Detection of methicillin-resistant staphylococcus aureus using a gold nanoparticle-based colourimetric assay

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Detection of methicillin-resistant staphylococcus aureus using a gold nanoparticle-based colourimetric assay

 

Author: Chan, Wai Sing
Title: Detection of methicillin-resistant staphylococcus aureus using a gold nanoparticle-based colourimetric assay
Degree: D.H.Sc.
Year: 2013
Subject: Nanoparticles
Methicillin resistance
Staphylococcus aureus
Hong Kong Polytechnic University -- Dissertations
Department: Faculty of Health and Social Sciences
Pages: xiii, 94 leaves : color illustrations ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2760495
URI: http://theses.lib.polyu.edu.hk/handle/200/7627
Abstract: We report the use of gold nanoparticles (Au NPs) for direct colourimetric polymerase chain reaction (PCR) detection of methicillin-resistant Staphylococcus aureus (MRSA) in clinical specimens. The colourimetric assay comprised of two Au NP probes functionalized with Staphylococcus aureus 23S rRNA- and mecA-specific oligonucleotides. In this study, 72 clinical samples were tested, which included positive blood culture (n = 23), urine (n = 8), respiratory samples (n = 23), as well as wound swabs, pus and body fluid (n = 18). Results were recorded qualitatively by direct visual examination and quantitatively by UV-Vis spectrophotometry. Using conventional bacterial culture as the gold standard, the sensitivity, specificity, positive predictive value and negative predictive value of this colourimetric assay were 97.14%, 91.89%, 91.89% and 97.14%, respectively, which were comparable to that of commercial real-time PCR assays with a lower cost per reaction. Our assay also showed good agreement with bacterial culture ({469} = 0.889). The overall detection limit was 500 ng target amplicon, which was comparable to or better than other similar Au NP biosensors. Interestingly, our data revealed the possible relationship between Au NP probe-target hybridization site and assay performance, which might provide hints for design of the Au NP biosensors for nucleic acid detection. To conclude, our study was the first report on the use of Au NP colourimetric assay for direct detection of MRSA in various types of clinical specimens. Further evaluation of the assay is needed in large-scale trials which can also allow for some modifications to streamline the procedures for routine use.

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