Title: Certification of a Reference Material with Eschericia Coli O157 (NCTC 12900) at a level of 4 Colony forming Unit per Material Sphere, IRMM-351
Publisher: OPOCE
Publication Year: 2008
JRC N°: JRC48342
ISBN: 978-92-79-10271-4
ISSN: 1018-5593
Other Identifiers: EUR 23540 EN
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC48342
DOI: 10.2787/84342
Type: EUR - Scientific and Technical Research Reports
Abstract: This report describes the certification of a reference material (IRMM-351) of Escherichia coli O157. Certified Reference Materials (CRMs) for microbiological analysis are indispensable tools for development and validation of detection methods and for the implementation and support of internal and external quality control in the area of microbiological analysis. Each vial contains one material sphere of E. coli O157. The homogeneity and stability (at 4 °C, -20 °C and -70 °C) of the batch was assessed by monitoring colony forming units (cfu) on nutrient agr (NA) and eterohemolysin agar (EhlyA) of selected vials by colony counting. The material is not stable at 4 °C but no instability was detected when stored at -20 °C for up to 12 months and at -70 °C for up to 54 months. The batch was characterised by six laboratories to determine a certified value of cfu per vial on NA and EhlyA. The certified value is 4 cfu on both agars with an expanded uncertainty of 2 using a coverage factor k = 2, corresponding to a level of confidence of about 95 %. DNA sequence analysis of the coding region for the fliC gene identified the material as E. coli O157.
JRC Directorate:Health, Consumers and Reference Materials

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