EN-ISO (International Standardisation Organisation) 6579-1
The internationally accepted horizontal method for the detection of Salmonella is described in EN-ISO 6579-1:2017 ‘Microbiology of the food chain - Horizontal method for the detection, enumeration and serotyping of Salmonella - Part 1: Detection of Salmonella spp.’
The scope of this document includes:
• products intended for human consumption and the feeding of animals;
• environmental samples in the area of food production and food handling;
• samples from the primary production stage such as animal faeces, dust, and swabs.
In March 2020 Amendment 1 to EN-ISO 6579-1 was published, entitled:
EN ISO 6579-1:2017/A1:2020 Microbiology of the food chain - Horizontal method for the detection, enumeration and serotyping of Salmonella - Part 1: Detection of Salmonella spp. AMENDMENT 1: Broader range of incubation temperatures, amendment to the status of Annex D, and correction of the composition of MSRV and SC.
The main amendments to EN ISO 6579-1 are the following:
• The temperature range for incubation of selective media has been extended from 37 °C ± 1 °C to 34 °C to 38 °C without further tolerance (like it already was for non-selective media). This amendment also resulted in an update of the flow schemes in Annex A.
• In Annex B (B.4) the composition of Modified semi-solid Rappaport-Vassiliadis (MSRV) agar was corrected when preparing it from individual ingredients. In the composition described in EN-ISO 6579-1:2017 the final concentration of MgCl2 in MSRV agar was not correct.
• The status of Annex D on detection of Salmonella Typhi and Salmonella Paratyphi was changed from normative to informative.
• A few corrections were included in Annex D, especially concerning the composition of selenite cystine medium (broth) in Annex D.3. In EN-ISO 6579-1:2017 it is indicated that 100 ml L-cystine solution (D.3.1.2) should be added to 1000 ml base medium, but this has to be only 10 ml.
Occasionally problems may occur when using the selective enrichment medium Modified semi-solid Rappaport Vassiliadis (MSRV) agar. Information on different causes of possible problems, as well as possible solutions have been published in the EURL (European Union Reference Laboratory)-Salmonella Newsletter Vol. 24 No. 3 (September 2018), page 9-10: [link]
Alternative methods
In many EU (Europese unie) legislation, EN-ISO 6579-1 is prescribed as the reference method for detection of Salmonella. In this EU legislation it is also indicated that alternative methods may be used if validated against the reference method. In Regulation (EC) 2073/2005 ‘on microbiological criteria for foodstuffs’ the following information on the use of alternative methods is given in Article 5 (consolidated version 2019):
The use of alternative analytical methods is acceptable provided they are:
• validated against the specific reference method provided for in Annex I in accordance with the protocol set out in standard EN-ISO 16140-2, and
• validated for the food category specified in the relevant microbiological criterion set in Annex I the compliance with which is verified by the food business operator, or validated for a broad range of food as referred to in EN-ISO 16140-2.
Proprietary methods may be used as alternative analytical methods, provided they are:
• validated, in accordance with the protocol set out in standard EN-ISO 16140-2, against the specific reference method provided for verifying compliance with the microbiological criteria laid down in Annex I, as provided for in the third subparagraph, and
• certified by an independent certification body.
The certification of the proprietary method shall:
• be subject, at least every 5 years, to reassessment through renewal procedures,
• show that the production process assurance of the manufacturer was evaluated, and
• include a summary of or a reference to the validation results of the proprietary method and a statement on the quality management of the production process of the method.
In Europe, the following organisations perform (independent) validations following the procedure of EN-ISO 16140-2 (‘Microbiology of the food chain – Method validation - Part 2: Protocol for the validation of alternative (proprietary) methods against a reference method’). Certificates of validated methods are available at the relevant websites:
MicroVal: https://microval.org/
AFNOR validation: https://nf-validation.afnor.org/en/
NordVal: https://www.nmkl.org/index.php/en/nordval