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ISO 7218:2024(en)
ISO - Cover page
Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Premises
 4.1 General
 4.2 Biosafety considerations
 4.3 Laboratory design
 4.4 Laboratory areas
  4.4.1 General
  4.4.2 Areas associated with samples and testing
  4.4.3 General areas
 4.5 Layout and fittings of the premises
  4.5.1 Objectives
  4.5.2 Fittings
  4.5.3 Other arrangements for laboratory premises
  4.5.4 Cleaning and disinfection
5 Personnel
 5.1 General
 5.2 Competence
 5.3 Verification of ongoing staff competence
 5.4 Hygiene
6 Equipment and consumables
 6.1 General
 6.2 Sterilization and other heating equipment
  6.2.1 General
  6.2.2 Autoclave
  6.2.3 Culture media preparator
  6.2.4 Steamers, including boiling-water baths
  6.2.5 Sterilizing oven
  6.2.6 Microwave oven
  6.2.7 Hotplate, induction cooker and heating mantle
  6.2.8 Gas burner or wire incinerator
 6.3 Temperature controlled equipment and monitoring devices
  6.3.1 General
  6.3.2 Incubator
  6.3.3 Thermostatically controlled bath
  6.3.4 Heating blocks
  6.3.5 Refrigerators and cold-storage rooms
  6.3.6 Freezer and deep freezer/ultra-low temperature freezer
  6.3.7 Temperature-monitoring devices, including automatic recorders
  6.3.8 Balances and gravimetric diluters
 6.4 Defined volume inoculation equipment
  6.4.1 Pipettes and pipettors
  6.4.2 Dispensers
  6.4.3 Spiral platers
  6.4.4 Serial diluters
 6.5 Protective cabinets
  6.5.1 Description
  6.5.2 Use
  6.5.3 Cleaning and disinfection
  6.5.4 Maintenance and inspection
 6.6 Homogenizers, blenders, mixers and shakers
  6.6.1 Homogenizers and blenders
  6.6.2 Vortex mixers
 6.7 Stills, deionizers and reverse-osmosis units
  6.7.1 Description
  6.7.2 Use
  6.7.3 Maintenance
  6.7.4 Verification
 6.8 Separation and concentration equipment
  6.8.1 Immunomagnetic separator (IMS)
  6.8.2 Centrifuge
  6.8.3 Filtration systems
 6.9 Modified atmosphere equipment
  6.9.1 Description
  6.9.2 Use
  6.9.3 Maintenance
  6.9.4 Verification
 6.10 Other equipment
  6.10.1 pH meter
  6.10.2 Colony-counting device
  6.10.3 Timers and timing devices
  6.10.4 Optical microscope
  6.10.5 Glass washers, glassware and other laboratory ware
  6.10.6 Disposable equipment and consumables
  6.10.7 Other equipment and software
7 Sterilization/decontamination and disposal of laboratory materials
 7.1 Sterilization
  7.1.1 General
  7.1.2 Sterilization by dry heat
  7.1.3 Sterilization by moist heat (steam)
 7.2 Decontamination and disinfection
  7.2.1 Decontamination of glassware and materials before use
  7.2.2 Decontamination of glassware and materials after use
 7.3 Waste management
 7.4 Washing
8 Preparation and use of culture media and reagents
9 Laboratory samples
 9.1 Sampling techniques and sampling plans
  9.1.1 General
  9.1.2 Sampling
 9.2 Sample transport
 9.3 Sample receipt
 9.4 Sample handling
  9.4.1 General
  9.4.2 Storage before examination
  9.4.3 Test portions
  9.4.4 Storage of laboratory samples after examination
 9.5 Pre-testing of samples
10 Examination
 10.1 Hygienic precautions during sample preparation and examination
  10.1.1 General
  10.1.2 Basic precautions
  10.1.3 Sample handling
  10.1.4 Sample handling tools and implements
  10.1.5 Spillages
  10.1.6 Process controls
  10.1.7 Aerosols
  10.1.8 Molecular methods
 10.2 Preparation of initial suspension and dilutions
  10.2.1 General
  10.2.2 Concentration
11 Enumeration (quantitative) methods
 11.1 General
 11.2 Enumeration using a solid medium
  11.2.1 General
  11.2.2 Pour plate technique
  11.2.3 Surface plating techniques
  11.2.4 Enumeration of yeasts and moulds
  11.2.5 Incubation
  11.2.6 Calculation and expression of results obtained with solid culture media
  11.2.7 Calculations for enumeration methods
 11.3 Enumeration using liquid media
  11.3.1 Principle
  11.3.2 General MPN procedure
  11.3.3 Limitations of MPN
  11.3.4 Inoculation procedure
  11.3.5 Choice of MPN configuration
  11.3.6 Incubation
  11.3.7 Interpretation and expression of results
  11.3.8 Determination of MPN values using MPN calculators
  11.3.9 Rarity categories
 11.4 Estimates of uncertainty of test results
12 Detection (qualitative) methods
 12.1 General
 12.2 Principle
13 Confirmation and identification methods
 13.1 General
 13.2 Preparation of a pure culture
 13.3 Confirmation methods
  13.3.1 Latex agglutination test
  13.3.2 Nucleic acid hybridization or molecular amplification methods
  13.3.3 Slide agglutination tests
 13.4 Identification methods
  13.4.1 Biochemical galleries
  13.4.2 DNA sequencing
  13.4.3 Mass spectrometry
14 Selection and characterization of control microorganisms
 14.1 General
 14.2 Characterization of microorganisms
  14.2.1 General
  14.2.2 Phenotypic characterization
  14.2.3 Molecular characterization
 14.3 Selection of control microorganisms
15 Test report
16 Laboratory quality control in microbiology
 16.1 General
 16.2 Internal quality control
  16.2.1 General
  16.2.2 Process controls
  16.2.3 Replicate testing
  16.2.4 Spiked samples
  16.2.5 IQC assessment using control charts
 16.3 External quality assessment
17 Validation and verification of microbiological methods
 17.1 General
 17.2 Performance characteristics
 17.3 Validation
 17.4 Verification
Annex A (informative) Properties of disinfectants
Annex B (informative) Confidence intervals for colony count technique
Annex C (normative) General confirmation tests
Bibliography
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International

