EN ISO 11737-1:2006

Sterilization of medical devices - Microbiological methods - Part 1: Determination of a population of microorganisms on products (ISO 11737-1:2006)

ISO 11737-1:2006 specifies requirements and provides guidance for the enumeration and microbial characterization of the population of viable micro-organisms on or in a medical device, component, raw material or package.

Sterilisation von Medizinprodukten - Mikrobiologische Verfahren - Teil 1: Bestimmung der Population von Mikroorganismen auf Produkten (ISO 11737-1:2006)

Dieser Teil von ISO 11737 legt Anforderungen für die Zählung und mikrobiologische Charakterisierung der Population lebensfähiger Mikroorganismen auf oder in einem Medizinprodukt, Bauteil, Rohstoff oder einer Verpackung fest und liefert dazu eine Anleitung.
ANMERKUNG 1   Art und Umfang der mikrobiologischen Charakterisierung hängen von der vorgesehenen Verwendung der Daten über die Keimbelastung ab.
Dieser Teil von ISO 11737 legt keine Anforderungen für die Zählung oder Identifizierung kontaminierender Viren oder Protozoen fest.
ANMERKUNG 2   Weiterhin beziehen sich die in dieser Norm festgelegten Anforderungen nicht auf Entnahme und Nachweis der Erreger spongiformer Enzephalopathien wie Scrapie, bovine spongiforme Enzephalopathie und Creutzfeldt-Jakob-Krankheit.
Dieser Teil von ISO 11737 legt keine Anforderungen an die mikrobiologische Überwachung der Umgebung fest, in der Medizinprodukte hergestellt werden.

Stérilisation des dispositifs médicaux - Méthodes microbiologiques - Partie 1: Détermination d'une population de micro-organismes sur des produits (ISO 11737-1:2006)

L'ISO 11737-1:2006 spécifie les exigences et fournit les directives pour le dénombrement et la caractérisation microbienne de la population de micro-organismes viables sur ou dans un dispositif médical, un composant, une matière première ou un emballage.

Sterilizacija medicinskih pripomočkov - Mikrobiološke metode - 1. del: Določevanje populacije mikroorganizmov na izdelku (ISO 11737-1:2006)

General Information

• Status: Withdrawn
• Publication Date: 31-Mar-2006
• Withdrawal Date: 13-Apr-2025
• ICS: 07.100.10 - Medical microbiology
• ICS: 11.080.01 - Sterilization and disinfection in general
• Technical Committee: CEN/TC 204 - Sterilization of medical devices
• Drafting Committee: CEN/TC 204 - Sterilization of medical devices
• Current Stage: 9960 - Withdrawal effective - Withdrawal
• Start Date: 31-Jan-2018
• Completion Date: 14-Apr-2025
• Directive: 90/385/EEC - Council Directive 90/385/EEC of 20 June 1990 on the approximation of the laws of the Member States relating to active implantable medical devices
• Directive: 93/42/EEC - Council Directive 93/42/EEC of 14 June 1993 concerning medical devices
• Mandate: M/BC/CEN/89/9 - Joint Standardization request to CEN/CENELEC concerning harmonized standards relating to horizontal aspects in the field of medical devices
• Ref Project: SIST EN ISO 11737-1:2006 - Sterilization of medical devices - Microbiological methods - Part 1: Determination of a population of microorganisms on products (ISO 11737-1:2006)

Relations

• Replaces: EN 1174-1:1996 - Sterilization of medical devices - Estimation of the population of micro-organisms on product - Part 1: Requirements
• Effective Date: 22-Dec-2008
• Replaces: EN 1174-3:1996 - Sterilization of medical devices - Estimation of the population of micro-organisms on product - Part 3: Guide to the methods for validation of microbiological techniques
• Effective Date: 22-Dec-2008
• Replaces: EN 1174-2:1996 - Sterilization of medical devices - Estimation of the population of micro-organisms on product - Part 2: Guidance
• Effective Date: 22-Dec-2008
• Replaced By: EN ISO 11737-1:2018 - Sterilization of health care products - Microbiological methods - Part 1: Determination of a population of microorganisms on products (ISO 11737-1:2018)
• Effective Date: 13-May-2014
• Corrected By: EN ISO 11737-1:2006/AC:2009 - Sterilization of medical devices - Microbiological methods - Part 1: Determination of a population of microorganisms on products (ISO 11737-1:2006/Cor 1:2007)
• Effective Date: 08-Jun-2022

