ISO INTERNATIONAL STANDARD 11290-2 Secondedition 2017-05 Microbiology of the food chain Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp. - Part 2: Enumeration method Microbiologie de la chaine alimentaire - Méthode horizontale pour la recherche et le dénombrement de Listeria monocytogenes et de Listeria spp. Partie 2: Methode de dénombrement Reference number ISO 11290-2:2017(E) International Organization for Standardization @ IS0 2017 ZHEJIANG INST OF STANDARDIZATION C1 5956617 ed without license from IHS IS0 11290-2:2017(E) COPYRIGHT PROTECTED DOCUMENT IS0 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form 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 copyright office Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org Internatinir DrganizationforStandardization licensee-ZHEJIANG INST OF STANDARDIZzRoISQ7 - All rights reserved Not for Resale, 2017/8/21 01:39:48 No reproduction or networking permited without license from IHS IS0 11290-2:2017(E) Contents Page Foreword ..iv Introduction. .. 1 Scope. ..1 2 Normative references 3 Terms and definitions .2 4 Principle .2 4.1 General .2 4.2 Initial suspension. .2 4.3 Surface plating. .2 4.4 Incubation. .2 4.5 Confirmation 3 4.6 Enumeration 3 5 Culture media and reagents ..3 6 Equipment and consumables ..3 7 Sampling. ..3 8 Preparation of test sample ..4 9 Procedure .4 9.1 Test portion, initial suspension and dilutions 9.2 Inoculationandincubation .4 9.3 Enumeration of characteristic colonies 4 9.4 Confirmation of L. monocytogenes or Listeria spp 5 9.4.1 Selection of colonies for confirmation 5 9.4.2 Confirmation of L. monocytogenes .6 9.4.3 Confirmation of Listeria spp. .9 9.5 Interpretation of morphological and physiological properties and of the biochemical reactions ..10 9.6 Additional characterization of isolated strains (optional) .10 10 Expression of results ..10 11 Performance characteristics of the method. ..10 11.1 Method validation study .10 11.2 Repeatability limit ..11 11.3 Reproducibility limit .11 12 Test report .11 13 Quality assurance ..12 Annex A (normative) Diagram of procedure ..13 Annex B (normative) Composition and preparation of media and reagents ..14 Annex C (informative) Distinction of Listeria spp. from other genera ..22 Annex D (informative) Reactions for the identification of Listeria species ..23 Annex E (informative) Results of interlaboratory studies for enumeration of Listeria monocytogenes.. .25 Bibliography .28 ii icensee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 d without license from IHS Not for Resale, 2017/8/21 01:39:48