Abstract

Shiga toxin-producing Escherichia coli serotype O157:H7 is a food and waterborne zoonotic pathogen causing gastroenteritis in humans. Rapid and simple detection in water and food is imperative to control its spread. However, traditional microbial detection approaches are time-consuming, expensive and complex to operate at the point-of-care without professional training. We present a rapid, simple, sensitive, specific and portable method for detection of E. coli O157:H7 in drinking water, apple juice and milk. We evaluated the effect of gene selection in detecting E. coli O157:H7 using recombinase polymerase amplification coupled with a lateral flow assay using rfbE, fliC and stx gene targets. As low as 100 ag and 1 fg DNA, 4–5 CFU/mL and 101 CFU/mL of E. coli O157:H7 was detected using the stx and rfbE gene targets respectively with 100% specificity, whilst the detection limit was 10 fg DNA and 102 CFU/mL for the fliC gene target, with 72.8% specificity. The RPA-LFA can be completed within 8 min at temperatures between 37 and 42 °C with reduced handling and simple equipment requirements. The test threshold amplification of the target was achieved in 5–30 min of incubation. In conclusion, RPA-LFA represents a potential rapid and effective alternative to conventional methods for the monitoring of E. coli O157:H7 in food and water.

Highlights

  • Shiga toxin-producing Escherichia coli serotype O157:H7 is a food and waterborne zoonotic pathogen causing gastroenteritis in humans

  • According to the World Health Organization (WHO), in 2005, 1.8 million people died from diarrheal diseases, traced to the consumption of food contaminated with pathogens including E. coli O157:H73

  • The Recombinase polymerase amplification (RPA)-AGE results confirmed the amplification of target E. coli O157:H7 with rfbE F1/R1, rfbE F2/R2, rfbE F3/R3, rfbE F4/R4, fliC F2/R2, fliC F3/R3, fliC F4/R4, Eco stx[2] F1/R1, Eco stx F2/R2 primer sets; no amplification was attained with fliC F1/R, stx[1] F1/R1 and stx[1] F2/R21

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Summary

Introduction

Shiga toxin-producing Escherichia coli serotype O157:H7 is a food and waterborne zoonotic pathogen causing gastroenteritis in humans. Molecular assays such as polymerase chain reaction (PCR)[6] and pulse field gel electrophoresis (PFGE)[7] have been developed for the identification of E. coli O157:H7 These methods overcome the limitation of culture based methods, having good sensitivity and specificity; these techniques require sophisticated devices, trained personnel and are generally expensive. Lateral flow (LF) paper-based microfluidics (LFPBM) is an emerging detection device that fulfils the criteria of an ideal POC diagnostic tool given by the World Health Organization (WHO) as ASSURED: Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free and ­Deliverable[10]. The principle of these LF devices is the capillary action of fluids through 3-dimensional porous microstructures. The specificity was found satisfactory and the detection limit was 1 × 1­ 04 CFU/mL, the complete assay takes 3–4 h and requires multiple antibodies, making the assay 3–4 times more expensive than traditional culture based and molecular ­methods[13]

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