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2006
1DGRPHãþD
SIST EN 1174-1:2000
SIST EN 1174-2:2000
SIST EN 1174-3:2000
6WHULOL]DFLMDPHGLFLQVNLKSULSRPRþNRY0LNURELRORãNHPHWRGHGHO
'RORþHYDQMHSRSXODFLMHPLNURRUJDQL]PRYQDL]GHONX,62
Sterilization of medical devices - Microbiological methods - Part 1: Determination of a
population of microorganisms on products (ISO 11737-1:2006)
Sterilisation von Medizinprodukten - Mikrobiologische Verfahren - Teil 1: Bestimmung der
Population von Mikroorganismen auf Produkten (ISO 11737-1:2006)
Stérilisation des dispositifs médicaux - Méthodes microbiologiques - Partie 1:
Détermination d'une population de micro-organismes sur des produits (ISO 11737-
1:2006)
Ta slovenski standard je istoveten z: EN ISO 11737-1:2006
ICS:
07.100.10 Medicinska mikrobiologija Medical microbiology
11.080.01 Sterilizacija in dezinfekcija na Sterilization and disinfection
splošno in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 11737-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2006
ICS 07.100.10; 11.080.01 Supersedes EN 1174-1:1996, EN 1174-2:1996,
EN 1174-3:1996
English Version
Sterilization of medical devices - Microbiological methods - Part
1: Determination of a population of microorganisms on products
(ISO 11737-1:2006)
Stérilisation des dispositifs médicaux - Méthodes Sterilisation von Medizinprodukten - Mikrobiologische
microbiologiques - Partie 1: Détermination d'une population Verfahren - Teil 1: Bestimmung der Population von
de micro-organismes sur des produits (ISO 11737-1:2006) Mikroorganismen auf Produkten (ISO 11737-1:2006)
This European Standard was approved by CEN on 23 March 2006.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.

This European Standard 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11737-1:2006: E
worldwide for CEN national Members.

Foreword
This document (EN ISO 11737-1:2006) has been prepared by Technical Committee ISO/TC 198
"Sterilization of health care products" in collaboration with Technical Committee CEN/TC 204
"Sterilization of medical devices", the secretariat of which is held by BSI.

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 October 2006, and conflicting national standards
shall be withdrawn at the latest by October 2006.

This document supersedes EN 1174-1:1996, EN 1174-2:1996 and EN 1174-3:1996.

This document has been prepared under a mandate given to CEN by the European Commission
and the European Free Trade Association, and supports essential requirements of EU Directive(s).

For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this
document.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Cyprus,
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

Endorsement notice
The text of ISO 11737-1:2006 has been approved by CEN as EN ISO 11737-1:2006 without any
modifications.
ANNEX ZA
(informative)
Relationship between this European Standard and the Essential
Requirements of EU Directives 90/385/EEC concerning active
implantable medical devices, 93/42/EEC concerning medical devices
and 98/79/EC concerning in vitro diagnostic medical devices

This European Standard has been prepared under a mandate given to CEN by the European

Commission and the European Free Trade Association to provide one means of conforming to
Essential Requirements of the New Approach Directives 90/385/EEC concerning active
implantable medical devices, 93/42/EEC concerning medical devices and 98/79/EC concerning in
vitro diagnostic medical devices.

Once this standard is cited in the Official Journal of the European Communities under thos
Directives and has been implemented as a national standard in at least one Member State,
compliance with the normative clauses of this standard given in Table ZA.1 confers, within the
limits of the scope of this standard, a presumption of conformity with the corresponding Essential
Requirements of those Directives and associated EFTA regulations.

Table ZA.1 — Correspondence between this European Standard and Directives 90/385 EEC
concerning active implantable medical devices, 93/42/EEC concerning medical devices and
98/79/EC concerning in vitro diagnostic medical devices

Clause(s)/Sub- Essential Essential Essential Qualifying
clause(s) of this Requirements Requirements Requirements remarks/Notes
European Standard (ERs) of Directive (ERs) of (ERs) of Directive
90/385/EEC Directive 98/79/EC
93/42/EEC
In part
4, 5, 6, 7, 8, 9, 10, 11, 7 8.3 2.3
In part
4, 5, 6, 7, 8, 9, 10, 11, 8.4 2.4
WARNING: Other requirements and other EU Directives may be applicable to the product(s) falling
within the scope of this standard.

