SIST EN ISO 11290-2:2017/A1:2026

• Status: Published
• Public Enquiry End Date: 30-Jul-2025
• Publication Date: 19-Aug-2026
• ICS: 07.100.30 - Food microbiology
• Technical Committee: KŽP - Agricultural food products
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 30-Jul-2026
• Due Date: 04-Oct-2026
• Completion Date: 20-Aug-2026
• Ref Project: EN ISO 11290-2:2017/A1:2026 - Microbiology of the food chain - Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp. - Part 2: Enumeration method - Amendment 1: Inclusion of storage of the samples before analysis and changes in the control strain for performance testing of culture media and reagents (ISO 11290-2:2017/Amd 1:2026)

• Amends: SIST EN ISO 11290-2:2017 - Microbiology of the food chain - Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp. - Part 2: Enumeration method (ISO 11290-2:2017)
• Effective Date: 01-Sep-2026

SIST EN ISO 11290-2:2017/A1:2026 is a CEN amendment to the method for enumerating Listeria monocytogenes and Listeria spp. in the food chain. It updates EN ISO 11290-2:2017 with new provisions for storing samples before analysis and with revised control strains for performance testing of culture media and reagents. It is intended for laboratories and food-chain users that apply the enumeration method and verify the quality of their media and reagents.

What does SIST EN ISO 11290-2:2017/A1:2026 specify?

SIST EN ISO 11290-2:2017/A1:2026 specifies changes to the European adoption of ISO 11290-2:2017, not a standalone test method. The amendment focuses on sample handling before analysis, reference strains used in performance testing, and the wording in Annex B on quality assurance of culture media and reagents.

The document is organized as a short amendment with:

• a European foreword,
• a revised Clause 7 on sampling, transportation and storage of samples,
• revisions in 9.4.2.5.2 and 9.4.2.6 on the control strain,
• a rewritten B.2.8 in Annex B,
• added bibliography items [26] and [27].

What are the key requirements of SIST EN ISO 11290-2:2017/A1:2026?

Clause 7 keeps sampling outside the method itself and points users to the product-specific sampling standard where one exists. In practice, a laboratory must use the right sampling document for the product, because the enumeration result is only as representative as the sample it receives.

Clause 7 also adds storage guidance before analysis. Perishable food samples are to be kept refrigerated at 2 °C to 8 °C and examined immediately on receipt if possible, otherwise within less than 8 h; if they arrive late in the day, overnight storage is allowed and analysis should occur no later than 18 h after receipt, with the delay reported. If samples are stored between 1 °C and 5 °C, the time may be extended to 24 h without reporting the delay. For users, this means the sample handling log becomes part of the result record.

For samples that do not fit those conditions, the amendment allows alternative storage only when the parties agree or when it is shown that the contamination level of Listeria spp./Listeria monocytogenes is not affected. That matters because the test report then needs to justify the chosen conditions.

Clause 7 points users to specific sampling and storage standards:

• ISO/TS 17728 for food and animal feed,
• ISO 707 for milk and milk products,
• ISO 18593 for surfaces,
• ISO 7218 for storage of stable and surface samples,
• ISO 20976-1 for shelf-life studies.

In 9.4.2.5.2 and 9.4.2.6, the amendment replaces Listeria monocytogenes WDCM 00109 with Listeria monocytogenes WDCM 00231. In practice, laboratories must update the reference strain they use when checking media and reagent performance.

Annex B.2.8 now points users to ISO 11133 for the definitions of productivity, specificity and selectivity and for the general performance-testing procedure. This matters because media qualification is tied to a recognized quality-assurance framework rather than ad hoc checks.

Tables B.1 and B.2 still drive the actual quality checks for enumeration media and confirmation tests. They tell the user which control reactions to verify for productivity, selectivity, specificity, catalase, motility, Gram staining, haemolysis, CAMP reaction, carbohydrate utilization and Voges-Proskauer testing.

What terms does SIST EN ISO 11290-2:2017/A1:2026 define?

• Listeria monocytogenes - the target species that the enumeration method is designed to quantify.
• Listeria spp. - the broader group of Listeria species covered by the method.
• WDCM - the strain catalogue number used to identify the control strains named in the tables.
• Control strain - the reference organism used to check whether a medium or reagent gives the expected reaction.
• ISO 11133 - the standard that sets the performance-testing approach for culture media and reagents.
• TSA - tryptic soy agar, used in the productivity check in Annex B.
• TSYEA - the medium used for confirmation tests in Annex B.
• CAMP reaction - a haemolysis-based test used in the confirmation testing tables.

Who uses SIST EN ISO 11290-2:2017/A1:2026?

