Compendium of Methods for the Microbiological Examination of Foods,

| Table of Contents

| i

C O M P E N D I U M O F M E T H O D S F O R T H E

MICROBIOLOGICALEXAMINATION

OF FOODSF O U R T H E D I T I O N

E D I T E D B YFR A N C E S PO U C H DO W N E S

KE I T H IT O

AM E R I C A N PU B L I C HE A LT H AS S O C I AT I O N

Compendium of Methods for the Microbiological Examination of Foods |

ii |

The American Public Health Association is an Association of individuals and organizations working to improve the publics health.It promotes the scientific and professional foundation of public health practice and policy, advocates the conditions for a healthyglobal society, emphasizes prevention, and enhances the ability of members to promote and protect environmental and communityhealth.

American Public Health Association800 I St., NWWashington, DC 20001-3710

Mohammad N. Akhter, MD, MPHExecutive Vice President

2001 by the American Public Health Association

All rights reserved. This book is protected by copyright. No part of this publication may be reproduced, stored in a retrieval system, ortransmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permittedunder Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher or au-thorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA01923, (978) 750-8400, fax (978) 750-4744. Requests to the Publisher for permission should be addressed to the Permissions Department,American Public Health Association, 800 I Street, NW, Washington, DC 20001-3710, fax (202) 777-2531, e-mail: .

10 M 1/01Library of Congress Catalog Card Number: 99-073697

ISBN: 0-87553-175-x

Printed and bound in the United States of America.Cover Design: Sam Dixon DesignTypesetting: Susan Westrate, Joseph R. LoehleSet in: Palatino and UniversePrinting and Binding: Sheridan Books, Inc.

NOTE: Any discussion of medical or legal issues in this publication is being provided for informational purposes only. Nothing inthis publication is intended to constitute medical or legal advice, and it should not be construed as such. This book is not intended to beand should not be used as a substitute for specific medical or legal advice, since medical and legal opinions may only be given in re-sponse to inquiries regarding specific factual situations. If medical or legal advice is desired by the reader of this book, a medical doctoror attorney should be consulted.

The use of trade names and commercial sources by authors in certain chapters of this compendium does not imply endorsement byeither the APHA or the editorial board of this volume.

| Table of Contents

| iii

Contents

About the Editors .............................................................................................................................. xivEditorial Committee.......................................................................................................................... xivAuthors ............................................................................................................................................... xvReviewers .......................................................................................................................................... xixPreface................................................................................................................................................ xxiChapter 1 Laboratory Quality Assurance .................................................................................. 1

1.1 Introduction.................................................................................................................. 11.2 Managements Role In Laboratory Quality Assurance ................................................. 11.3 General Laboratory Operations .................................................................................... 21.4 Personnel ..................................................................................................................... 31.5 Facilities ....................................................................................................................... 41.6 Equipment and Instrumentation .................................................................................. 51.7 Laboratory Glassware and Plasticware ........................................................................ 61.8 Media and Reagents .................................................................................................... 71.9 Record Keeping ........................................................................................................... 91.10 Accreditation of Testing Laboratories ........................................................................ 101.11 References ................................................................................................................ 10

Chapter 2 Sampling Plans, Sample Collection, Shipment, and Preparationfor Analysis ............................................................................................................... 13

2.1 Introduction................................................................................................................ 132.2 General Considerations .............................................................................................. 132.3 Equipment, Materials, and Reagents ......................................................................... 132.4 Precautions ................................................................................................................ 142.5 Procedures................................................................................................................. 142.6 References ................................................................................................................ 23

Chapter 3 Microbiological Monitoring of the Food Processing Environment ..................... 253.1 Introduction................................................................................................................ 253.2 Environmental Sampling Strategies ........................................................................... 253.3 Sampling of SurfacesEquipment and Physical Plant .............................................. 263.4 Rinse Solution Method for Sampling Containers and Processing

Equipment Systems .................................................................................................. 273.5 Surface Contact Methods .......................................................................................... 273.6 Microbiological Air-Sampling Strategies .................................................................... 303.7 Air-Sampling Methods ............................................................................................... 303.8 Aerosol Sampling and Measurement Guidelines....................................................... 343.9 References ................................................................................................................ 34

Chapter 4 Microscopic Methods .............................................................................................. 374.1 Introduction................................................................................................................ 374.2 General Procedures ................................................................................................... 374.3 Fluorescence Microscopy .......................................................................................... 374.4 Stains, Probes, and Indicators ................................................................................... 384.5 Quantitation ............................................................................................................... 404.6 References ................................................................................................................ 42

Chapter 5 Cultural Methods for the Enrichment and Isolation of Microorganisms ........... 455.1 Introduction................................................................................................................ 455.2 Enrichment Methods ................................................................................................. 455.3 Preenrichment ........................................................................................................... 455.4 Selective Enrichment ................................................................................................. 465.5 Quality Assurance of Enrichment and Isolation Method ........................................... 49


iv |

5.6 References ................................................................................................................ 50Chapter 6 Culture Methods for Enumeration of Microorganisms ........................................ 53