INTERNATIONAL ISO
STANDARD 11737-1
Second edition
2006-04-01
Sterilization of medical devices —
Microbiological methods —
Part 1:
Determination of a population of
microorganisms on products
Stérilisation des dispositifs médicaux — Méthodes microbiologiques —
Partie 1: Détermination d'une population de micro-organismes sur des
produits
Reference number
ISO 11737-1:2006(E)
©
ISO 2006
ISO 11737-1:2006(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2006
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2006 – All rights reserved

ISO 11737-1:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Quality management system elements .4
4.1 Documentation. 4
4.2 Management responsibility . 4
4.3 Product realization. 4
4.4 Measurement, analysis and improvement — Control of nonconforming product . 5
5 Selection of product . 5
5.1 General. 5
5.2 Sample item portion (SIP) . 5
6 Methods of determination and microbial characterization of bioburden . 6
6.1 Determination of bioburden. 6
6.2 Microbial characterization of bioburden . 7
7 Validation of method for determining bioburden . 7
8 Routine determination of bioburden and interpretation of data. 7
9 Maintenance of the method of determination of bioburden. 8
9.1 Changes to the product and/or manufacturing process . 8
9.2 Changes to the method of determination of bioburden . 8
9.3 Revalidation of the method of determination of bioburden . 8
Annex A (informative) Guidance on determination of a population of microorganisms on product. 9
Annex B (informative) Guidance on methods of determination of bioburden. 22
Annex C (informative) Validation of bioburden methods. 31
Bibliography . 34

ISO 11737-1:2006(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11737-1 was prepared by Technical Committee ISO/TC 198, Sterilization of health care products.
This second edition cancels and replaces the first edition (ISO 11737-1:1995) which has been technically
revised and ISO 11737-3:2004 whose contents it now incorporates.
ISO 11737 consists of the following parts, under the general title Sterilization of medical devices —
Microbiological methods:
⎯ Part 1: Determination of a population of microorganisms on products
⎯ Part 2: Tests of sterility performed in the validation of a sterilization process
iv © ISO 2006 – All rights reserved

