Comparison of Three Rapid Diagnostic Assays for Diagnosis of Leptospirosis in A Resource Poor Setting

Abstract

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Nanom aterials-are possible alternatives to antibiotics due to minimal microbial resistance. Owing to high biocompatibility and antimicrobial properties, iron oxide nanoparticles (Fe30 4) have high potential for using as an antim icrobial agent and their superparamagnetic properties could allow targeted delivery inside the body with a magnetic field. Graphene oxide (GO} possess excellent biocompatible, chemical and mechanical properties and so is often used to support and stabilize nanoparticles for preparation of novel antibacterial nanocomposites. In this study, w e synthesized graphene oxide-iron oxide nanocomposite (GO-Fe) and compared antibacterial activity with GO and Fe30 4 on selected medically im portant bacteria. Fe30 4 was prepared using modified Massart method and GO-Fe synthesized via simple mixing after dispersing Fe30 4 in 1 M H N 03. The nano-characterization was carried out using UV-Visible spectroscopy, Ram an spectroscopy and Atomic force microscopy. The antibacterial activity was tested against Escherichia coli (ATCC-25922), Pseudomonas aeruginosa (ATCC-25853), Acinetobacter baumannii and Staphylococcus aureus (ATCC-25923). Absorbance at 630 nm of cultures treated w ith different concentrations of nanoparticles, 3.0 m g/m l to 23.4 /tg/m l, was m easured at 24 and 48 hours w ith appropriate controls in triplicate. Bacterial viability m easured using the Resazurine reduction assay at 24 and 48 hours. Fe30 4 were well deposited onto GO sheets, w ith an average size of 84± 9 nm. Percentage reduction of absorbance was directly correlated w ith the nanoparticle concentration. The GO-Fe nanocomposite resulted in the highest percentage reduction after 48 hours as 82.34% (E. coli), 84% (P. aeruginosa), 88.56% (S. aureus) and 82.55% (A. baumannii) at 3.0 m g/m l and it was significantly different from the percent reduction of GO and Fe30 4 nanoparticles. Antimicrobial activity based on bacterial viability was observed at concentrations above 375 /zg/ml for all nanoparticles tested for both time intervals. Further GO-Fe composite demonstrated a significantly high antimicrobial property for all bacterial species compared to GO and Fe30 4 nanoparticles (P<0.05). Our results indicate that the GO-Fe nanocomposite is a potential antibacterial agent 0.45) showed satisfactory agreement with MAT and PCR. False positives and false negatives were seen in all three kits