6.1 Introduction................................................................................................................ 536.2 Dilutions ..................................................................................................................... 536.3 Plating Techniques ..................................................................................................... 546.4 Most Probable Number Techniques .......................................................................... 586.5 Membrane Filtration .................................................................................................. 616.6 Other Methods .......................................................................................................... 616.7 Anaerobic or Other Atmospheres .............................................................................. 616.8 References ................................................................................................................ 62

Chapter 7 Aerobic Plate Count................................................................................................. 637.1 Introduction................................................................................................................ 637.2 Microbiological Specifications.................................................................................... 637.3 General Considerations.............................................................................................. 637.4 Equipment, Materials and Reagents.......................................................................... 647.5 Precautions and Limitations....................................................................................... 647.6 Standard Procedures ................................................................................................. 647.7 Alternative Methods .................................................................................................. 657.8 References ................................................................................................................ 67

Chapter 8 Enterobacteriaceae , Coliforms, and Escherichia coli as Quality and SafetyIndicators .................................................................................................................. 69

8.1 Introduction................................................................................................................ 698.2 Definitions.................................................................................................................. 708.3 Precautions ................................................................................................................ 718.4 Equipment, Materials and Reagents.......................................................................... 738.5 Sample Preparation.................................................................................................... 738.6 The Enterobacteriaceae ............................................................................................. 748.7 Coliforms ................................................................................................................... 748.8 Fecal Coliform Group ................................................................................................. 768.9 Escherichia coli .......................................................................................................... 768.10 Interpretation of Data: The Value of Enterobacteriaceae, Coliforms,

and E. coli as Indicators of Quality and Indexes of Pathogens .................................. 798.11 Acknowledgments ..................................................................................................... 808.12 References ................................................................................................................ 80

Chapter 9 Enterococci ............................................................................................................... 839.1 Introduction................................................................................................................ 839.2 General Considerations.............................................................................................. 839.3 Equipment, Materials, and Reagents ......................................................................... 849.4 Precautions ................................................................................................................ 849.5 Enumeration of Enterococci ...................................................................................... 859.6 Confirmation of Enterococci ...................................................................................... 859.7 References ................................................................................................................ 86

Chapter 10 Rapid Methods for Detection, Identification, and Enumeration ......................... 8910.1 Introduction................................................................................................................ 8910.2 Antibody-Based Methods .......................................................................................... 89

10.21 Introduction .................................................................................................... 8910.22 Immunofluorescence...................................................................................... 8910.23 Latex Agglutination ......................................................................................... 9010.24 Immunoimmobilization ................................................................................... 9010.25 Enzyme immunoassay.................................................................................... 9010.26 Immunoprecipitate Detection ......................................................................... 9010.27 Immunoaffinity Chromatography and Immunomagnetic Separation .............. 9110.28 References ..................................................................................................... 91

10.3 Nucleic Acid-Based Methods..................................................................................... 9310.31 Introduction .................................................................................................... 9310.32 Hybridization ................................................................................................... 9310.33 PCR................................................................................................................. 9410.34 References ..................................................................................................... 95

10.4 Biochemical and Enzymatic Methods ........................................................................ 9610.41 Introduction .................................................................................................... 9610.42 Miniaturized Microbiological Methods............................................................ 9610.43 Commercial Miniaturized Diagnostic Kits (Minikits) ................................... 96

| Table of Contents

| v

10.44 Chromogenic Media ....................................................................................... 9910.45 Quantitative Enzymatic Methods ................................................................... 9910.46 References ................................................................................................... 100

10.5 Membrane Filtration ................................................................................................ 10010.51 Hydrophobic Grid Membrane Filter .............................................................. 10010.52 References ................................................................................................... 10310.53 Commercial References ............................................................................... 105

10.6 Impedance, Conductance, and Capacitance ............................................................ 10510.61 Theory........................................................................................................... 10510.62 Commercial Systems ................................................................................... 10510.63 General Considerations and Precautions ...................................................... 10610.64 Typical Applications ...................................................................................... 10710.65 Interpretation of Results ............................................................................... 10910.66 References ................................................................................................... 10910.67 Commercial References ............................................................................... 111

10.7 Phage Probes........................................................................................................... 11110.71 Introduction to Bacterial Viruses ................................................................... 11110.72 Bacteriophage-Based Detection Methods.................................................... 11310.73 Conclusions .................................................................................................. 12210.74 References ................................................................................................... 122

Chapter 11 Molecular Typing and Differentiation .................................................................. 12711.1 Introduction.............................................................................................................. 12711.2 Cellular Fatty Acid Analysis ...................................................................................... 127

11.21 Introduction .................................................................................................. 12711.22 Principle ........................................................................................................ 13011.23 Apparatus ..................................................................................................... 13011.24 Reagents ...................................................................................................... 13011.25 General Instructions ..................................................................................... 13011.26 Limitations .................................................................................................... 13111.27 Library ........................................................................................................... 13111.28 Similarity Index ............................................................................................. 13211.29 References ................................................................................................... 132