ISO 11737-1:2006(E)
Introduction
A sterile medical device is one that is free of viable microorganisms. International standards that specify
requirements for validation and routine control of sterilization processes, require, when it is necessary to
supply a sterile medical device, that adventitious microbiological contamination of a medical device prior to
sterilization be minimized. Even so, medical devices produced under standard manufacturing conditions in
accordance with the requirements for quality management systems (see, for example, ISO 13485) may, prior
to sterilization, have microorganisms on them, albeit in low numbers. Such products are non-sterile. The
purpose of sterilization is to inactivate the microbiological contaminants and thereby transform the non-sterile
products into sterile ones.
The kinetics of inactivation of a pure culture of microorganisms by physical and/or chemical agents used to
sterilize medical devices can generally best be described by an exponential relationship between the numbers
of microorganisms surviving and the extent of treatment with the sterilizing agent; inevitably this means that
there is always a finite probability that a microorganism may survive regardless of the extent of treatment
applied. For a given treatment, the probability of survival is determined by the number and resistance of
microorganisms and by the environment in which the organisms exist during treatment. It follows that the
sterility of any one product in a population subjected to sterilization processing cannot be guaranteed and the
sterility of a processed population is defined in terms of the probability of there being a viable microorganism
present on a product item.
Generic requirements of the quality management system for design and development, production, installation
and servicing are given in ISO 9001 and particular requirements for quality management systems for medical
device production are given in ISO 13485. The standards for quality management systems recognize that, for
certain processes used in manufacturing, the effectiveness of the process cannot be fully verified by
subsequent inspection and testing of the product. Sterilization is an example of such a process. For this
reason, sterilization processes are validated for use, the performance of the sterilization process is monitored
routinely and the equipment is maintained.
International Standards specifying procedures for the validation and routine control of the processes used for
the sterilization of medical devices have been prepared (see, for example, ISO 11135, ISO 11137 series and
ISO 17665). However, it is important to be aware that exposure to a properly validated and accurately
controlled sterilization process is not the only factor associated with the provision of assurance that the
product is sterile and, in this respect, suitable for its intended use. Furthermore, for the effective validation and
routine control of a sterilization process, it is important to be aware of the microbiological challenge that is
presented in the process, in terms of number, characteristics and properties of microorganisms.
The term bioburden is used to describe the population of viable microorganisms present on or in product
and/or a sterile barrier system. A knowledge of bioburden can be used in a number of situations as part of:
⎯ validation and revalidation of sterilization processes;
⎯ routine monitoring for control of manufacturing processes;
⎯ monitoring of raw materials, components or packaging;
⎯ assessment of the efficiency of cleaning processes;
⎯ an overall environmental monitoring programme.
Bioburden is the sum of the microbial contributions from a number of sources, including raw materials,
manufacturing of components, assembly processes, manufacturing environment, assembly/manufacturing
aids (e.g., compressed gases, water, lubricants), cleaning processes and packaging of finished product. To
control bioburden, attention must be given to the microbiological status of these sources.
ISO 11737-1:2006(E)
It is not possible to enumerate the bioburden exactly and, in practice, a determination of bioburden is made
using a defined method. Definition of a single method for use in the determination of bioburden in all situations
is not practicable because of the wide variety of designs and materials of construction of medical devices. Nor
is it possible to define a single technique to be used in all situations for the removal of microorganisms in
preparation for enumeration. Furthermore, the selection of conditions for enumeration of microorganisms will
be influenced by the types of microorganism likely to be present on or in medical devices.
This part of ISO 11737 specifies the requirements to be met in the determination of bioburden. The
requirements are the normative parts of this part of ISO 11737 with which compliance is claimed. The
guidance given in the informative annexes is not normative and is not provided as a checklist for auditors. The
guidance provides explanations and methods that are regarded as being a suitable means for complying with
the requirements. Methods other than those given in the guidance may be used, if they are effective in
achieving compliance with the requirements of this part of ISO 11737.

vi © ISO 2006 – All rights reserved

INTERNATIONAL STANDARD ISO 11737-1:2006(E)

Sterilization of medical devices — Microbiological methods —
Part 1:
Determination of a population of microorganisms on products
1 Scope
This part of ISO 11737 specifies requirements and provides guidance for the enumeration and microbial
characterization of the population of viable microorganisms on or in a medical device, component, raw
material or package.
NOTE 1 The nature and extent of microbial characterization is dependent on the intended use of the bioburden data.
This part of ISO 11737 does not specify requirements for the enumeration or identification of viral or protozoan
contaminants.
NOTE 2 Furthermore, the requirements specified in this part of ISO 11737 are not intended to address the removal and
detection of the causative agents of spongiform encephalopathies such as scrapie, bovine spongiform encephalopathy
and Creutzfeldt-Jakob disease.
This part of ISO 11737 does not specify requirements for the microbiological monitoring of the environment in
which medical devices are manufactured.
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.
ISO 10012, Measurement management systems — Requirements for measurement processes and
measuring equipment
ISO 13485:2003, Medical devices — Quality management systems — Requirements for regulatory purposes
ISO/IEC 17025:2005, General requirements for the competence of testing and calibration laboratories
ISO 11737-1:2006(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
bioburden
population of viable microorganisms on or in product and/or sterile barrier system
[ISO/TS 11139:2006, definition 2.2]
3.2
correction
action to eliminate a detected nonconformity
NOTE A correction can be made in conjunction with a corrective action (3.4).
[ISO 9000:2005, definition 3.6.6]
3.3
correction factor
numerical value applied to compensate for incomplete removal from product and/or culture of microorganisms
3.4
corrective action
action to eliminate the cause of a detected nonconformity or other undesirable situation
NOTE 1 There can be more than one cause for a nonconformity.
NOTE 2 Corrective action is taken to prevent recurrence whereas preventive action (3.9) is taken to prevent
occurrence.
NOTE 3 There is a distinction between correction (3.2) and corrective action.
[ISO/TS 11139:2006, definition 2.8]
3.5
culture conditions
combination of growth media and manner of incubation used to promote germination, growth and/or
multiplication of microorganisms
NOTE The manner of incubation may include the temperature, time and any other conditions specified for incubation.
[ISO/TS 11139:2006, definition 2.10]
3.6
establish
determine by theoretical evaluation and confirm by experimentation
[ISO/TS 11139:2006, definition 2.17]
3.7
medical device
instrument, apparatus, implement, machine, appliance, implant, in vitro reagent or calibrator, software,
material or other related article, intended by the manufacturer to be used, alone or in combination, for human
beings for one or more of the specific purpose(s) of:
⎯ diagnosis, prevention, monitoring, treatment or alleviation of disease;
⎯ diagnosis, monitoring, treatment, alleviation of or compensation for an injury;
⎯ investigation, replacement, modification or support of the anatomy or of a physiological process;
2 © ISO 2006 – All rights reserved

