Check & Trace enables fast Salmonella serotyping based on DNA technology

All living organisms are defined by the nature of their genetic code. The last decades has seen a revolution of technologies to determine the complete genetic code of any organism. Likewise, methodologies have been developed that can use these genetic codes to uniquely identify individual organisms and discriminate it from near relatives. We have developed an innovative DNA fingerprinting technology, called “Check & Trace”
to detect and characterise any organism.

Check & Trace is a novel genetic test system to rapidly confirm and identify multiple Salmonella serotypes in a single test from a pure culture. We offer two solutions to our customers. Our product the Check & Trace Salmonella 1.0 based on microarray detection and our new Check & Trace Salmonella 2.0 based on real-time PCR. Our first product detects up to 300 serotypes and is supported by our tech team in case an undefined genetic code is found. Our new Check & Trace Salmonella 2.0 has a very simple “plug-and-play” workflow giving test results within two hours. It may detect 59 serotypes; the ones mostly encountered in food production area’s.

The principle of the Check&Trace Salmonella system is based on specific molecular recognition of DNA target sequences and subsequent amplification with universal primers.

The importance of
Salmonella testing

According to the EU One Health Zoonoses Report, Salmonella is the second most reported foodborne gastrointestinal infection in humans with over 52,000 confirmed cases in 2020.

Salmonella is widespread and difficult to manage
Salmonellosis is not an important disease in poultry. There are two types that cause disease (of the 2600), Gallinarum and Pullorum, but companies can manage these quite well. The problem is other Salmonella types that may cause disease in humans and that often originate from food, mostly fresh meat.

A complete eradication of Salmonella from poultry production is an incredibly difficult goal due to the large variety of serotypes and highly complex epidemiology of this microorganism. In addition:

The bacteria are widespread in nature and able to survive weeks or months
Salmonella may constantly be re-introduced in production area’s by contaminated feed, soil, transport systems and materials from other production area’s
Salmonella may also be attached for longer periods to surfaces and equipment
Animals will mostly carry Salmonella without any symptoms

The ability to manage Salmonella safely is complex and combines many different elements including biosecurity, diagnostics and vaccination protocols.

Salmonella identified, what next?
Once Salmonella is confirmed, there is an urgent need to identify the serotype. The chain (breeders, hatchery, grow-out and feed) must be interrogated to obtain and serotype the isolates to find the source of the contamination. The faster serotypes are identified, the sooner a treatment strategy can be shaped.

Cutting edge technology:

Serotyping through DNA sequence differences

Comparison of molecular typing and conventional serotyping

Standard phenotypical serotyping method

(White–Kauffmann–Le minor scheme)

Subjective results (based in manual interpretation)
Expertise and a lot of training required
Different tests and sera for different serovars needed
Dependent on the phenotypical expression of antigens
Time to result: 5-14 days

Check&Trace Salmonella

✓ Objective results, thanks to software results

✓ Simple training (1 a 2 days)

✓ Single test

✓ High sensitivity and specificity

✓ 30 targets of Salmonella genomes

✓ Results in hours

Standard protocols for detection of Salmonella are time-consuming taking several days to generate a final positive or negative test result. (ISO-6579/1). If positive for Salmonella many countries require further typing of Salmonella for epidemiological and health risk assessments. Traditionally this is done using serotyping for the somatic (O) lipopolysaccharide and flagellar (H) protein antigens (ISO-6579/3). However, Salmonellae are antigenically complex with over 2 400 serovars having various combinations of the 46 O-antigens and 85 H-antigens (3). So, once positive, further typing of a positive Salmonella may again take several days to complete requiring many O- and H-antisera for full typing.

DNA typing differs from serotyping. With serotyping the presence of antigens on the cell surface and flagella are detected. This is based on expression of genes located on two specific segments of the Salmonella genome. The CTS assay detects genetic variation at 21 loci scattered over the whole Salmonella genome: this generates specific Salmonella genotypes, also called Genovars. The CTS database links Genovars to a collection of well-characterized Salmonella Serovars.

With the CTS assay confirmation and typing of Salmonella can be performed in hours starting from bacteria from a XLD or Nutrient Agar (NA) plate. The presence of DNA target sequences for typing and confirmation are detected in parallel with various internal controls. CTS uses a quick and simple sample preparation process and minimizes operator intervention.