11.3 Multilocus Enzyme Electrophoresis ......................................................................... 13211.31 Introduction .................................................................................................. 13211.32 General Description of the Method .............................................................. 13311.33 Interpretation of the Gels ............................................................................. 13511.34 References ................................................................................................... 135

11.4 Ribotyping ................................................................................................................ 13611.41 Introduction .................................................................................................. 13611.42 Reagent Preparation ..................................................................................... 13611.43 Lysis of Bacteria and DNA Extraction ........................................................... 13711.44 DNA Digestion and Electrophoresis ............................................................. 13711.45 Electrophoretic Transfer, Denaturation, and UV Cross-Linking ..................... 13711.46 Hybridization and Detection.......................................................................... 13711.47 Patterns: Data Processing ............................................................................ 13711.48 Automated Ribotyping .................................................................................. 13711.49 References ................................................................................................... 138

11.5 Restriction Fragment Length Polymorphism Fingerprinting .................................... 13811.51 Introduction .................................................................................................. 13811.52 Genomic Target ............................................................................................ 13811.53 Restriction Enzyme....................................................................................... 13911.54 Combining Assays ........................................................................................ 13911.55 Other Considerations.................................................................................... 13911.56 References ................................................................................................... 140

11.6 Rapid PCR-Based Methods ..................................................................................... 14011.61 Introduction .................................................................................................. 14011.62 Preparation of Genomic DNA from Bacteria for Use with Rapid Methods .. 14511.63 Notes ............................................................................................................ 14711.64 Preparation, Amplification, Detection and Analysis of PCR for Rapid

Methods ....................................................................................................... 14711.65 Notes ............................................................................................................ 14911.66 References ................................................................................................... 151


vi |

11.7 Pulsed Field Gel Electrophoresis ............................................................................. 15411.71 Introduction .................................................................................................. 15411.72 Utility of PFGE in Foodborne Outbreak Investigations ................................. 15411.73 Interpretation of PFGE Results ..................................................................... 15411.74 Choosing a PFGE Protocol ............................................................................ 15411.75 Standard PFGE Protocol for Subtyping E. coli O157:H7 ............................... 15411.76 References ................................................................................................... 156

Chapter 12 Labor Savings and Automation ........................................................................... 15712.1 Introduction.............................................................................................................. 15712.2 Solid Samples .......................................................................................................... 15712.4 Liquid Samples ........................................................................................................ 15812.5 References .............................................................................................................. 158

Chapter 13 Psychrotrophic Microorganisms .......................................................................... 15913.1 Introduction.............................................................................................................. 15913.2 Review of Methods Used to Enumerate Psychrotrophs in Foods .......................... 16013.3 General Recommendations ..................................................................................... 16113.4 Sample Preparation.................................................................................................. 16213.5 Equipment, Media, Materials, and Reagents........................................................... 16213.6 Procedures for Enumeration of Psychrotrophs........................................................ 16213.7 Precautions .............................................................................................................. 16213.8 Rapid Detection ....................................................................................................... 16213.9 Interpretation ........................................................................................................... 16313.10 References .............................................................................................................. 164

Chapter 14 Thermoduric Microorganisms and Heat Resistance Measurements................ 16714.1 Introduction.............................................................................................................. 16714.2 Heat Resistance Measurements ............................................................................. 16814.3 Methods for the Determination of Heat Resistance................................................ 16914.4 Equipment, Materials, and Procedures.................................................................... 16914.5 Interpretation ........................................................................................................... 17214.6 References .............................................................................................................. 172

Chapter 15 Lipolytic Microorganisms ..................................................................................... 17515.1 Introduction.............................................................................................................. 17515.2 General Considerations............................................................................................ 17715.3 Equipment, Materials, and Reagents ....................................................................... 17715.4 Procedures............................................................................................................... 17815.5 Precautions .............................................................................................................. 17915.6 References .............................................................................................................. 180

Chapter 16 Proteolytic Microorganisms ................................................................................. 18316.1 Introduction.............................................................................................................. 18316.2 General Considerations............................................................................................ 18416.3 Equipment, Materials, and Reagents ....................................................................... 18416.4 Procedures............................................................................................................... 18416.5 Precautions .............................................................................................................. 18516.6 Interpretation ........................................................................................................... 18516.7 References .............................................................................................................. 185

Chapter 17 Halophilic and Osmophilic Microorganisms ....................................................... 18717.1 Introduction.............................................................................................................. 18717.2 Halophilic Microorganisms....................................................................................... 18717.3 Osmophilic Microorganisms .................................................................................... 19017.4 References .............................................................................................................. 192

Chapter 18 Pectinolytic and Pectolytic Microorganisms ....................................................... 19518.1 Introduction.............................................................................................................. 19518.2 Detecting Pectinolytic and Pectolytic Organisms .................................................... 19518.3 Visualization and Assay of Pectic Enzymes ............................................................. 19718.4 Sources of Pectic Enzymes ..................................................................................... 19718.5 Equipment, Materials, and Reagents ....................................................................... 19718.6 Procedures............................................................................................................... 19818.7 Interpretation ........................................................................................................... 19818.8 References .............................................................................................................. 198

