ISO INTERNATIONAL STANDARD 21528-1 Secondedition 2017-06 Microbiology of the food chain - Horizontal method for the detection and enumeration of Enterobacteriaceae - Part 1: Detection of Enterobacteriaceae Microbiologie de la chaine alimentaire - Methode horizontale par la recherche et le dénombrement des Enterobacteriaceae Partie 1: Recherche des Enterobacteriaceae Reference number IS0 21528-1:2017(E) International Organization for Standardization @ IS0 2017 HEJIANG INST OF STANDARDIZATION C15956617 ed without license from IHS IS0 21528-1:2017(E) COPYRIGHTPROTECTEDDOCUMENT IS02017,PublishedinSwitzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. ISO copyrightoffice Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 [email protected] www.iso.org Intenationaibr PrganizationforStandardization nsee-ZHEJIANG INST OF STANDARDIZzARoISQ 07 - All rights reserved etworking permitted without license from IHS IS0 21528-1:2017(E) Contents Page Foreword ..iv Introduction. ..V 1 Scope. .1 2 Normative references ..1 3 Terms and definitions ..1 4 Principle .2 4.1 Enrichment in non-selective medium .2 4.2 Isolation and selection for confirmation .2 4.3 Confirmation. .2 5 Diluent, culture media and reagent .2 6 Equipment and consumables .2 7 Sampling .3 8 Preparation of test sample .3 9 Procedure 9.1 General .3 9.2 Test portion and initial suspension .4 9.3 Enrichment. 4 9.4 Isolation and selection for confirmation .4 9.4.1 Isolation 4 9.4.2 Selection of colonies for confirmation 4 9.5 Subculturing selected colonies. ..4 9.6 Biochemical confirmation tests 4 9.6.1 Oxidase reaction. ..4 9.6.2 Fermentation test. .5 10 Expression of results .5 11 Precision .5 11.1 Interlaboratory study ..5 11.2 Sensitivity 5 11.3 Specificity .5 12 Test report .5 13 Quality assurance Annex A (informative) Enumeration by MPN technique Annex B (normative) Culture media and reagents ..10 Annex C (informative) Method validation studies and performance characteristics ..15 Bibliography ..17 iii =ZHEJIANG INST OF STANDARDIZATION C15956617 withoutlicense from IHS