Microbiological Analysis of Food and Water (eBook)

Guidelines for Quality Assurance

N.F. Lightfoot, E.A. Maier (Herausgeber)

eBook Download: PDF

1998 | 1. Auflage
292 Seiten
Elsevier Science (Verlag)
978-0-08-053651-4 (ISBN)

Infos

With the help of leading Quality Assurance (QA) and Quality Control (QC) microbiology specialists in Europe, a complete set of guidelines on how to start and implement a quality system in a microbiological laboratory has been prepared, supported by the European Commission through the Measurement and Testing Programme. The working group included food and water microbiologists from various testing laboratories, universities and industry, as well as statisticians and QA and QC specialists in chemistry.

This book contains the outcome of their work. It has been written with the express objective of using simple but accurate wording so as to be accessible to all microbiology laboratory staff. To facilitate reading, the more specialized items, in particular some statistical treatments, have been added as an annex to the book. All QA and QC tools mentioned within these guidelines have been developed and applied by the authors in their own laboratories. All aspects dealing with reference materials and interlaboratory studies have been taken in a large part from the projects conducted within the BCR and Measurement and Testing Programmes of the European Commission.

With so many different quality control procedures, their introduction in a laboratory would appear to be a formidable task. The authors recognize that each laboratory manager will choose the most appropriate procedures, depending on the type and size of the laboratory in question. Accreditation bodies will not expect the introduction of all measures, only those that are appropriate for a particular laboratory.

Features of this book:

&bull, Gives all quality assurance and control measures to be taken, from sampling to expression of results

&bull, Provides practical aspects of quality control to be applied both for the analyst and top management

&bull, Describes the use of reference materials for statistical control of methods and use of certified reference materials (including statistical tools).

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With the help of leading Quality Assurance (QA) and Quality Control (QC) microbiology specialists in Europe, a complete set of guidelines on how to start and implement a quality system in a microbiological laboratory has been prepared, supported by the European Commission through the Measurement and Testing Programme. The working group included food and water microbiologists from various testing laboratories, universities and industry, as well as statisticians and QA and QC specialists in chemistry.This book contains the outcome of their work. It has been written with the express objective of using simple but accurate wording so as to be accessible to all microbiology laboratory staff. To facilitate reading, the more specialized items, in particular some statistical treatments, have been added as an annex to the book. All QA and QC tools mentioned within these guidelines have been developed and applied by the authors in their own laboratories. All aspects dealing with reference materials and interlaboratory studies have been taken in a large part from the projects conducted within the BCR and Measurement and Testing Programmes of the European Commission.With so many different quality control procedures, their introduction in a laboratory would appear to be a formidable task. The authors recognize that each laboratory manager will choose the most appropriate procedures, depending on the type and size of the laboratory in question. Accreditation bodies will not expect the introduction of all measures, only those that are appropriate for a particular laboratory.Features of this book:* Gives all quality assurance and control measures to be taken, from sampling to expression of results* Provides practical aspects of quality control to be applied both for the analyst and top management* Describes the use of reference materials for statistical control of methods and use of certified reference materials (including statistical tools).