Chapter 19 Acid-Producing Microorganisms .......................................................................... 20119.1 Introduction.............................................................................................................. 20119.2 General Considerations............................................................................................ 201

| Table of Contents

| vii

19.3 Limitations ............................................................................................................... 20219.4 Equipment, Materials, and Reagents ....................................................................... 20219.5 Procedures............................................................................................................... 20319.6 References .............................................................................................................. 206

Chapter 20 Yeasts and Molds ................................................................................................... 20920.1 Introduction.............................................................................................................. 20920.2 General Considerations ............................................................................................ 20920.3 Precautions .............................................................................................................. 21020.4 Equipment, Materials, and Reagents ....................................................................... 21020.5 Procedures............................................................................................................... 21020.6 Interpretation ........................................................................................................... 21120.7 New Methods under Development ......................................................................... 21120.8 References .............................................................................................................. 213

Chapter 21 Detection and Enumeration of Heat-Resistant Molds ....................................... 21721.1 Introduction.............................................................................................................. 21721.2 General Considerations ............................................................................................ 21721.3 Equipment, Materials, and Reagents ....................................................................... 21721.4 Procedures............................................................................................................... 21821.5 Precautions .............................................................................................................. 21921.6 Interpretation ........................................................................................................... 21921.7 Taxonomy of Important Heat-Resistant Molds ........................................................ 21921.8 References .............................................................................................................. 221

Chapter 22 Mesophilic Aerobic Sporeformers ....................................................................... 22322.1 Introduction.............................................................................................................. 22322.2 Special Considerations............................................................................................. 22422.3 Sources of Error ....................................................................................................... 22422.4 Equipment, Materials, and Media ............................................................................ 22522.5 Procedures............................................................................................................... 22522.6 Modifications ........................................................................................................... 22622.7 Interpretation ........................................................................................................... 22622.8 References .............................................................................................................. 226

Chapter 23 Mesophilic Anaerobic Sporeformers ................................................................... 22923.1 Introduction.............................................................................................................. 22923.2 General Considerations ............................................................................................ 23123.3 Equipment, Materials, and Media ............................................................................ 23223.4 Precautions .............................................................................................................. 23223.5 Procedures............................................................................................................... 23223.6 Interpretation of Results .......................................................................................... 23523.7 References .............................................................................................................. 235

Chapter 24 Aciduric Flat Sour Sporeformers.......................................................................... 23924.1 Introduction.............................................................................................................. 23924.2 General Considerations ............................................................................................ 24024.3 Equipment, Materials, and Reagents ....................................................................... 24124.4 Procedures............................................................................................................... 24124.5 Maintenance of Cultures ......................................................................................... 24324.6 Precautions and Limitations of the Procedures ....................................................... 24324.7 Interpretation ........................................................................................................... 24324.8 References .............................................................................................................. 243

Chapter 25 Thermophilic Flat Sour Sporeformers ................................................................. 24525.1 Introduction.............................................................................................................. 24525.2 General Considerations ............................................................................................ 24525.3 Equipment, Materials, and Reagents ....................................................................... 24625.4 Precautions .............................................................................................................. 24625.5 Procedure ................................................................................................................ 24625.6 Interpretation of Results .......................................................................................... 24725.7 References .............................................................................................................. 248

Chapter 26 Thermophilic Anaerobic Sporeformers ............................................................... 24926.1 Introduction.............................................................................................................. 24926.2 General Considerations ............................................................................................ 24926.3 Equipment, Materials, and Solutions ....................................................................... 24926.4 Precautions .............................................................................................................. 25026.5 Procedure ................................................................................................................ 250


viii |

26.6 Interpretation ........................................................................................................... 25126.7 References .............................................................................................................. 251

Chapter 27 Sulfide Spoilage Sporeformers ............................................................................ 25327.1 Introduction.............................................................................................................. 25327.2 General Considerations............................................................................................ 25327.3 Equipment, Materials, and Reagents ....................................................................... 25427.4 Precautions and Limitations of Procedure ............................................................... 25427.5 Procedure ................................................................................................................ 25427.6 Interpretation ........................................................................................................... 25527.7 References .............................................................................................................. 255

Chapter 28 Investigation of Foodborne Illness Outbreaks .................................................... 25728.1 Introduction.............................................................................................................. 25728.2 Purpose of Investigation .......................................................................................... 25728.3 Theory of Investigation ............................................................................................ 25828.4 Consideration of Samples ........................................................................................ 25828.5 Equipment, Materials, and Solutions ....................................................................... 25828.6 Investigative Procedures ......................................................................................... 26228.7 Analysis and Conclusion .......................................................................................... 26328.8 Molecular Subtyping TechniquesBacteria ............................................................ 26428.9 Molecular Subtyping TechniquesViruses ............................................................. 26528.10 Conclusion ............................................................................................................... 26528.11 References .............................................................................................................. 265

