Salmonella spp./Shigella spp. are common pathogens attributed to diarrhea. Here, we describe a high-throughput platform for the screening of Salmonella spp./Shigella spp. using real-time PCR combined with guided culture.
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Method Article
A High-throughput Platform for the Screening of Salmonella spp./Shigella spp.
In This Article
Summary
Abstract
Fecal-oral transmission of acute gastroenteritis occurs from time to time, especially when people who handled food and water are infected by Salmonella spp./Shigella spp. The gold standard method for the detection of Salmonella spp./Shigella spp. is direct culture but this is labor-intensive and time-consuming. Here, we describe a high-throughput platform for Salmonella spp./Shigella spp. screening, using real-time polymerase chain reaction (PCR) combined with guided culture. There are two major stages: real-time PCR and the guided culture. For the first stage (real-time PCR), we explain each step of the method: sample collection, pre-enrichment, DNA extraction and real-time PCR. If the real-time PCR result is positive, then the second stage (guided culture) is performed: selective culture, biochemical identification and serological characterization. We also illustrate representative results generated from it. The protocol described here would be a valuable platform for the rapid, specific, sensitive and high-throughput screening of Salmonella spp./Shigella spp.
Introduction
Diarrhea is still a common health issue with a high incidence rate globally1,2. Though the mortality is relatively low, some patients show various symptoms for weeks (such as loose and watery stools, an urgency to go to the bathroom), which make the socioeconomic impact very high3,4. More seriously, some patients may even develop irritable bowel syndrome if left untreated5. There are various kinds of bacteria, viruses and parasites that can cause diarrhea6. Salmonella spp./Shigella spp. ....
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Protocol
The protocol follows the guidelines set by the human research ethics committee of Zhuhai International Travel Healthcare Center. Please use standard sterile operation during the experiment.
1. Culture Media Composition and Preparation
- Prepare Nutrient Broth: Dissolve 1% peptone, 0.3% beef extract, 0.5% sodium chloride, 0.1% glucose in H2O, adjust pH to 7.5 and autoclave it in 121 °C for 15 min.
- Prepare Selenite Cystine medium: Dissolve 0.5% peptone, 0.4% lactose, 1%Na2HCO3, 0.4% sodium hydrogen selenite, 0.001% L-Cystine in H2O, adjust pH to 7.0 and boil it for 5 min.
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Results
The protocol was applied for the screening of Salmonella spp./Shigella spp. in anal stool samples from people who would handle food and water.
In the real-time PCR step, as shown in Figure 5A, there was a successful amplification in HEX channel, which meant that the mixed sample was positive for Salmonella spp. Then a further real-time PCR was conducted on.......
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Discussion
Since Salmonella spp./Shigella spp. are often associated with food poisoning and fecal-oral transmission of acute gastroenteritis28,29 and the routine method is either labor-intensive or time-consuming7, we describe a high-throughput platform for the Salmonella spp./Shigella spp. screening, using real-time PCR combined with guided culture.
There are several steps that need con.......
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Disclosures
The authors have nothing to disclose.
Acknowledgements
This work was supported by the Science and Technology Program of Zhuhai, China (grant number 20171009E030064), the Science and Technology Program of Guangdong, China (grant number 2015A020211004) and the Science and Technology Program of General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China (grant number 2016IK302, 2017IK224).
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| Tris | Sigma | 10708976001 | |
| EDTA | Sigma | 798681 | |
| NP40 | Sigma | 11332473001 | |
| ddH2O | Takara | 9012 | |
| PrimeSTAR HS (Premix) | Takara | R040Q | |
| Nutrient Broth | LandBridge | CM106 | |
| Nutrient agar | LandBridge | CM107 | |
| Selenite Cystine medium | LandBridge | CM225 | |
| XLD | LandBridge | CM219 | |
| MAC | LandBridge | CM908 | |
| Salmonella chromogenic agar | CHROMagar | SA130 | |
| Salmonella diagnostic serum | Tianrun | SAL60 | |
| Shigella diagnostic serum | Tianrun | SHI54 | |
| anal swab (collecting tube plus) | Huachenyang | ||
| slide | Mingsheng | 7102 | |
| micro-loop | Weierkang | W511 | |
| incubator | Jinghong | DNP-9082 | |
| autoclave | AUL | SS-325 | |
| dry bath | Jinghong | KB-20 | |
| automated microbial identification system | bioMérieux | VITEK2 | other equivalent system could be used |
| fluorescent real-time PCR machine | ThermoFisher | ABI7500 | other equivalent machine could be used |
References
- Roy, S. L., Scallan, E., Beach, M. J. The rate of acute gastrointestinal illness in developed countries. Journal of Water and Health. 4, Suppl 2 31-69 (2006).
- Wilking, H., et al. Acute gastrointestinal illness in adults in G....
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