Proposal on interlaboratory comparison study on detection of Salmonella in food/animal feed 2012 Angelina Kuijpers
Detection study design Current set-up in general: 34 samples Lenticule discs Control Test samples samples No matrix With matrix Salmonella serovar 1 low 2 5 Salmonella serovar 1 high 1 5 Salmonella serovar 2 low 2 5 Salmonella serovar 2 high - 5 Blank 2 5 Procedure control 2 - Total samples 9 25 2
Detection study We receive regularly questions why studies have to be so large Is it possible to organise it differently still obtaining statistical valid data? Have a look in literature available ISO docs 3
ISO docs for Proficiency Testing ISO 22117 (2010): Microbiology of food & animal feedingstuffs - Specific requirements & guidance for Proficiency Testing (PT) by interlaboratory comparison In ISO 22117 reference is made to ISO 17043 and ISO 13528 ISO 17043 (2010): General requirements for organisation of Proficiency Testing (PT) ISO 13528 (2005) : Statistical methods for use in Proficiency Testing by interlaboratory comparisons 4
ISO 22117: Microbiology of food & animal feedingstuffs Scope: Food & beverages Animal feeding stuffs Food production environments & food handling Primary production stage Relates to the technical organization and the implementation of proficiency testing schemes, as well as the statistical treatment of the results of microbiological examinations. 5
ISO 22117: Microbiology of food & animal feedingstuffs 8.4 Assessment of qualitative methods As the result of a precense/absence test is a yes/no, many samples need to be tested in order to assess the performance of the individual laboratories in a PT scheme. Each participant should test at least 18 samples in total. Six replicates of three different levels of contamination of the samples - Negative samples x6 : all samples should be found negative - Low level samples x6 : it can be calculated (e.g. best estimate from the results of all participants) - High level samples x6 : all samples should be tested positive 6
Study design : number of samples Lenticule discs Control samples No matrix Test samples With matrix Salmonella serovar 1 low 2 2 2 5 6 6 Salmonella serovar 1 high 1 1 1 5 6 6 Salmonella serovar 2 low 2-2 5-6 Salmonella serovar 2 high - - 1 5-6 Blank 2 2 2 5 6 6 Procedure control 2 2 2 - - - Total samples 9 7 10 25 18 30 Number of samples Current studies 2 serovars: 9 + 25 = 34 New proposal According ISO 22117 : 1 serovar 7 + 18 = 25 2 serovars 10 + 30= 40 7
Proposal Food/animal feed study 2012 Proposal : animal feed - Is part of the workfield of EURL and NRLs - Up to now only 1 study on animal feed organised in 2008 Choices to make: - Matrix - Serovar. 8
Proposal Food/animal feed study 2012 Choices to make: Matrix - Ingredient e.g. Soya? - Or complete animal feed? - Suggestions? 9
Proposal Food/animal feed study 2012 Choices to make serovar.: - Soy Bean isolates mentioned in EFSA animal feed opinion 2008 & EFSA Zoonose report 2010 : Cubana, Indiana, Senftenberg, Mbandaka, Tennessee & Infantis - Do we want to test another serovar than SE or STM? e.g. S. Infantis (= part of top 5) Mind: choice serovar will depend on ability of HPA to prepare batches of lenticule discs in time 10
Proposal animal feed study 2012 September/October 2012 (final scheme in August) Matrix : Soya? Number of samples : 25 / 34 / 40? Methods : Prescribed ISO 6579 (RVS, MKTTn/ XLD, 2nd agar) Requested Annex D of ISO 6579 (MSRV/ XLD, 2 nd agar) Optional: Own (e.g. PCR) Evaluation comparable to earlier studies 11
Further optimisation detection studies Review test report Filter out most relevant questions in the test report Most questions have been helpffull to find possible clarifications in case of underperfromance However, NRLs are accredited according ISO 17025 -All relevant info should also be availabale in their system -May be possible to delete several questions from test report Currently reviewing possibilities for web based test reports 12
Proposal for the next detection studies Less samples with only one serovar Shorter test report Web based test report 13
THANK you for your attention Angelina Kuijpers 14