Chapter 29 Microbial Food Safety Risk Assessment ............................................................. 26729.1 Introduction.............................................................................................................. 26729.2 Risk Assessment: A Tool for Decision-Making ........................................................ 26729.3 Approaches to Microbial Food Safety Risk Assessment ......................................... 26829.4 Steps of Risk Assessment ....................................................................................... 27029.5 Mathematical Approaches to Risk Assessment ...................................................... 27229.6 Monte Carlo Analysis ............................................................................................... 27429.7 Uncertainty & Variability ........................................................................................... 27529.8 Applications of Risk Assessment ............................................................................ 27629.9 Summary ................................................................................................................. 27629.10 References .............................................................................................................. 277Appendix 1: Common Distributions .................................................................................... 280

Chapter 30 Aeromonas, Arcobacter , and Plesiomonas ......................................................... 28330.1 Aeromonas Hydrophila ............................................................................................ 283

30.11 General Characteristic of the Genus............................................................. 28330.12 Ecology ......................................................................................................... 28330.13 Epidemiology ................................................................................................ 28330.14 Isolation Media ............................................................................................. 28530.15 Characterization and Speciation in the Genus Aeromonas ........................... 28630.16 Handling of Samples ..................................................................................... 28730.17 Equipment, Materials, and Reagents ........................................................... 28730.18 Procedures ................................................................................................... 28730.19 Interpretations .............................................................................................. 28830.110 Media, Reagents, and Stains .................................................................... 28830.111 References ................................................................................................ 288

30.2 Arcobacter ............................................................................................................... 29030.21 Introduction .................................................................................................. 29030.22 General Considerations ................................................................................ 29230.23 Media and Reagents ..................................................................................... 29230.24 Procedures ................................................................................................... 29230.25 Identification Tests ....................................................................................... 29330.26 References ................................................................................................... 294

30.3 Plesiomonas Shigelloides ........................................................................................ 29630.31 Introduction .................................................................................................. 29630.32 Ecology ......................................................................................................... 29630.33 Isolation and Identification ............................................................................ 29730.34 Equipment, Materials, and Solutions ............................................................ 29730.35 Procedure ..................................................................................................... 29730.36 References ................................................................................................... 298

| Table of Contents

| ix

Chapter 31 Campylobacter ....................................................................................................... 30131.1 Introduction.............................................................................................................. 30131.2 General Considerations ............................................................................................ 30231.3 Media and Reagents ................................................................................................ 30231.4 Procedures............................................................................................................... 30331.5 Identification Tests ................................................................................................... 30431.6 Interpretation ........................................................................................................... 30731.7 References .............................................................................................................. 307

Chapter 32 Bacillus cereus ....................................................................................................... 31132.1 Introduction.............................................................................................................. 31132.2 Procedure ................................................................................................................ 31332.3 Interpretation of Data ............................................................................................... 31532.4 References .............................................................................................................. 315

Chapter 33 Clostridium botulinum and Its Toxins ................................................................. 31733.1 Introduction.............................................................................................................. 31733.2 Treatment of Specimens ......................................................................................... 31833.3 Special Equipment and Supplies .............................................................................. 31833.4 Media and Reagents ................................................................................................ 31933.5 Precautions and Limitations of Methods ................................................................. 31933.6 Procedure for Identifying Viable C. botulinum ......................................................... 31933.7 Identifying Botulinum Toxin in Foods ....................................................................... 32033.8 Identifying Botulinum Toxin in Clinical Specimens .................................................. 32133.9 Interpreting Data ...................................................................................................... 32233.10 References .............................................................................................................. 323

Chapter 34 Clostridium perfringens ........................................................................................ 32534.1 Introduction.............................................................................................................. 32534.2 Sampling .................................................................................................................. 32634.3 Equipment and Supplies .......................................................................................... 32634.4 Special Reagents and Media ................................................................................... 32634.5 Recommended Controls .......................................................................................... 32734.6 Precautions and Limitations of Methods ................................................................. 32734.7 Procedure ................................................................................................................ 32734.8 Interpretation of Data ............................................................................................... 32934.9 References .............................................................................................................. 329

Chapter 35 Pathogenic Escherichia coli .................................................................................. 33135.1 Introduction.............................................................................................................. 33135.2 Conventional Isolation Procedures .......................................................................... 33235.3 Rapid Methods ........................................................................................................ 33535.4 Serotyping................................................................................................................ 33635.5 Pathogenicity Testing ............................................................................................... 33635.6 References .............................................................................................................. 338

Chapter 36 Listeria .................................................................................................................... 34336.1 Introduction.............................................................................................................. 34336.2 General Considerations ............................................................................................ 34636.3 Media, Reagents, and Equipment ........................................................................... 34636.4 Precautions and Limitations of the Methods ........................................................... 34736.5 Procedures............................................................................................................... 34836.6 Interpretation of Data ............................................................................................... 35336.7 References .............................................................................................................. 353