Standard

ISO 7218
Microbiology of the food chain — General requirements and guidance for microbiological examinations
Microbiologie de la chaîne alimentaire — Exigences générales et recommandations pour les examens microbiologiques
Reference number
ISO 7218:2024(en)
Fourth edition
2024-06
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ContentsPage

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 documents 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).
This fourth edition cancels and replaces the third edition (ISO 7218:2007), which has been technically revised. It also incorporates the Amendment ISO 7218:2007/Amd 1:2013.
The main changes are as follows:
the calculations section has been simplified and two further calculators have been added;
the equipment section has been reorganized into groups with similar purposes and requirements;
cross-references have been added to other general microbiology standards such as those for media, validation and verification, and uncertainty to reduce repetition;
information on laboratory quality control and characterization of control microorganisms has been added.
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.

Introduction

When conducting microbiological examinations, it is especially important that:
only those microorganisms present in the samples are detected and/or enumerated;
these microorganisms do not contaminate the environment.
To achieve this, good laboratory practices are essential, including personal hygiene and aseptic working techniques which exclude extraneous contamination as far as possible.
Only limited information on the precautions to be taken during microbiological examinations is given in this document, so a thorough knowledge of the microbiological techniques and microorganisms involved is essential. It is important that examinations are conducted safely, correctly and as carefully as possible, including monitoring and recording aspects that can affect results, calculating numbers of microorganisms and assessing the uncertainty of test results.
The most common risks and their control in the microbiological laboratory are given in this document. However, work processes in each laboratory can differ and appropriate risk analysis should be considered to ensure good laboratory practices. Periodic evaluation and control of critical points not only maintains safe and hygienic practices but can also improve reliability of test results.
The purpose of this document is to help to ensure the validity of microbiology examinations in the food chain. In particular, to ensure that general techniques for conducting examinations are the same in all laboratories, to achieve consistent results in different laboratories and to contribute to safety of laboratory personnel by preventing risks of infection.
This document includes the main measures necessary for conducting the wide range of microbiological examinations. Additional information is available from the literature listed in the Bibliography (see References [43] to [47]).
In this document, the following verbal forms are used:
“shall” indicates a requirement;
“should” indicates a recommendation;
“may” indicates a permission;
“can” indicates a possibility or a capability.
In addition, the imperative mood is used to give instructions or where actions are required.
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International StandardISO 7218:2024(en)
Microbiology of the food chain — General requirements and guidance for microbiological examinations

