Development and application of isothermal amplification methods for rapid detection of F4 fimbriae producing Escherichia coli

Increased sensitivity of enterotoxigenic Escherichia coli detection in stool samples using oligonucleotide immobilized-magnetic nanoparticles

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A rapid detection of ETEC DNA with high sensitivity and specificity.

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The combination between magnetic nanoparticles and molecular technique.

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100-folds increase of sensitivity compared with gold standard.

PCR detection of enterotoxigenic Escherichia-coli (ETEC) can be used directly on stool sample. However, it still has limitations due to presence of PCR inhibitors and interferences. This study, oligonucleotide primer specific to ETEC was immobilized onto MNPs and applied for separation and enrichment of ETEC-DNA from contaminants in stool after boiling. DNA separation efficiency was evaluated using conventional PCR and magneto-PCR-enzyme linked-gene-assay (MELGA). Due to high specificity of primer and efficiency of nanoparticles to bring down PCR inhibitors, DNA separation using primer-immobilized-MNPs exhibited 100-fold increase of sensitivity compared to that using simple boiling. Moreover, the sensitivities in stool were increased from 10⁸ to 10⁶ CFU/mL and 10⁴ to 10² CFU/mL when PCR products were detected by gel electrophoresis and MELGA, respectively. Results suggested that oligonucleotide-immobilized-MNPs combined with boiling DNA extraction method was successfully used to separate the DNA of ETEC in stool with high sensitivity using MELGA.