Chapter 37 Salmonella.............................................................................................................. 35737.1 General Basis of Methods ....................................................................................... 35737.2 Treatment of Sample ............................................................................................... 36437.3 Equipment and Supplies .......................................................................................... 36437.4 Precautions and Limitations of Reference and Rapid Methods............................... 36537.5 Reference Method................................................................................................... 36737.6 Interpretation of DataReference Method ............................................................. 37237.7 Rapid Screening Tests ............................................................................................. 37237.8 AOAC-RI Performance Tested Methods .................................................................. 37537.9 References .............................................................................................................. 376

Chapter 38 Shigella................................................................................................................... 38138.1 Introduction.............................................................................................................. 38138.2 Recommended Procedures ..................................................................................... 382


x |

38.3 Precautions .............................................................................................................. 38438.4 References .............................................................................................................. 385

Chapter 39 Staphylococcus aureus and Staphylococcal Enterotoxins ................................ 38739.1 Introduction.............................................................................................................. 38739.2 General Considerations for Isolation of S. aureus.................................................... 38839.3 Precautions and Limitations of Methods ................................................................. 38939.4 Equipment, Reagents and Media ............................................................................ 39039.5 Procedures............................................................................................................... 39039.6 Additional Tests ....................................................................................................... 39239.7 General Considerations for Detection of Staphylococcal Enterotoxins ................... 39239.8 Handling of Samples ................................................................................................ 39339.9 Examining Staphylococcal Isolates for Enterotoxin Production ............................... 39339.10 Enterotoxin Identification in Foods .......................................................................... 39739.11 References .............................................................................................................. 400

Chapter 40 Vibrio ...................................................................................................................... 40540.1 Introduction.............................................................................................................. 40540.2 General Considerations............................................................................................ 40740.3 Equipment, Materials, and Reagents ....................................................................... 40840.4 Precautions .............................................................................................................. 40940.5 Procedures............................................................................................................... 40940.6 Interpretation ........................................................................................................... 41640.7 Acknowledgment ..................................................................................................... 41640.8 References .............................................................................................................. 416

Chapter 41 Yersinia ................................................................................................................... 42141.1 Introduction.............................................................................................................. 42141.2 Analysis for Yersinia in foods ................................................................................... 42241.3 Yersinia Identification Tests ..................................................................................... 42641.4 References .............................................................................................................. 426

Chapter 42 Waterborne and Foodborne Parasites ................................................................. 42942.1 Introduction.............................................................................................................. 42942.2 Waterborne Parasites: Prevalence, Disease, Transmission,

and Methods of Identification .................................................................................. 43142.3 Foodborne Parasites: Prevalence, Disease, Transmission,

and Methods of Identification .................................................................................. 43442.4 Emerging Methods .................................................................................................. 43742.5 References .............................................................................................................. 437

Chapter 43 Toxigenic Fungi and Fungal Toxins ...................................................................... 43943.1 Introduction.............................................................................................................. 43943.2 Mycotoxins .............................................................................................................. 43943.3 Mycotoxicoses......................................................................................................... 44143.4 Mycotoxin Producing Molds .................................................................................... 44343.5 Equipment, Material, and Reagents ........................................................................ 44443.6 Precautions .............................................................................................................. 44443.7 Media and Procedures ............................................................................................. 44443.8 Reviews and Compendia ......................................................................................... 44543.9 References .............................................................................................................. 445

Chapter 44 Foodborne Viruses ................................................................................................ 44744.1 Introduction.............................................................................................................. 44744.2 Foods To Be Tested ................................................................................................. 44944.3 Detecting Viruses in Foods ...................................................................................... 44944.4 Equipment, Materials and Reagents........................................................................ 45244.5 Sample Processing Procedures ............................................................................... 45244.6 Cell Culture-Based Virus Assays .............................................................................. 45544.7 Virus Identification ................................................................................................... 45644.8 Interpretation of Results .......................................................................................... 45744.9 References .............................................................................................................. 457

Chapter 45 Meat and Poultry Products ................................................................................... 46345.1 Introduction.............................................................................................................. 46345.2 Raw Meat and Poultry Products .............................................................................. 46445.3 Ready-to-Eat Meat and Poultry Products ................................................................. 46645.4 Pathogens ................................................................................................................ 46945.5 Recommended Methods ......................................................................................... 469

| Table of Contents

| xi

45.6 References .............................................................................................................. 469Chapter 46 Eggs and Egg Products ......................................................................................... 473

46.1 Introduction.............................................................................................................. 47346.2 General Considerations ............................................................................................ 47446.3 Normal Flora ............................................................................................................ 47446.4 Flora Changes in Spoilage........................................................................................ 47446.5 Pathogens of Concern ............................................................................................. 47546.6 Indicators of Lack of Sanitation................................................................................ 47646.7 Recommended Methods ......................................................................................... 47646.8 Interpretation of Data ............................................................................................... 47846.9 References .............................................................................................................. 479