Inhalt

Front Cover 1
Microbiological Analysis of Food and Water: 4
Copyright Page 5
Contents 12
Preface 6
List of contributors 10
Chapter 1. Scope and purpose 20
1.1. Introduction 20
1.2. Implications of incorrect results 20
1.3. Quality assurance 21
1.4. Types of laboratories 23
1.5. Elements of a quality assurance programme 24
1.6. Accreditation 26
1.7. Benefits of a quality assurance programme 26
References 27
Chapter 2. Implementation of quality assurance programmes 28
2.1. Introduction 28
2.2. Personnel (see Chapter 3) 29
2.3. Media (see Chapter 6) 30
2.4. Methods (see Chapter 7) 31
2.5. Equipment (see Chapter 5) 31
2.6. Sample handling (see Chapter 4) 32
2.7. Data handling (see Chapter 9) 32
2.8. Quality control systems (see Chapter 8) 33
2.9. Follow-up 34
References 37
Chapter 3. People, management and organization 38
3.1. Introduction 38
3.2. People 39
3.3. Laboratory accommodation and environment 43
3.4. Safety 46
3.5. Working procedures 48
3.6. Communication and customer relations 48
3.7. Complaints management 49
References 50
Chapter 4. Sampling 52
4.1. Introduction 52
4.2. Distribution of organisms in food and water 54
4.3. Sampling plans 55
4.4. Food 56
4.5. Water 61
4.6. Sample records 66
4.7. Sampler training 66
4.8. Sample transport 66
4.9. Sample reception 67
4.10. Summary 67
References 68
Chapter 5. Equipment 70
5.1. Introduction 70
5.2. Types of sterilization apparatus 72
5.3. Steam sterilization 73
5.4. Media preparator 79
5.5. Pressure cooker 82
5.6. Hot-air sterilizers (dry sterilization) 84
5.7. Filter sterilization 86
5.8. Membrane filtration apparatus 88
5.9. Incubators 90
5.10. Water baths 93
5.11. Microwaves 95
5.12. Thermometers 95
5.13. pH meters 96
5.14. Balances 97
5.15. Deionizing and distillation apparatus 99
5.16. Cold storage 99
5.17. Anaerobic incubation 100
5.18. Colony counters 101
5.19. Microscopes 101
5.20. ELISA plate readers and plate washers 102
5.21. List of equipment and technical specifications 102
Chapter 6. Materials 106
6.1. Introduction 106
6.2. Sample bottles and containers 107
6.3. Laboratory glassware 113
6.4. Pipettes 114
6.5. Petri dishes 115
6.6. Metal utensils 116
6.7. Tubes and closures 116
6.8. Membrane filters 117
6.9. Pads 119
6.10. Deionized/distilled water 120
6.11. Culture media and chemicals 122
References 127
Chapter 7. Quantitative method and procedure assessment 128
7.1. Introduction 128
7.2. Principles of microbiological measurements of water and food 131
7.3. Standardization and validation 137
7.4. Mathematical and technical characteristics of microbiological methods 140
7.5. Selective methods 149
7.6. Comparison and validation of presence/absence tests 153
7.7. Quantitative expression and estimation of uncertainty in microbiological methods 156
7.8. Experimental designs for comparing colony count methods 161
References 165
Chapter 8. Analytical quality control in microbiology 168
8.1. Introduction 168
8.2. First-line checks 170
8.3. Second-line checks 197
8.4. Third-line checks 205
References 206
Chapter 9. Handling and reporting results 210
9.1. Introduction 210
9.2. Samples organized or requested internally 212
9.3. Samples submitted to the laboratory 214
9.4. Examples of request forms and report forms 223
References 223
Chapter 10. Accreditation 240
10.1. Introduction 240
10.2. International aspects of accreditation 240
10.3. The European single market 241
10.4. National accreditation organizations 242
10.5. Accreditation requirements 244
10.6. Achieving accreditation 246
Annex: Statistics for quality assurance in food and water microbiology 248
1. Some basic calculations 249
2. Some basic distributions 254
3. Confidence intervals 262
4. Statistical tests 266
5. Analysis of variance 270
6. References 276
Appendices 278
Appendices A. Example of a membrane filter test, with statistical evaluation 278
Appendices B. Preparation of test sample for first-level quality control of plate and membrane filter counts 280
Subject index 282

Textauszug

Chapter 2

Implementation of quality assurance programmes

2.1 Introduction

The implementation of a quality assurance programme starts with the nomination of a coordinator, who will be in charge of producing the quality assurance manual. The coordinator will lead the implementation programme and, in effect, becomes the quality manager. The relation between coordinator and laboratory management should be clearly defined and responsibilities agreed from the start. The success of the operation will depend to a large extent on the commitment shown by the laboratory management, as the setting up of a good QA programme will take the laboratory staff a significant amount of time.

The first action is to make an inventory of the status quo, i.e. a detailed statement of the existing situation in the laboratory, using the various chapters of this book as a reference.

Secondly, the analytical task of the laboratory (mission statement) should be well defined and agreed with the laboratory management to ensure that the objectives are well understood.

When there is a good understanding of the current practices and objectives, the implementation starts by assuring that all elements of a well-controlled QA programme are put in place and that weak or missing elements are fortified and built into the QA system.

The elements to be covered are given below in a logical order, but the sequence should be adapted to the local situation and another priority order may be established.

A time plan for the different tasks to be performed, with milestones to be met, will help to control the progress of the operation. Depending on the situation found, the implementation may take from a few months to one or two years.

It is recommended that for each task a small team of individuals is chosen and briefed by the coordinator to proceed with that particular task. This prevents the new procedures coming from the top, without the input of the experienced personnel who are responsible for the good execution of the daily operations. The format of all documents to be written should be agreed before the start of the operation.

2.2 Personnel (see Chapter 3)

An up-to-date organization diagram of the department forms the basis for the organization of the QA function. When that is drawn up or updated, a complete set of job descriptions for the individuals in the department should be made so that the responsibilities and authorities for the various tasks of the department can be clarified.

Once the tasks are known, it should be checked whether the skill base of the personnel in the department is sufficient for the jobs to be performed. This will lead to a review of the training needs of the personnel and, as training will take time, it is best to start with a training plan early on.

Once the task of the department has been defined, it may prove necessary to review the laboratory accommodation and facilities, to see whether these match the requirements resulting from this definition.

An important aspect to be checked is the safety requirements for the jobs performed. Testing for pathogens may require specific conditions, to be met as required by national or EU legislation. The appointment of a safety officer with the responsibility to supervise safety aspects of the laboratory is recommended.

2.3 Media (see Chapter 6)

The next step is to bring the quality assurance of the prepared media up to standard.