1Scope

This document specifies general requirements and gives guidance on microbiological examinations.
It is applicable to:
the implementation of specific horizontal or vertical International Standards developed by ISO/TC 34/SC 9 or ISO/TC 34/SC 5 for detection or enumeration of microorganisms, named hereafter “specific standards”;
good laboratory practices for microbiology laboratories testing samples from the food chain;
guidance for microbiological laboratories testing samples from the food chain on the technical requirements for conforming to ISO/IEC 17025.
The requirements of this general standard supersede corresponding ones in existing specific standards.
Additional instructions for examinations using the polymerase chain reaction (PCR) are specified in ISO 22174.
This document is applicable to examinations for bacteria, yeasts and moulds and can be used, if supplemented with specific guidance, for parasites and viruses. It does not apply to examinations for toxins or other metabolites (e.g. amines) from microorganisms.
This document is applicable to microbiology of the food chain, from primary production stage to food and animal feed products, including the premises where the food or feed production and handling takes place. It is also applicable to the microbiological examination of water where water is used in food production or is regarded as a food in national legislation.

2Normative references

There are no normative references in this document.

3Terms and definitions

For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
ISO Online browsing platform: available at https://www.iso.org/obp
IEC Electropedia: available at https://www.electropedia.org/
3.1
food chain
sequence of the stages in the production, processing, distribution, storage and handling of a food (3.2) and its ingredients, from primary production to consumption
Note 1 to entry: The food chain includes the environment of primary production, food and feed production, and handling.
Note 2 to entry: The food chain also includes the packaging materials intended to come into contact with food, feed (3.3) or raw materials.
[SOURCE: ISO 22000:2018, 3.20, modified — Notes to entry replaced.]
3.2
food
products intended for human consumption
substance (ingredient), whether processed, semi-processed or raw, which is intended for human consumption, and includes beverages and any substance which has been used in the manufacture, preparation or treatment of “food” but does not include cosmetics or tobacco or substances (ingredients) used only as drugs
[SOURCE: CAC/GL 81-2013, 6, modified — Admitted term added. “(ingredient)” added, “beverages” replaced “drink” and “chewing-gum” deleted in the definition.]
3.3
feed
products for feeding animals
single or multiple product(s), whether processed, semi-processed or raw, which is (are) intended to be fed to animals
[SOURCE: ISO 22000:2018, 3.16, modified — Admitted term added. “food-producing” deleted in the definition. Note 1 to entry replaced.
Note 1 to entry: These products are intended for food-producing animals and non-food producing animals such as pets.
3.4
food or feed production and handling
any operation in the processing (e.g. preparation, cooking, packaging), storage, transport, distribution and service of food (3.2) or feed (3.3)
[SOURCE: ISO/TS 22002-2:2013, 3.9, modified — “or feed production and” added in the term. “processing (e.g. preparation, cooking, packaging)” replaced “preparation, processing, cooking, packaging”, and “or feed” added in the definition.]
3.5
primary production stage
stage of the food chain (3.1) at which the production, rearing or growing of primary products, including harvesting, milking and farmed animal production before slaughter, takes place
Note 1 to entry: It also includes hunting, fishing and the harvesting of wild products.
3.6
horizontal method
method for microbiological examination that is broadly applicable to samples within the food chain (3.1), excluding any documented limitations
3.7
vertical method
sectorial method
method for microbiological examination that is specifically applicable to samples (e.g. from primary production stage (3.5)), a product or a group of products (e.g. milk and milk products, meat and meat products, fish and fishery products, feed (3.3))
3.8
specific standard
standardized reference method for the examination (e.g. detection, enumeration, confirmation or identification) of a specific microorganism or group of microorganisms
Note 1 to entry: A specific standard can describe a horizontal method (3.6) or a vertical method (3.7).
3.9
general standard
supporting document describing general guidance and requirements necessary for application of specific standards (3.8)
3.10
strain
progeny or subculture of a single isolated colony in pure culture that displays the phenotypic characteristics or possesses the molecular attributes/properties as identified with being associated within the classification of the species of that microorganism
