title: Polyethylene glycol-stabilized sulphur nanoparticles: an effective antimicrobial agent against multidrug-resistant bacteria.
abstract: OBJECTIVE
  To elucidate the antibacterial efficacy of chemically synthesized and custom-made sulphur nanoparticles (SNPs) of two different sizes and surface modifications against a number of multidrug-resistant Gram-negative bacilli (GNB) harbouring the New Delhi metallo-β-lactamase 1 enzyme (NDM-1).
  
  
  METHODS
  Antimicrobial susceptibility of the isolates was determined. The strains were evaluated for the presence of carbapenemases, β-lactamases, 16S rRNA methylases and integrons. Chemically synthesized, polyethylene-glycol (PEG)-stabilized SNPs of 10 nm and custom-made non-capped SNPs of 60 nm were physicochemically characterized and evaluated for their antibacterial efficacy against multidrug-resistant GNB using the agar dilution method (ADM) and the broth microdilution method (BMD). The cytotoxicity of the chemically synthesized SNPs was evaluated with a human-derived hepatoma (HepG2) cell line using a WST-1 assay kit.
  
  
  RESULTS
  All isolates were multidrug-resistant and possessed NDM-1 along with other β-lactamases, 16S rRNA methylases and integron 1. Chemically synthesized PEGylated SNPs showed a bactericidal effect against all tested strains at a concentration between 9.41 and 18.82 mg/L using BMD. The ADM data revealed that SNPs had uniform MICs (18.82 mg/L) for all tested strains. On the other hand, custom-made SNPs failed to impart any antibacterial effect at the equivalent concentrations of chemically synthesized SNPs. The WST-1 assay revealed no significant cytotoxicity of the PEGylated SNPs even at the highest concentration (94.08 mg/L).
  
  
  CONCLUSIONS
  To the best of our knowledge, this is the first attempted study to show the effectiveness of nanoparticles against multidrug-resistant GNB harbouring NDM-1.
authors.affiliation: Biological Sciences Division, Indian Statistical Institute, Kolkata, India.
authors.forename: Samrat Roy
authors.initials: SR
authors.lastname: Choudhury
authors.forename: Subhasree
authors.initials: S
authors.lastname: Roy
authors.forename: Arunava
authors.initials: A
authors.lastname: Goswami
authors.forename: Sulagna
authors.initials: S
authors.lastname: Basu
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D024901:Drug Resistance, Multiple, Bacterial; D005798:Genes, Bacterial; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000201:enzymology; D022781:Hepatocytes / Q000187:drug effects; D006801:Humans; D008826:Microbial Sensitivity Tests; D053758:Nanoparticles / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000494:pharmacology* / Q000633:toxicity; D013455:Sulfur / Q000494:pharmacology* / Q000633:toxicity; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D000890:Anti-Infective Agents; D011092:Polyethylene Glycols; D013455:Sulfur; D001618:beta-Lactamases; C552864:beta-lactamase NDM-1