ISO INTERNATIONAL STANDARD 11731 Second edition 2017-05 Water quality Enumeration of Legionella Qualité de I'eau - Dénombrement des Legionella Reference number ISO 11731:2017(E) International Organization for Standardization See=ZHEJIANG INST OF STANDARDIZATION C1 5956617 @IS02017 vided by IHS under I Not for Resale, 2017/8/21 01:42:59 No reproduction or networking permitted without license from IHS IS0 11731:2017(E) COPYRIGHTPROTECTEDDOCUMENT 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 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. ISOcopyrightoffice 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 Internationai ibrg DrganizationforStandardization icensee-ZHEJIANG INSTOF STANDARDIZAoISQ 07 - All rights reserved Not for Resale, 2017/8/21 01:42:59 networking permited withoutlicense from IHS IS0 11731:2017(E) Contents Page Foreword ..V Introduction. ..vi 1 Scope. 2 Normative references 3 Terms and definitions ..1 4 Principle ..2 4.1 General. .2 4.2 Examination. 4.3 Confirmation ..2 5 Apparatus and glassware .2 6 Culture media and reagents .3 7 Sampling. 8 Procedure ..4 8.1 Samples .4 8.2 Concentration of water samples .5 8.2.1 General. 5 8.2.2 Membrane filtration and direct placing of the membrane filter on culture media 5 8.2.3 Membrane filtration followed by a washing procedure 5 8.3 Sample pre-treatment 6 8.3.1 Heattreatment .6 8.3.2 Acid treatment 6 8.4 Culture ..6 8.4.1 General. ..6 8.4.2 Samples with a high concentration of Legionella species and a low concentration of interfering microorganisms .6 8.4.3 Samples with a low concentration of Legionella species and a low concentrationofinterferingmicroorganisms .6 8.4.4 Samples with a high concentration of interfering microorganisms 8.4.5 Samples with an extremely high concentration of interfering microorganisms... 8.4.6 Incubation. 8.4.7 Examination of the plates. 8.5 Confirmation of presumptive Legionella colonies on culture media: BCYE agar and BCYE-cys agar. .8 9 Expression of results. ..8 10 Test report ..9 11 Quality assurance .10 11.1 General .10 11.2 Performance testing of Legionella culture media .10 11.3 Preparing working culture and test suspension for performance testing ..10 Annex A (informative) Legionella species ..12 Annex B (normative) Culture media ..14 Annex C (normative) Diluents ..20 Annex D (normative) Acid solution ..21 Annex E (informative) Scraping or rubbing the bacteria from membrane filters ..22 Annex F (informative) Centrifugation technique ..23 iii icensee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 ed without license from IHS Not for Resale, 2017/8/21 01:42:59