ISO 11737-1:2006(E)
⎯ supporting or sustaining life;
⎯ control of conception;
⎯ disinfection of medical devices;
⎯ providing information for medical purposes by means of in vitro examination of specimens derived from
the human body;
and which does not achieve its primary intended action in or on the human body by pharmacological,
immunological or metabolic means, but which may be assisted in its function by such means
NOTE This definition from ISO 13485:2003 has been developed by the Global Harmonization Task Force (GHTF
2002).
[ISO 13485:2003]
3.8
microbial characterization
process by which microorganisms are grouped into categories
NOTE Categories may be broadly based, for example, on the use of selective media, colony or cellular morphology,
staining properties or other characteristics.
[ISO/TS 11139:2006, definition 2.25]
3.9
preventive action
action to eliminate the cause of a potential nonconformity or other undesirable potential situation
NOTE 1 There can be more than one cause for a potential nonconformity.
NOTE 2 Preventive action is taken to prevent occurrence whereas corrective action (3.4) is taken to prevent
recurrence.
[ISO 9000:2005, definition 3.6.4]
3.10
product
result of a process
NOTE For the purposes of sterilization standards, the product is tangible and can be raw material(s), intermediate(s),
sub-assembly(ies) and health care products.
[ISO 9000:2005, definition 3.4.2]
3.11
recognized culture collection
depository authority under the Budapest Treaty on “The International Recognition of the Deposit of
Microorganisms for the Purposes of Patent and Procedure”
[ISO/TS 11139:2006, definition 2.38]
3.12
recovery efficiency
measure of the ability of a specified technique to remove and/or culture microorganisms from product
3.13
sample item portion
SIP
defined part of a medical device that is tested
ISO 11737-1:2006(E)
3.14
specify
stipulate in detail within an approved document
[ISO/TS 11139:2006, definition 2.42]
3.15
validation
documented procedure for obtaining, recording and interpreting the results required to establish that a process
will consistently yield product complying with predetermined specifications
NOTE In the context of determination of bioburden, the “process” is the test methodology and the “product” is the test
result. The validation of a technique for the determination of bioburden consists of a series of investigations to assess the
effectiveness and reproducibility of the test method.
[ISO/TS 11139:2006, definition 2.55]
4 Quality management system elements
4.1 Documentation
4.1.1 Procedures for determination of bioburden shall be specified.
4.1.2 Documents and records required by this part of ISO 11737 shall be reviewed and approved by
designated personnel (see 4.2.1). Documents and records shall be controlled in accordance with ISO 13485
or ISO/IEC 17025.
4.1.3 Records retained shall include all original observations, calculations, derived data and final reports.
The records shall include the identity of all personnel involved in sampling, preparation and testing.
4.1.4 Calculations and data transfers shall be subject to appropriate checks.
4.2 Management responsibility
4.2.1 The responsibility and authority for implementing and performing the procedures described in this part
of ISO 11737 shall be specified. Responsibility shall be assigned to competent personnel in accordance with
ISO 13485 or ISO/IEC 17025.
4.2.2 If the requirements of this part of ISO 11737 are undertaken by organizations with separate quality
management systems, the responsibilities and authority of each party shall be specified.
4.2.3 All items of equipment required for correct performance of the specified tests and measurements shall
be available.
4.3 Product realization
4.3.1 Procedures for purchasing shall be specified. These procedures shall comply with ISO 13485 or
ISO/IEC 17025.
4.3.2 A documented system complying with ISO 13485, ISO/IEC 17025 or ISO 10012 shall be specified for
the calibration of all equipment, including instrumentation for test purposes, used in meeting the requirements
of this part of ISO 11737.
4.3.3 Methods shall be specified for the preparation and sterilization of materials used in the determination
of bioburden, including appropriate quality tests.
4 © ISO 2006 – All rights reserved