Food microbiology laboratories use SIST EN ISO 11290-2:2017/A1:2026 when they enumerate Listeria monocytogenes and Listeria spp. in food, milk, surfaces or other food-chain samples. Quality managers use it to set sample reception rules, decide storage limits before testing, and document deviations.

Manufacturers of culture media and reagents use the amendment when they verify product performance against the control strains in Annex B. Buyers, auditors and regulators use it as a reference for whether the laboratory’s sample handling and media controls match the European method.

What changed in SIST EN ISO 11290-2:2017/A1:2026 from the previous edition?

SIST EN ISO 11290-2:2017/A1:2026 amends EN ISO 11290-2:2017 and adopts ISO 11290-2:2017/Amd 1:2026 without modification. The stated changes are:

• added storage guidance for samples before analysis,
• replaced Listeria monocytogenes WDCM 00109 with WDCM 00231 in the performance-testing text,
• updated Annex B.2.8 on performance testing of culture media and reagents.

Which standards are used with SIST EN ISO 11290-2:2017/A1:2026?

• ISO/TS 17728 - recommended sampling techniques for food and animal feed.
• ISO 707 | IDF 50 - sampling guidance for milk and milk products.
• ISO 18593 - sampling of surfaces.
• ISO 7218 - storage conditions for stable samples, frozen samples and surface samples.
• ISO 20976-1 - shelf-life studies of food and feed products.
• ISO 11133 - definitions and procedures for performance testing of culture media and reagents.

What does the SIST EN ISO 11290-2:2017/A1:2026 document contain?

The amendment contains the European foreword and the text changes that update the parent standard. Its main technical content is the revised sample storage clause, the revised control-strain references, and the rewritten Annex B.2.8 on quality assurance of culture media and reagents.

Annex B includes the performance-testing tables for enumeration media and for confirmation tests. Those tables are used in laboratory quality control and media verification, and they list the expected reactions for the named reference strains rather than the full test theory. The bibliography additions point users to the sampling guidance and to the standard for challenge tests and shelf-life work.

SLOVENSKI STANDARD
01-september-2026
Mikrobiologija v prehranski verigi - Horizontalna metoda za ugotavljanje
prisotnosti in števila Listeria monocytogenes in Listeria spp. - 2. del: Metoda štetja
- Dopolnilo A1: Vključitev shranjevanja vzorcev pred analizo in sprememb
kontrolnega seva za preskušanje učinkovitosti gojišč in reagentov (ISO 11290-
2:2017/Amd 1:2026)
Microbiology of the food chain - Horizontal method for the detection and enumeration of
Listeria monocytogenes and of Listeria spp. - Part 2: Enumeration method - Amendment
1: Inclusion of storage of the samples before analysis and changes in the control strain
for performance testing of culture media and reagents (ISO 11290-2:2017/Amd 1:2026)
Mikrobiologie der Lebensmittelkette - Horizontales Verfahren für den Nachweis und die
Zählung von Listeria monocytogenes und von Listeria spp. - Teil 2: Zählverfahren -
Änderung 1: Aufnahme der Lagerung der Proben vor der Analyse und Änderungen des
Kontrollstamms für die Leistungsprüfung von Kulturmedien und Reagenzien (ISO 11290-
2:2017/Amd 1:2026)
Microbiologie de la chaîne alimentaire - Méthode horizontale pour la recherche et le
dénombrement de Listeria monocytogenes et de Listeria spp. - Partie 2: Méthode de
dénombrement - Amendement 1: Inclusion du stockage des échantillons avant l'analyse
et les modifications dans la souche témoin pour les essais de performance des milieux
de culture et des réactifs (ISO 11290-2:2017/Amd 1:2026)
Ta slovenski standard je istoveten z: EN ISO 11290-2:2017/A1:2026
ICS:
07.100.30 Mikrobiologija živil Food microbiology
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 11290-2:2017/A1
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2026
EUROPÄISCHE NORM
ICS 07.100.30
English Version
Microbiology of the food chain - Horizontal method for the
detection and enumeration of Listeria monocytogenes and
of Listeria spp. - Part 2: Enumeration method -
Amendment 1: Inclusion of storage of the samples before
analysis and changes in the control strain for performance
testing of culture media and reagents (ISO 11290-
2:2017/Amd 1:2026)
Microbiologie de la chaîne alimentaire - Méthode Mikrobiologie der Lebensmittelkette - Horizontales
horizontale pour la recherche et le dénombrement de Verfahren für den Nachweis und die Zählung von
Listeria monocytogenes et de Listeria spp. - Partie 2: Listeria monocytogenes und von Listeria spp. - Teil 2:
Méthode de dénombrement - Amendement 1: Inclusion Zählverfahren - Änderung 1: Aufnahme der Lagerung
du stockage des échantillons avant l'analyse et les der Proben vor der Analyse und Änderungen des
modifications dans la souche témoin pour les essais de Kontrollstamms für die Leistungsprüfung von
performance des milieux de culture et des réactifs (ISO Kulturmedien und Reagenzien (ISO 11290
11290-2:2017/Amd 1:2026) 2:2017/Amd 1:2026)
This amendment A1 modifies the European Standard EN ISO 11290-2:2017; it was approved by CEN on 1 July 2026.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for inclusion of
this amendment into the relevant national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This amendment exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11290-2:2017/A1:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 11290-2:2017/A1:2026) has been prepared by Technical Committee ISO/TC 34
"Food products" in collaboration with Technical Committee CEN/TC 463 “Microbiology of the food
chain” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2027, and conflicting national standards shall
be withdrawn at the latest by January 2027.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 11290-2:2017/Amd 1:2026 has been approved by CEN as EN ISO 11290-
2:2017/A1:2026 without any modification.

