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HomeCertification of a reference material with Enterococcus faecalis (CIP 106877) at a target level of 1000 colony forming units IRMM-355
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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. IRMM already offers microbiological reference materials (RMs) with certified colony forming unit (cfu) numbers per capsule covering six different food and water micro-organisms (http://irmm.jrc.ec.europa.eu). Measurement effects, such as Poisson distribution at low cfu counts, encouraged us to consider alternative approaches for development and certification of reference materials. The production of freeze-dried BioBallsTM is not based on aliquoting but rather on transferring a counted number of bacterial or yeast cells into a single BioBallTM with a modified flow cytometer [1]. The IRMM's portfolio of CRMs in the BioBallTM format currently consists of two low cfu materials (IRMM-351, containing E. coli O157 and IRMM-352, containing S. enteritidis) and one material at a target level of 1000 cfu (IRMM-354, containing C. albicans). IRMM currently extends the range of these CRMs to more micro-organisms at a level of 1000 cfu per material sphere for water control laboratories. Enterococcus faecalis is a gram-positive, opportunistic bacterium that inhabits the gastrointestinal tracts of humans and many animals. Because of their ability to acquire high-level resistance to antimicrobial agents, enterococci have emerged as nosocomial pathogens worldwide. Enterococcus faecalis causes 80 to 90% of human enterococcal infections [2, 3]. This report describes the certification of a batch of 1000 vials (IRMM-355) containing E. faecalis at a target level of 1000 cfu per material sphere. Homogeneity and stability of the produced batch were analysed at IRMM following in house procedures applying a quality management system according to ISO Guide 34 [4-7]. Batch characterisation was performed by IRMM and five external laboratories. The methods used for the batch characterisation as well as for homogeneity and stability testing were colony counting on Horse Blood Agar (BA) and Slanetz and Bartley agar (SB agar) according to ISO 7218 [8] and ISO 7899-2 [9] respectively. BA is Columbia agar containing 5 % horse blood and is used as a non-selective growth agar. SB agar is a selective growth agar for the detection and enumeration of intestinal enterococci in surface and waste water. Identification of E. faecalis was performed by DNA sequence analysis of the efaA gene encoding the endocarditis antigen [10].
- Published:
- Corporate author(s): Institute for Reference Materials and Measurements (Joint Research Centre)
- Personal author(s): Baets, L. de ; Meeus, N ; Schimmel, H
- Themes: Medical and biological research
- Subject: biological standard , biology , Community certification , gastrointestinal disease , microorganism , research body , research method
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| ISSN 1018-5593 | ISBN 978-92-79-12811-0 | DOI 10.2787/11105 | Catalogue number LA-NA-23938-EN-C |
- Released on EU publications website:
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