ISO 11737-1:2006(E)
4.4 Measurement, analysis and improvement — Control of nonconforming product
Procedures for investigation of out-of-specification results and for correction, corrective action and preventive
action shall be specified. These procedures shall comply with ISO 13485 or ISO/IEC 17025.
5 Selection of product
5.1 General
5.1.1 The procedures for selection and handling of product for determination of bioburden shall ensure that
selected product is representative of routine production including packaging materials and processes.
5.1.2 If product(s) are grouped for the purpose of determination of bioburden, the rationale for inclusion of a
product within a group shall be recorded (see 4.1.2). The rationale shall include criteria to ensure that
bioburden determined for a product selected from the group is representative of the whole group.
5.1.3 Consideration shall be given to the timing of the performance of determination of the bioburden
relative to taking samples, because bioburden determination can be subject to change with the passage of
time.
5.2 Sample item portion (SIP)
If the bioburden is demonstrated as being evenly distributed on and/or in the product item, the SIP may be
selected from any portion of the item. Otherwise, the SIP shall consist of portion(s) of product, selected at
random, which proportionally represent each of the materials from which product is made. If the bioburden
distribution is known, the SIP may be selected from the portion of the product that is considered to be the most
severe challenge to the sterilization process. The SIP can be calculated on the basis of length, mass, volume
or surface area (see Table 1 for examples).
Table 1 — Examples of SIP calculation
Basis for SIP Product
Surface area Implants (non-absorbable)
Powders
Mass Gowns
Implants (absorbable)
Length Tubing (consistent diameter)
Volume Fluid in water cup
NOTE If appropriate, the standard specifying requirements for validation and routine control of the sterilization
process stipulates criteria for the adequacy of SIP.
ISO 11737-1:2006(E)
6 Methods of determination and microbial characterization of bioburden
6.1 Determination of bioburden
6.1.1 Selection of an appropriate method
An appropriate method shall be selected for determination of bioburden. The method shall comprise
techniques for:
a) removal of microorganisms, if appropriate;
b) culturing of microorganisms;
c) enumeration of microorganisms.
The precision shall be determined and shall be appropriate to the purpose for which the data are to be used.
6.1.2 Removal of microorganisms
6.1.2.1 For an identified product where removal of viable microorganisms is part of the method, the
efficiency of removal shall be considered and the outcomes of this consideration recorded (see 4.1.3).
Consideration shall, at least, be given to:
a) ability of the technique to remove microorganisms;
b) possible type(s) of microorganism and their location(s) on product;
c) effect(s) of the removal technique on the viability of microorganisms;
d) the physical or chemical nature of product under test.
6.1.2.2 For an identified product for which removal of viable microorganisms is not part of the method, the
efficiency of enumeration of microorganisms shall be considered and the outcomes of this consideration
recorded (see 4.1.3). Consideration shall, at least, be given to:
a) possible type(s) of microorganism and their location(s) on product;
b) the physical or chemical nature of the product to be tested;
c) aggregates of cells forming single colonies due to in-situ culturing.
6.1.2.3 If the physical or chemical nature of product is such that substances can be released that
adversely affect either the number or the types of microorganism found, then a system shall be used to
neutralize, remove or, if this is not possible, minimize the effect of any such released substance. The
effectiveness of such a system shall be demonstrated.
NOTE Annex B describes techniques that may be used to assess the release of microbicidal or microbiostatic
substances.
6.1.3 Culturing of microorganisms
Culture conditions shall be selected after consideration of the types of microorganism likely to be present. The
results of this consideration and the rationale for the decisions reached shall be recorded (see 4.1.2).
6 © ISO 2006 – All rights reserved