Chapter 47 Milk and Milk Products ......................................................................................... 48347.1 Introduction.............................................................................................................. 48347.2 Raw Milk .................................................................................................................. 48347.3 Pasteurized Milk ...................................................................................................... 48447.4 Dried Products ......................................................................................................... 48647.5 Butter ....................................................................................................................... 48647.6 Frozen Dairy Products .............................................................................................. 48747.7 Concentrated Products ............................................................................................ 48747.8 Fermented Dairy Products ....................................................................................... 48847.9 Acid-Producing Bacteria in Dairy Foods ................................................................... 49047.10 Additional Reading ................................................................................................... 49347.11 References .............................................................................................................. 493

Chapter 48 Fish, Crustaceans, and Precooked Seafoods ...................................................... 49748.1 Introduction.............................................................................................................. 49748.2 Fresh and Frozen Fish and Crustaceans .................................................................. 49748.3 Cooked Crustacean Products .................................................................................. 49948.4 Breaded and Prepared Seafood Products ................................................................ 50048.5 Salted and Smoked Products ................................................................................... 50048.6 Other Seafood Products .......................................................................................... 50148.7 Modified-Atmosphere Packaging and Storage ........................................................ 50248.8 Recommended Methods ......................................................................................... 50348.9 Interpretation of Results .......................................................................................... 50348.10 References .............................................................................................................. 504

Chapter 49 Molluscan Shellfish: Oysters, Mussels, and Clams ............................................ 50749.1 Introduction.............................................................................................................. 50749.2 Examination of Shellfish .......................................................................................... 50849.3 Preparation of Sample for Examining Shellfish in the Shell ..................................... 50949.4 Microbiological Procedures...................................................................................... 51149.5 Interpretation of Data ............................................................................................... 51149.6 Rapid Methods ........................................................................................................ 51249.7 International Microbiological Standards ................................................................... 51249.8 References .............................................................................................................. 513

Chapter 50 Fruits and Vegetables ............................................................................................ 51550.1 Introduction.............................................................................................................. 51550.2 Fresh Produce.......................................................................................................... 51550.3 Processed Fruits and Vegetables ............................................................................. 51650.4 Recommended Methods ......................................................................................... 51850.5 Interpretation of Data ............................................................................................... 51850.6 References .............................................................................................................. 518

Chapter 51 Fermented and Acidified Vegetables ................................................................... 52151.1 Introduction.............................................................................................................. 52151.2 Normal Flora ............................................................................................................ 52251.3 Flora Changes in Spoilage........................................................................................ 52251.4 Pathogenic Microorganisms .................................................................................... 52451.5 Recommended Methods ......................................................................................... 52451.6 Interpretation of Data ............................................................................................... 52851.7 References .............................................................................................................. 529

Chapter 52 Gums and Spices ................................................................................................... 53352.1 Introduction.............................................................................................................. 53352.2 General Considerations ............................................................................................ 53352.3 Normal Flora ............................................................................................................ 534


xii |

52.4 Post-Harvest Changes ............................................................................................. 53552.5 Sampling and Preparation for Analysis .................................................................... 53652.6 Methods .................................................................................................................. 53752.7 Interpretation of Data ............................................................................................... 53752.8 References .............................................................................................................. 538

Chapter 53 Salad Dressings ..................................................................................................... 54153.1 Introduction.............................................................................................................. 54153.2 General Considerations............................................................................................ 54153.3 Normal Flora ............................................................................................................ 54153.4 Floral Change in Spoilage......................................................................................... 54153.5 Human Disease Microorganisms............................................................................. 54253.6 Microbial Indicators of Poor Sanitation .................................................................... 54253.7 Equipment, Materials, and Solutions ....................................................................... 54253.8 Recommended Methods ......................................................................................... 54353.9 Interpretation of Data ............................................................................................... 54353.10 References .............................................................................................................. 544

Chapter 54 Sweeteners and Starches ..................................................................................... 54554.1 Introduction.............................................................................................................. 54554.2 General Considerations............................................................................................ 54554.3 Normal and Indicator Flora ....................................................................................... 54654.4 Spoilage Organisms ................................................................................................. 54654.5 Pathogens ................................................................................................................ 54754.6 Recommended Methods ......................................................................................... 54754.7 Interpretation of Data ............................................................................................... 54754.8 References .............................................................................................................. 547

Chapter 55 Cereal and Cereal Products................................................................................... 54955.1 Introduction.............................................................................................................. 54955.2 Factors Affecting Bioload......................................................................................... 54955.3 Methods .................................................................................................................. 55255.4 References .............................................................................................................. 553

Chapter 56 Confectionery Products ......................................................................................... 55556.1 Introduction.............................................................................................................. 55556.2 General Considerations............................................................................................ 55556.3 Spoilage of Confectionery........................................................................................ 55656.4 Pathogens ................................................................................................................ 55656.5 Microbial Control Procedures .................................................................................. 55656.6 Recommended Methods ......................................................................................... 55756.7 Interpretation of Data ............................................................................................... 55756.8 References .............................................................................................................. 558