3.11
target strain
strain (3.10), defined according to the scope of the method
[SOURCE: ISO 16140-1:2016, 2.74, modified — “method” replaced “reference method that is expected to be detected or enumerated by the alternative method”.]
3.12
target organism
microorganism that is the designated analyte for a microbiological examination
[SOURCE: ISO 22117:2019, 3.1, modified — “microbiological examination” replaced “proficiency testing sample”.]
3.13
laboratory strain
microorganism that is defined to at least the genus and species level, and characterized biochemically, and/or serologically and/or with molecular testing, and preferably originating from the food chain (3.1)
3.14
reference strain
microorganism obtained directly from an official culture collection or reference laboratory and defined to at least the genus and species level, catalogued and described according to its characteristics and preferably originating from food (3.2), food production areas, primary production stages (3.5), animals or water, as applicable
[SOURCE: ISO 22117:2019, 3.4]
3.15
natural background microorganism
microorganism that is naturally present or can be introduced to compete with or mimic the target microorganism
[SOURCE: ISO 22117:2019, 3.2, modified — “natural background microorganism” replaced “background flora” as the term. “included in a proficiency testing sample” deleted in the definition.]
3.16
matrix
all the components of the sample
[SOURCE: ISO 16140-1:2016, 2.38, modified — “(product)” deleted in the term.]
3.17
biological resource centre
BRC
service provider or repository of the living cells, genomes of organisms and information relating to heredity and the functions of biological systems
Note 1 to entry: BRCs contain collections of culturable organisms (e.g. microorganisms), replicable parts of these (e.g. genomes, plasmids, viruses, cDNAs), viable but not yet culturable organisms, cells and tissues, as well as databases containing molecular, physiological and structural information relevant to these collections and related informatics
[SOURCE: OECD, 2007[44]]
3.18
microbial (sub)type
group of closely related microorganisms (within a species) distinguished by their shared specific characteristics as determined by, for example, serological testing (serotype) or molecular testing (genotype)
[SOURCE: ISO 16140-6:2019, 3.5]
3.19
challenge testing
study of the growth or inactivation of microorganism(s) artificially inoculated in food (3.2)
[SOURCE: ISO 20976-1:2019, 3.5]
3.20
accuracy
accuracy of measurement
measurement accuracy
closeness of agreement between a measured quantity value and a true quantity value of a measurand
[SOURCE: ISO/IEC Guide 99:2007, 2.13, modified — “accuracy” replaced “measurement accuracy” as the preferred term. Notes to entry deleted.]
3.21
resolution
smallest change in a quantity being measured that causes a perceptible change in the corresponding indication
[SOURCE: ISO/IEC Guide 99:2007, 4.14, modified — Notes to entry deleted.]
3.22
uncertainty
uncertainty of measurement
measurement uncertainty
non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used
[SOURCE: ISO/IEC Guide 99:2007, 2.26, modified — “uncertainty” replaced “measurement uncertainty” as the preferred term. Notes to entry deleted.]
3.23
calibration
set of operations that establish, under specified conditions, the relationship between values indicated by a measuring instrument or measuring system, or values represented by a material measure, and the corresponding known values of a reference standard
3.24
verification
provision of objective evidence that a given item fulfils specified requirements
[SOURCE: ISO/IEC Guide 99:2007, 2.44, modified — Examples and notes to entry deleted.]
3.25
contamination
undesirable presence of microorganisms in the environment, on surfaces (including human skin) or in (or on) laboratory samples
3.26
cross-contamination
unintentional transfer of microorganisms or their constituents, such as DNA, or metabolites from one area or article to another
Note 1 to entry: This can include, but is not limited to, transfer from:
the laboratory environment to laboratory samples;
laboratory personnel to laboratory samples;
one laboratory sample to other laboratory samples;
one laboratory area to another;
the laboratory area to adjacent production areas.
3.27
process control
internal quality control (IQC) system that is used to confirm acceptable conditions of the entire process have been achieved
Note 1 to entry: This includes the use of a target organism that is tested in accordance with the method from start to finish with each batch of samples, as well as positive, negative and blank samples that are used to confirm the acceptability of media/reagents and consumable supplies, and of the incubation environment (temperature/equipment), and to confirm the competence of personnel.
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