Pathogen testing in finer detail

By Joseph James Whitworth contact

- Last updated on GMT

What is the future for pathogen testing?
What is the future for pathogen testing?
Food companies are looking at the finer details when it comes to pathogen testing, according to Thermo Fisher Scientific.

The firm said speed is important but from an industry perspective, accuracy is the absolute level of performance with what is at risk.

Customers realise that there is a trade- off between speed and accuracy to ensure that accuracy wins, it said.

Ravindra Ramadhar, Thermo Fisher food safety business director, told that firms want a broader type of information, which means expanded scope of pathogen testing.

“It has changed and there has been a broadening of the testing that food companies are doing. Regulated testing on pathogens or a chemical safety base was always there but now it is growing," ​he said.

“With Salmonella, Listeria monocytogenes testing the scope has widened for the serotypes and with E.coli it is not just O157 anymore.”

Keeping customers informed

Ramadhar said that across the industry testing is moving as informing customers and reassuring them of the truth in content and labelling is a pressing issue.

“A few years ago most companies just wanted to know if there was a presence or absence of Salmonella.

“Now there is a finer level of detail, firms are asking is it Salmonella type A or type B because type B is identified with my food type, so they can have a food safety management system in place to manage that.”

He said molecular methods brought speed, more time and specificity which was driving a move away from antibody-based methods based on proteins.

“Molecular methods can give you more information and discern more reliably what is in the sample.

“Next generation sequencing is used in human clinical diseases but understanding the pathogens and micro flora associated with foods will lead to better assay designs for food companies​.”

Testing methods

Outbreak teams look at specificity such as what is causing a strain outbreak situation and get access to information from genome sequencing which provides fast answers.

The US Centers for Disease Control and Prevention (CDC) used WGS for subtyping in the recent outbreak​ of Listeria linked to cheese from Roos Foods.

Ramadhar said WGS can quickly determine if a​n outbreak situation is affecting multiple locations or if the same strain is actually part of two independent events.

“PFGE is still the gold standard, as it has a wider history with 20 years in PulseNet but you can respond faster with WGS.

“You get PFGE patterns in a week and it requires a specialist where WGS doesn’t require a specialist, it is readily accessible and what comes out is digital information – it is this that provides the faster time.”

Industry was looking for more information to design or validate their food safety plan, said Ramadhar.

With a Salmonella screening assay you can check whether you have a Salmonella positive or not which covers all the serotypes. If you get a positive you can tell which serovar associated with which product type​.

“It is not regulation driven, the food industry is doing a better job of managing risk, it has matured with knowledge and in understanding management of food safety programmes.”

FSMA difference?

The Food Safety Modernization Act (FSMA) is one of the biggest changes in North America and has multiple ways to have an impact validation and verification, said Ramadhar.  

FSMA sets out the program to actively managing risk, it is responsible for verifying and validating performance of the program.

Ramadhar said that the legislation has caused other governments to look at their system – such as Canada and the Safe Food for Canadians Act and China has stepped up action.

He said added testing included meat identification and speciation based on fraud and authenticity, with food firms keen to show response as it affects their brand.

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