Chapter 57 Nut Meats ............................................................................................................... 56157.1 Introduction.............................................................................................................. 56157.2 General Considerations............................................................................................ 56157.3 Microflora ................................................................................................................. 56257.4 Pathogens ................................................................................................................ 56257.5 Molds and Mycotoxins ............................................................................................ 56257.6 Laboratory Tests ...................................................................................................... 56257.7 References .............................................................................................................. 563

Chapter 58 Fruit Beverages ...................................................................................................... 56558.1 Introduction.............................................................................................................. 56558.2 Normal Microflora .................................................................................................... 56558.3 Pathogens ................................................................................................................ 56658.4 Spoilage ................................................................................................................... 56658.5 Recommended Methods ......................................................................................... 56658.6 Interpretation of Data ............................................................................................... 56758.7 References .............................................................................................................. 567

Chapter 59 Soft Drinks .................................................................................................................. 56959.1 Introduction.............................................................................................................. 56959.2 Microbiology ............................................................................................................ 56959.3 Sanitation ................................................................................................................. 57059.4 Equipment, Media, and Reagents ........................................................................... 57059.5 Recommended Methods ......................................................................................... 57059.6 Interpretation of Data ............................................................................................... 571

| Table of Contents

| xiii

59.7 References .............................................................................................................. 571Chapter 60 Bottled Water ......................................................................................................... 573

60.1 Introduction.............................................................................................................. 57360.2 Types of Microorganisms ........................................................................................ 57460.3 Equipment, Media, and Reagents ........................................................................... 57460.4 Recommended Methods ......................................................................................... 57460.5 Interpretation of Data ............................................................................................... 57560.6 Acknowledgments ................................................................................................... 57660.7 References .............................................................................................................. 576

Chapter 61 Canned FoodsTests for Commercial Sterility .................................................. 57761.1 Introduction.............................................................................................................. 57761.2 General Considerations ............................................................................................ 57861.3 Equipment, Materials, and Reagents ....................................................................... 57861.4 Precautions .............................................................................................................. 57961.5 Procedure ................................................................................................................ 57961.6 Interpretation of Data ............................................................................................... 58161.7 References .............................................................................................................. 582

Chapter 62 Canned FoodsTests for Cause of Spoilage ...................................................... 58362.1 Introduction.............................................................................................................. 58362.2 Microbiology of Canned Foods ................................................................................ 58362.3 Examination Methods for Diagnosing Spoilage Conditions in Canned Foods ......... 58662.4 Keys to Probable Cause of Spoilage ........................................................................ 59662.5 Addresses for Some Firms Listed in References .................................................... 59662.6 References .............................................................................................................. 596

Chapter 63 Media, Reagents, and Stains ................................................................................ 60163.1 Culture Media, Introduction ..................................................................................... 60163.2 Equipment ............................................................................................................... 60563.3 Alphabetical Listing of Culture Media ...................................................................... 60763.4 Alphabetical Listing of Reagents, Diluents, and Indicators ...................................... 63663.5 Stains, Introduction .................................................................................................. 64663.6 Alphabetical Listing of Stains ................................................................................... 64663.7 References .............................................................................................................. 64863.8 Acknowledgments ................................................................................................... 648

Chapter 64 Measurement of Water Activity (aw), Acidity, and Brix ...................................... 64964.1 Measurement of aw ................................................................................................. 64964.2 Equipment ............................................................................................................... 65064.3 Calibration ................................................................................................................ 65264.4 Measurement of Samples ....................................................................................... 65364.5 Precautions and Limitations..................................................................................... 65364.6 Measurement of Acidity .......................................................................................... 65464.7 pH Measurements ................................................................................................... 65464.8 Titratable Acidity ...................................................................................................... 65664.9 Brix ........................................................................................................................... 65664.10 References .............................................................................................................. 657

Index .................................................................................................................................................. 659


xiv |

About the Editors

Frances Pouch Downes is the director of the Michigan De-partment of Community Health (MDCH) Bureau of Labo-ratories. Until July 1999, she was director of the InfectiousDiseases Division in the Bureau of Laboratories. She has servedas director of the Molecular Biology and Virology laboratories atMDCH. She earned doctorate and masters degrees in laboratorypractice from the University of North Carolina School of PublicHealth. She has a bachelor of science degree in medical technol-ogy from Indiana University. Dr. Downes has worked internation-ally in the laboratory field in Africa, Asia, and the Carribean. Sheis adjunct clinical professor in the Medical Technology Programof Michigan State University.

Keith A. Ito is Senior Vice President of the National FoodProcessors Associations Technical Assistance Center inDublin, California. In this capacity, he oversees the Asso-ciations technical consulting activity at the Center. He has a Bach-elor of Arts degree in Bacteriology from the University of Cali-fornia, Berkeley. He is also Director of the University of CaliforniaLaboratory for Research in Food Preservation, which is adminis-tered by the Food Science and Technology Department at Uni-versity of California, Davis. He has been associated with the Com-pendium as an author, reviewer, and member of the editorialcommittee since the first edition.

Compendium of Methods for the Microbiological Examination of Foods,

Documents

Transcript of Compendium of Methods for the Microbiological Examination of Foods,