Micreos positive on EFSA Listex opinion

By Joseph James Whitworth

- Last updated on GMT


Related tags Listeria Listeria monocytogenes European food safety authority

Micreos has said it is ‘very positive’ following a European Food Safety Authority (EFSA) opinion on its technology for Listeria monocytogenes in Ready to Eat (RTE) foods.

Safety and efficacy of Listex P100 used during processing of meat and poultry, fish and shellfish and dairy products was assessed.

Reduction of Listeria monocytogenes in artificially inoculated samples of the three RTE food categories was demonstrated after treatment and during storage, said EFSA (the opinion can be found here​).

It depends on the P100 dose applied with a best estimates ranging from 1.7 to 3.4 log10​ colony forming units (CFU) at the maximum dose.

The best time of application is just after post-lethal treatment or during the packaging process.

Concentration and log reduction

Bert de Vegt, managing director, said the recommendations are not unexpected.

“EFSA concludes that based on the evaluated studies, for all three RTE food categories (fish, meat and dairy) L. monocytogenes was reduced up to 3 log when applied at 5% concentration on the surface of the food products,” ​he told FoodQualityNews. 

“For this EFSA used the PROMETHEUS methodology (Promoting Methods for Evidence Use in Scientific assessments) concluding that Listex is not only safe but effective as well​.” 

He said EFSA recognizes the difficulty to validate applications under the guidelines in factories.

“EFSA says that there is huge benefit in reducing Listeria at the source and expects less contaminated products to reach the marketplace. Validating applications with food producers was also recommended and since this is part of the sales process we will continue to do so.” 

EFSA said experimental studies provided by Micreos and others indicate that between 2.5% and 9.5% of naturally occurring Listeria strains exhibit resistance to P100.

As far as the resistance issue the firm said it was not overly worried.

“We started selling Listex in 2005 and never have come across resistance. Resistance does not occur because of the presence of phages,” ​said de Vegt.

“If it occurs it occurs spontaneously in nature at a rate of one in 1-10 million. Almost always contamination levels in the factory are less than 10 cfu per gram. The chance that Listeria contamination was caused by a resistant strain is therefore very limited.”

Bert de Vegt added he hoped the Commission would move forward swiftly and approve Listex.

BIOHAZ panel opinion

Listex P100 contains bacteriophage P100 at a concentration of 2 × 1011​ plaque forming units (PFU) per mL.

Approval was sought for spraying or dipping treatments (or use in smear suspension for smeared cheese) using up to 1 × 109​ PFU of P100 per gram of product.

All except one of the 33 experiments were performed using artificially contaminated RTE foods.

L. monocytogenes at 100–10,000 CFU/g is not eliminated by Listex P100 in doses 108​–109​ PFU/cm2​ and growth may occur after treatment, found the BIOHAZ panel.

Listex P100 should be considered as an additional tool, to further reduce the load of L. monocytogenes, following Good Hygienic Practices (GHP) and Good Manufacturing Practices (GMP), and not as a substitute for them, it added.

Once Listex P100 is applied to the foodstuff surface, half an hour is needed for the bacteriophages to find their Listeria host bacteria and kill them. Exposure time depends on the shelf-life.

The EFSA panel said more studies on the efficacy of Listex P100 in naturally contaminated RTE foods should be undertaken.

“If Listex P100 is authorised and used, the FBO should validate the efficacy of the P100 dose applied in the specific product before it leaves the processing plant and, on a regular basis, examine the susceptibility to Listex P100 of L. monocytogenes​ strains isolated from the raw material/processing plant to Listex P100 and if resistant strains occur consider corrective actions.”

The latest work is based on an application for approval received last year.

The European Commission also received an application in 2011 from the company for the approval of Listex P100 to remove Listeria monocytogenes surface contamination in raw fish.

EFSA did a scientific opinion in 2012 on Listex P100 but the Commission said it had not taken legislative action, as the opinion left uncertainties concerning effectiveness in fishery products.

“However, to date, this substance has not been approved by the Commission because of insufficient scientific data to demonstrate the effectiveness of Listex P100 in fishery products which does not allow EFSA to draw definitive conclusions,” ​said the European Commission. 

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