International
Standard
ISO 11290-2
Second edition
Microbiology of the food chain —
2017-05
Horizontal method for the detection
and enumeration of Listeria
AMENDMENT 1
monocytogenes and of Listeria
2026-07
spp. —
Part 2:
Enumeration method
AMENDMENT 1: Inclusion of storage
of the samples before analysis and
changes in the control strain for
performance testing of culture media
and reagents
Microbiologie de la chaîne alimentaire — Méthode
horizontale pour la recherche et le dénombrement de Listeria
monocytogenes et de Listeria spp. —
Partie 2: Méthode de dénombrement
AMENDEMENT 1: Inclusion du stockage des échantillons avant
l'analyse et modifications dans la souche témoin pour les essais
de performance des milieux de culture et des réactifs
Reference number
ISO 11290-2:2017/Amd.1:2026(en) © ISO 2026

ISO 11290-2:2017/Amd.1:2026(en)
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ISO copyright office
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 11290-2:2017/Amd.1:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO’s adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 9,
Microbiology, in collaboration with the European Committee for Standardization (CEN) Technical Committee
CEN/TC 463, Microbiology of the food chain, in accordance with the Agreement on technical cooperation
between ISO and CEN (Vienna Agreement).
A list of all parts in the ISO 11290 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iii
ISO 11290-2:2017/Amd.1:2026(en)
Microbiology of the food chain — Horizontal method for the
detection and enumeration of Listeria monocytogenes and of
Listeria spp. —
Part 2:
Enumeration method
AMENDMENT 1: Inclusion of storage of the samples before
analysis and changes in the control strain for performance testing
of culture media and reagents
Clause 7
Replace the text with the following:
7  Sampling, transportation and storage of samples
Sampling is not part of the method specified in this document. Follow the specific International Standard
dealing with the product concerned. If there is no specific International Standard dealing with the sampling
of the product concerned, it is recommended that the parties concerned come to an agreement on this
subject. Recommended sampling techniques are given in the following documents:
[22]
— ISO/TS 17728 for food and animal feed;
[26]
— ISO 707 for milk and milk products;
[1]
— ISO 18593 for surfaces (see also see Reference [23]).
It is important that the laboratory receives a sample which is representative of the product under
consideration. The sample should not have been damaged or changed during transport or storage.
[27]
NOTE 1 Shelf-life studies are not in the scope of this document but of ISO 20976-1 .
For storage conditions for stable samples (e.g. non-perishable or low-moisture foods samples) as well as
frozen or deep-frozen products before analysis, see ISO 7218. For storage conditions for surface samples,
[1]
see ISO 7218 and ISO 18593 .
Before analysis, store perishable food samples refrigerated at 2 °C to 8 °C. Examine the samples immediately
upon receipt if possible, and if not possible, within a delay less than 8 h. In case of late arrival of samples in
the working day, samples may be stored overnight and should be analysed no later than 18 h after receipt.
In this case, the delay should be reported in the test report. However, if samples are stored between 1 °C and
5 °C, the duration may be extended up to 24 h after receipt, without the necessity to include the delay in the
test report.
If these conditions cannot be applied, other storage conditions may be used provided it can be demonstrated
that the alternative conditions do not affect the contamination levels of Listeria spp./Listeria monocytogenes
or agreed between parties concerned. These conditions should be detailed and justified in the test report.
NOTE 2 Supporting data for storage of food samples before detection of Listeria monocytogenes or Listeria spp. are
available from: https:// standards .iso .org/ iso/ 11290/ -2/ ed -2/ en/ amd/ 1.

ISO 11290-2:2017/Amd.1:2026(en)

9.4.2.5.2 and 9.4.2.6
Replace all instances of Listeria monocytogenes WDCM 00109 with Listeria monocytogenes WDCM 00231.
...