authors.affiliation: Department of Biotechnology, Modern College of Arts, Science and Commerce, S. P. Pune University, Ganeshkhind, Pune, 411 016, India.
authors.forename: Mansi
authors.initials: M
authors.lastname: Sharma
authors.affiliation: Department of Botany, Prof. Ramkrishna More Arts, Commerce and Science College, S. P. Pune University, Akurdi, Pune, 411044, India.
authors.forename: Varsha
authors.initials: V
authors.lastname: Shriram
authors.affiliation: Department of Microbiology, B. J. Government Medical College, Pune, 411001, India.
authors.forename: Renu
authors.initials: R
authors.lastname: Bharadwaj
authors.affiliation: School of Energy Studies, Department of Physics, Savitribai Phule Pune University, Ganeshkhind, Pune, 411007, India.
authors.forename: K C
authors.initials: KC
authors.lastname: Mohite
authors.affiliation: Department of Biotechnology, Modern College of Arts, Science and Commerce, S. P. Pune University, Ganeshkhind, Pune, 411 016, India. vinaymalik123@gmail.com.
authors.forename: Vinay
authors.initials: V
authors.lastname: Kumar
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D019660:Malvaceae / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D012834:Silver / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D013057:Spectrum Analysis
chemical_list: D000890:Anti-Infective Agents; D010936:Plant Extracts; D012834:Silver
keywords: Antimicrobial agents; Bacterial membrane; Extensively drug resistant (XDR); Helicteres isora; Pseudomonas aeruginosa; Silver nanoparticles