ISO 11737-1:2006(E)
6.1.4 Enumeration of microorganisms
The technique for enumeration shall be selected after consideration of the types of microorganism likely to be
present. The results of this consideration and the rationale for the decisions reached shall be recorded
(see 4.1.2).
6.2 Microbial characterization of bioburden
6.2.1 Appropriate techniques for microbial characterization of bioburden shall be selected.
NOTE Microbial characterization is necessary to detect a change to product microflora that might affect some aspect
of the use of the bioburden data (e.g. establishing a sterilization process).
6.2.2 Microbial characterization shall be accomplished using one or more of the following:
a) staining properties;
b) cell morphology;
c) colony morphology;
d) use of selective culturing;
e) biochemical properties;
f) genetic sequence data for which there is an adequate data base.
7 Validation of method for determining bioburden
7.1 The method for determining of bioburden shall be validated and documented.
7.2 Validation shall consist of the following:
a) assessment of the adequacy of the technique for removal of microorganisms from product, if removal is
part of the method;
b) determination of the recovery efficiency in order that a correction factor be derived;
c) assessment of the adequacy of the enumeration of microorganisms, including culture conditions and
microbiological counting techniques;
d) assessment of the suitability of the technique(s) of microbial characterization.
8 Routine determination of bioburden and interpretation of data
8.1 Routine determination of bioburden shall be performed employing documented sampling plan(s)
defining sample size and sampling frequency.
8.2 Determination of bioburden shall be performed using a method specified for a product or group of
products (see 5.1.2).
8.3 Microbial characterization of bioburden shall be performed to a degree dependent on the purpose for
which the data derived from the determination of bioburden are to be used (see 6.2).
If, on microbial characterization, isolates are recovered that are not part of the normal microflora,
consideration should be given to assessing the properties of these isolates.
ISO 11737-1:2006(E)
8.4 If bioburden data are to be used to establish the extent of treatment of a sterilization process, any
requirements applicable to the use of bioburden data, specified in the appropriate standard for the
development, validation and routine control of the sterilization process, shall be met.
8.5 Acceptable limits for bioburden on or in a medical device shall be specified. This specification shall be
based on previously generated data. If these limits are exceeded, action shall be taken (see 4.4).
8.6 Data derived from determination of bioburden obtained over a period of time shall be used to identify
trends. Acceptable limits shall be reviewed and revised as necessary.
8.7 The application of statistical methods to define sample size, sampling frequency and/or acceptable
limits shall conform to ISO 13485.
9 Maintenance of the method of determination of bioburden
9.1 Changes to the product and/or manufacturing process
Changes to product and/or manufacturing processes shall be reviewed to determine whether they are likely to
alter bioburden. The results of the review shall be recorded (see 4.1.2). If there is potential for alteration of
bioburden, specific determinations of bioburden shall be performed to evaluate the extent and nature of any
change.
9.2 Changes to the method of determination of bioburden
Any change to a routine method of bioburden determination shall be assessed. This assessment shall include:
a) evaluation of the effect of the change on the outcome of determination;
b) establishment of the recovery efficiency of the method following the change.
NOTE The assessment of the change could indicate that the previous validation and recovery efficiency are still
applicable.
9.3 Revalidation of the method of determination of bioburden
The original validation data (see 7.2) and any subsequent revalidation data shall be reviewed at specified
intervals in accordance with a documented procedure. The extent to which revalidation is to be undertaken
shall be determined. The outcome of the review and any revalidation undertaken shall be recorded (see 4.1.3).
8 © ISO 2006 – All rights reserved

