Abstract
The proficiency testing (PT) scheme “AQUA” for food microbiology was organised by the Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe) according to ISO/IEC 17043 and ISO/TS 22117. This paper describes the IZSVe experience on the application of the above-mentioned standards for the PTs, with focus on the Enterobacteriaceae enumeration one. Freeze-dried food matrices contaminated with American Type Culture Collection bacterial strains were used as test samples for each microbiological PT organised by IZSVe. The sample homogeneity and stability were verified prior to distribution to participants and throughout the PT, respectively. The participating laboratories analysed samples using their routine methods, and results were transmitted to IZSVe. Data and methods used by each participating laboratory were analysed in order to evaluate the laboratory performance. With reference to the Enterobacteriaceae PT, the test samples were homogeneous and stable. In addition, most laboratory results were obtained using equivalent test methods. Statistical approaches applied to analyse data generated from all participating laboratories revealed similar outcomes as no significant outlying count and only 5 % of unacceptable results were observed. Finally, the z-score, with the standard deviation that does not vary from round toround, was applied to compare and to evaluate the performance of each laboratory over time highlighting possible persistent trends over several rounds.
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References
ISO/IEC 17043:2010 Conformity assessment—General requirements for proficiency testing
ISO/TS 22117:2010 Microbiology of food and animal feeding stuffs—specific requirements and guidance for proficiency testing by interlaboratory comparison
ISO 13528:2005 Statistical methods for use in proficiency testing by interlaboratory comparison
Thompson M, Ellison SLR, Wood R (2006) The international harmonised protocol for the proficiency testing of analytical chemistry laboratories. Pure App Chem 78(1):145–196
ISO 21528-2:2004 Microbiology of food and animal feeding stuffs—horizontal method for the detection and enumeration of enterobacteriaceae—part 2: colony-count method
ISO 7218:2007 Microbiology of food and animal feeding stuffs—general requirement and guidance for microbiological examinations
Grimaldi M, Mancin M, Trevisan R, Mioni R (2009) Proficiency testing in food microbiology “AQUA”: enumeration of Staphylococcus aureus. Accred Qual Assur 14:503–505
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Mancin, M., Grimaldi, M., Barco, L. et al. Proficiency testing in food microbiology: experience from implementation of ISO/IEC 17043 and ISO/TS 22117. Accred Qual Assur 17, 425–430 (2012). https://doi.org/10.1007/s00769-012-0904-4
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DOI: https://doi.org/10.1007/s00769-012-0904-4