Research round-up: Viable organism detection and outbreak reporting via Twitter

By Joseph James Whitworth contact

- Last updated on GMT

Let us know what you are doing on food safety for a chance to be included in our monthly round-up. Send to joe.whitworth@wrbm.com
Let us know what you are doing on food safety for a chance to be included in our monthly round-up. Send to joe.whitworth@wrbm.com

Related tags: Foodborne illness, Salmonella, Bacteria

For the third time of 2017 we run the lab gauntlet and analyse the data that relates to food safety and quality research.

We start with Colorado State University chemists​ who have created a set of handheld tests that can detect the presence of water or foodborne pathogens.

Chuck Henry, professor and chair of the Department of Chemistry, and colleagues targeted fecal indicator bacteria (FIB).

Common techniques like immunoassays and polymerase chain reactions (PCR) can lead to false positives and require expensive equipment. The gold standard is a lab culture but this can take up to 48 hours.

Researchers made two types of tests that detect an enzyme associated with the FIB bacteria. The first is a small strip of paper treated with a substrate molecule that changes color when it contacts the bacterial enzyme - similar to a home pregnancy test.

The second test is electrochemical and consists of screen-printed carbon electrodes on transparent sheets, which indicate the same bacteria by being inserted into a reader. The setup is similar to a home glucometer.

The team ran tests of contaminated water, as well as water contaminated with E. coli and Enterococcus faecalis used to wash clean alfalfa sprouts. Both tests detected the harmful bacteria within four to 12 hours.

Now they are working on a Raspberry Pi-based system that could perform kinetic measurements to detect changes in the bacteria levels over time and transmit the information to a cloud platform.

Henry said the tests can't tell which bacteria are present, but they can detect the broad class of FIB usually responsible for foodborne illness outbreaks.

"At this point, it is accurate but not specific. This is the test that tells you that you need to do more tests."

Modified PCR sample prep

In the next work Tuskegee University researchers have been issued a US patent for detection of viable foodborne, biothreat pathogens and other infectious microbes using modified Polymerase Chain Reaction (PCR) sample preparation.

The project was funded by the National Center for Food Protection and Defense (NCFPD) also known as Food Protection and Defense Institute (FPDI).

Two commonly used techniques for detecting viable microorganisms are culture and nucleic acid-based techniques. The traditional culture-based test is time-consuming and some organisms are not easily culturable or may not even grow.

Dr Teshome Yehualaeshet, principal investigator in the research project, said the main drawback of PCR is it detects the DNA from dead and viable organisms.

However, the Tuskegee University researchers’ patent enables detection of only the viable organisms.

“During the sample preparation for PCR, we used a safe compound which will be ideal as a routine detection protocol for the presence of viable organisms.

“This invention will be mainly beneficial, but not limited, to the food industry to monitor biological decontamination, disinfection or the sanitization process.”

Next, the public and government authorities using Twitter​ could improve foodborne illness reporting and steps that follow, according to a study from the Brown School at Washington University.

Jenine Harris, associate professor, and colleagues partnered with the City of St. Louis Department of Health in October 2015 on the HealthMap Foodborne Dashboard developed at Boston Children’s Hospital.

“The dashboard technology has potential for improving foodborne illness reporting and can be implemented in other areas to improve response to public health issues such as suicidality, the spread of Zika virus, infection and hospital quality,” ​she said.

In the first seven months of the pilot study, they identified 193 tweets relevant to food poisoning and replied with a link to a form for reporting illness to the health department. Nearly 7 % resulted in a report submission.

Although about 23% of the US population uses Twitter, extending it to other social media could improve reporting among non-Twitter users.

In other work, Allura Red may be appropriate as a sensor or edible probe​ to monitor foods and pharmaceuticals, according to a study.

Researchers from Rutgers University, the University of Pennsylvania and the University of Massachusetts made the discovery while looking at identifying and characterizing molecules in foods or ingredients that might provide signals of quality, stability or safety.

Many molecules found in foods absorb ultraviolet or visible light and emit light as fluorescence.

Because fluorescence is sensitive to the local chemical and physical environment, this emitted light can “report” on properties of the food, the pH, polarity, or for Allura Red, local viscosity or thickness.

One food dye, Sunset Yellow, “only exhibits phosphorescence in viscous solution, so we wanted to examine others that tend to be non-fluorescent to see if they might fluoresce in viscous solutions​,” said Richard Ludescher, professor of food science in the School of Environmental and Biological Sciences at Rutgers.

All of the dyes tested - Tartrazine, Fast Green, Allura Red and others - showed properties sensitive to changes in viscosity.

The work highlights the potential of harnessing molecules already inside food to monitor their basic physical and chemical properties.

With optical sensing, such analysis could be achieved within seconds during manufacture.

Salmonella damages DNA and preventing norovirus

Next, some serotypes of Salmonella can have permanent repercussions by damaging DNA​, according to Cornell scientists.

Rachel Miller, a doctoral candidate in food science and Martin Wiedmann, the Gellert Family Professor in Food Safety, examined serotypes of Salmonella that encode for cytolethal distending toxin (S-CDT) a virulence component for serotype Typhi – the cause of typhoid fever.

Salmonella serotypes Javiana, Montevideo, Oranienburg and Mississippi also carry the genetic material that encodes S-CDT, the researchers found.

In human cells grown in the lab, Salmonella strains with S-CDT were found to lead to signatures that indicate presence of DNA damage.

“Think about possible DNA damage this way: We apply sunscreen to keep the sun from damaging our skin. If you don’t apply sunscreen, you can get a sunburn – and possibly develop skin problems later in life,”​ said Miller.

“While not the sun, Salmonella bacteria may work in a similar way. The more you expose your body’s cells to DNA damage, the more DNA damage that needs to be repaired, and there may one day be a chance that the DNA damage is not correctly repaired. We don’t really know right now the true permanent damage from these Salmonella infections​.”

Finally, we cover a study which looks at which prevention strategies​ work best in stopping the spread of norovirus in the retail food setting.

It revealed that ensuring all symptomatic food employees do not work if experiencing symptoms of vomiting and diarrhea, including a 24-hour period after the symptoms subside, as well as installing touchless faucets and doors, would reduce transmission.

The study showed customers were 226% more likely to get infected when symptomatic food workers did not stay home.

Prevention strategies that led to the smallest numbers of infected customers included full compliance with excluding ill food workers experiencing symptoms of vomiting and/or diarrhea, proper handwashing techniques, glove use, no food contact with bare hands and increased hand-washing efficiency.

Related topics: Food Safety & Quality

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