ISO 11737-1:2006(E)
Annex A
(informative)
Guidance on determination of a population of microorganisms
on product
NOTE For ease of reference, the numbering in this annex corresponds to that used in the normative part of this part
of ISO 11737.
A.1 Scope
This annex contains guidance on the implementation of the requirements specified in this part of ISO 11737.
The guidance given is not intended to be exhaustive, but to highlight important aspects to which attention
should be given.
Methods other than those given in this annex may be used, but these alternative methods should be
demonstrated as being effective in achieving compliance with the requirements of this part of ISO 11737.
This annex is not intended as a checklist for assessing compliance with the requirements of this part of
ISO 11737.
A.2 Normative references
The requirements of documents included as normative references are requirements of this part of ISO 11737
only to the extent that they are cited in a normative part of this part of ISO 11737; the citation may be to an
entire standard or limited to specific clauses.
A.3 Definitions
No guidance offered.
A.4 Quality management system elements
NOTE It is not a requirement of this part of ISO 11737 to have a full quality management system, but the elements of
a quality management system that are the minimum necessary to control the determination of bioburden as used in the
validation and monitoring of medical devices to be sterilized are normatively referenced at appropriate places in the text
(see, in particular, Clause 4). Attention is drawn to the standards for quality management systems (see ISO 13485) that
control all stages of production or reprocessing of medical devices. National and/or regional regulations for the provision of
medical devices might require a complete implementation of a full quality management system and the assessment of that
system by a third party.
A.4.1 Documentation
In ISO 13485, the requirements in the documentation section relate to the generation and control of
documentation (including specifications and procedures) and records.
Computers may be used in laboratories for direct and indirect collection, processing and/or storage of data.
Both the hardware and software used for such applications should be controlled.
ISO 11737-1:2006(E)
The computer system in use should be identified, both in terms of hardware and software, and any changes in
either of these aspects should be documented and subject to appropriate approval.
If calculations are performed by electronic data processing techniques, the software (e.g., spreadsheet
calculations) should be validated prior to use and records of this validation should be retained.
For software, there should be documentation describing:
⎯ applications software run on the computer system;
⎯ operations software;
⎯ data packages in use.
All software should be acceptance tested before being put into service.
If computer software is developed in-house, suitable procedures should be developed to ensure that:
⎯ documentation on development, including the source code, is retained;
⎯ records of acceptance testing are retained;
⎯ modifications to programs are documented;
⎯ changes in equipment are documented and formally tested before being put into use.
These controls should also be applied to any modification or customizing of commercial software packages.
There should be procedures to detect or prevent unauthorized changes to software programs.
Software programs that organize, tabulate and/or subject data to statistical or other mathematical procedures,
or which otherwise manipulate or analyse the electronically stored data, should permit retrieval of original data
entries. Special procedures for archiving computer data are likely to be required and these procedures should
be documented.
Requirements for control of documents and records are specified in 4.2.3 and 4.2.4 of ISO 13485:2003, or 4.3
and 4.13 of ISO/IEC 17025:2005.
Requirements for technical records are specified in 4.13.2 and 5.4 of ISO/IEC 17025:2005.
See also ISO 90003 for guidance of the application of quality management systems to computer software.
A.4.2 Management responsibility
In ISO 13485, the requirements in the management responsibility section relate to management commitment,
customer focus, quality policy, planning, responsibility, authority and communication, and management review.
In order that the data obtained from performing bioburden determinations are reliable and reproducible, it is
important that the determinations be performed under controlled conditions. Therefore, the laboratory facilities
used for the determinations, whether on the site of the manufacturer of the medical device or located at a
remote location should be managed and operated in accordance with a documented quality system.
The determination of bioburden can involve separate parties, each of whom is responsible for certain
elements of the method or procedure. This part of ISO 11737 requires that the party accepting particular
responsibilities be defined and that this definition of responsibilities be documented. This definition of authority
and responsibility is documented within the quality management system(s) of the identified parties. The party
accepting responsibilities for defined elements is required to assign these elements to competent personnel,
with competence demonstrated through appropriate training and qualification.
10 © ISO 2006 – All rights reserved

ISO 11737-1:2006(E)
If bioburden determinations are performed in a laboratory under the direct management of the manufacturer of
the medical device, the operation of the laboratory resides within the manufacturer's quality management
system. If an external laboratory is used, the laboratory should be formally certified against an appropriate
International Standard (e.g. ISO/IEC 17025).
Any laboratory should be committed to providing a quality service and this commitment should be documented
as a quality policy. The lines of authority and responsibility within the laboratory organization should be
formally established and documented. An individual should be nominated to be responsible for the
establishment of the laboratory quality system and should have the authority to ensure that the system is
implemented.
The operation of the laboratory should be subject to regular internal audits. The results of the audit should be
documented and reviewed by the laboratory management. See 4.14 of ISO/IEC 17025:2005.
Requirements for responsibility and authority are specified in 5.5 of ISO 13485:2003 and requirements for
human resources are specified in 6.2 of ISO 13485:2003.
Requirements for provision of resources are specified in ISO 13485 and requirements for equipment are
specified in 5.5 of ISO/IEC 17025:2005.
A.4.3 Product realization
In ISO 13485, the requirements in the product realization section relate to the product lifecycle from the
determination of customer requirements, design and development, purchasing, control of production, and
calibration of monitoring and measuring devices.
There should be a system for identifying the maintenance requirements for each piece of l
...