Media composition should be documented by detailed media recipes. When using dehydrated media or media components of commercial origin, the brands and codes should be detailed in the recipe.

To ensure the quality of dehydrated media and media components, manufacturers will perform their own quality control checks. Results of these quality control checks are summarized in certificates. Laboratories should make sure that batches of dehydrated media or media components are supplied with the relevant analysis certificates, as this is not a routine service. Ordering larger volumes of media of one batch number helps the control of the quality with minimal effort.

The procedure for the preparation of media should be precisely described and the sterilization thereof validated.

Routine checks on the quality of prepared media are sometimes thought to be superfluous as long as the relevant batches of dehydrated media have been checked (in house) before release and the preparation has been under control. The check before release of a batch may be carried out by the ecometric method (Mossel et al., 1980) or by any other reliable quality control procedure (IUMS, 1982). A balance is required between process controls and end product testing.

A routine check on the pH of prepared media after sterilization is essential, but this in itself could be sufficient, assuming that the sterilization process has been under control.

When preparing media, batch numbers of commercial dehydrated media and/or components should be registered, as well as their date of preparation and final pH after sterilization. The sterilization process data should be stored linked with the sterilized batches of prepared media.

Finally, the date of final usage on the relevant batches of prepared media, based on the date of preparation and the shelf life of the relevant media, should be noted.

Shelf life and storage conditions should be part of the media preparation documentation.

2.4 Methods (see Chapter 7)

All methods should be available as written instructions in a uniform format and in the form in which they are used. Where standard methods are followed, reference should be made to these standards. As official standard methods tend to be lengthy, an abbreviated description for use at the bench could be drawn up, this summary giving the key points of the method in the form of a flow sheet supported by a short explanatory text; examples are given in the FAO Manual (Andrews, 1992).

Interpretation and reading of plates may need extra attention. The rules followed by the department should be made explicit and, where confirmation is required, the local practice followed should be specified. Where deviations from official standard methods have become normal practice (as with no routine confirmation of Entero-bacteriaceae from violet red bile glucose agar plates), this should be evident from the documentation.

Minimum performance criteria should be established to allow introduction of new methods in a controlled way.

2.5 Equipment (see Chapter 5)

All procedures should be in place for equipment calibration and use; any checks that have to be done before their use in the laboratory should be specified.

All equipment should be registered; the frequency of maintenance should be indicated here, as well as what this maintenance comprises and who is responsible for carrying it out.

Equipment that has broken down should be labelled as such; its repair should be recorded in the relevant equipment file.

Critical equipment, i.e. equipment that may influence, directly or indirectly, the analysis results when not operating properly, should be calibrated on a regular basis. Examples of critical equipment are balances, pH meters, volume dosing equipment, thermometers, incubators, water baths and refrigerators. The frequency of calibration should be documented as well.

The information relating to calibration, maintenance, etc. of the equipment may be recorded in instrument books for all the types of equipment available.

2.6 Sample handling (see Chapter 4)

Sampling starts with a good sampling instruction; development of a suitable protocol is a key activity. Furthermore, all requirements for sample transport and sample processing should be defined and implemented.

When sampling procedures are recorded, it may prove useful first to audit the actual sampling process to check that no unrealistic assumptions are made.

Where sampling is outside the control of the department, rules should be formulated about the processing of samples with an unknown sample history. It may not always be possible or necessary to reject such samples, but in the laboratory report this should be stated to prevent unjustified conclusions being drawn from the analytical findings.

2.7 Data handling (see Chapter 9)

All procedures for reading, recording and processing of microbiological data should be drawn up. The introduction of one or more uniform data collection sheets, in which the raw data are collected, should get priority. Once such a form is completed and signed by the analyst, the results can be transferred to a computer file or report form and reported to the requesting customer.

Preferably, data should not be communicated as analytical data alone; some interpretation of the findings should be added. The authority to interpret data should be clearly defined and interpretation should be restricted to data for which there is a good understanding of the sampling procedures and the actual product under investigation. Otherwise, the conclusions should be restricted to the sample analysed, without widening these to the material from which the sample was taken.

Before the interpretation of sample data, the results of any QC checks carried out with these samples should be taken into consideration. A system to ensure this should be set up as part of the laboratory organization.

Where statistical checks on the performance of the laboratory are set up, suitable means should be available to perform such tests and to check their actual significance on...

Produkt-Details

• Erscheint lt. Verlag: 22.4.1998
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Gesundheitsfachberufe
• Themenwelt: Studium ► 2. Studienabschnitt (Klinik) ► Pharmakologie / Toxikologie
• Themenwelt: Naturwissenschaften ► Chemie ► Analytische Chemie
• Themenwelt: Naturwissenschaften ► Chemie ► Technische Chemie
• Themenwelt: Technik ► Lebensmitteltechnologie
• Themenwelt: Technik ► Umwelttechnik / Biotechnologie
• ISBN-10: 0-08-053651-4 / 0080536514
• ISBN-13: 978-0-08-053651-4 / 9780080536514