ISO/TS 6579-2:2012 食品および動物飼料の微生物学  —  サルモネラ菌の検出、列挙、血清型別のための水平法  —  パート2：小型化された最も可能性の高い数値手法による列挙 | ページ 2

Foreword

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• an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in an ISO working group and is accepted for publication if it is approved by more than 50 % of the members of the parent committee casting a vote;
• an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting a vote.

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ISO/TS 6579-2 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 9, Microbiology.

ISO 6579 consists of the following part, under the general title Microbiology of food and animal feed — Horizontal method for the detection, enumeration and serotyping of Salmonella:

• Part 2: Enumeration·by·a·miniaturized·most·probable·number·technique [Technical Specification]

Additional parts, dealing with a detection method and guidance for serotyping are planned. ISO 6579:2002 is to be withdrawn at a later date.

Introduction

The procedure described is based on the method reported in Reference.^[1]

The enumeration procedure described here concerns a miniaturized most probable number (MPN) technique. For this mini-MSRV (modified semi-solid Rappaport–Vassiliadis) MPN technique, the volume of primary dilution tested is less than the volume in the detection method specified in ISO 6579:2002 + Cor.1:2004 + Amd.1:2007.^[5] For this reason, the sensitivity of the mini-MSRV technique is lower than in these detection methods (Reference^[1]). The detection limit of the mini-MSRV method is approximately 1 cfu/g, but can vary according to Salmonella serovar and per matrix. For the previously mentioned detection methods, this is typically 1 cfu/25 g (0,04 cfu/g). For samples with (very) low numbers of Salmonella spp. (<1 cfu/g), it is possible that the mini-MSRV procedure is not sufficiently sensitive. If a quantitative result is requested for samples likely to contain such low numbers (and tested negative with this mini-MSRV technique, for example), it is advisable to enumerate with a “conventional” MPN technique (not miniaturized). For other samples, the mini-MSRV method can have an advantage over the conventional MPN technique because the performance of the miniaturized MPN technique can take less time and need fewer resources (due to small amounts).

WARNING — In order to safeguard the health of laboratory personnel, it is essential that tests for detecting Salmonella, are only undertaken in properly equipped laboratories, under the control of a skilled microbiologist, and that great care is taken in the disposal of all incubated materials.

Persons using this International Standard should be familiar with normal laboratory practice. This standard does not purport to address all of the safety aspects, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.

1 Scope

This part of ISO 6579 gives a method for the enumeration of Salmonella spp. present in:

• products intended for human consumption and for the feeding of animals;
• environmental samples in the area of food production and food handling;
• animal faeces;
• environmental samples from the primary production stage;

by calculation of the most probable number (MPN).

The method is based on miniaturization of the dilution, pre-enrichment and selective enrichment steps. The selective enrichment medium, modified semi-solid Rappaport–Vassiliadis (MSRV), is intended for the detection of motile salmonellae and is not appropriate for the detection of non-motile salmonellae.

It is possible that the method is less appropriate to enumerate Salmonella ser. Typhi and Salmonella ser. Paratyphi.

The method is not appropriate for the enumeration of Salmonella spp. in (very) low contaminated samples (<1 cfu/g).

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

Bibliography