ISO INTERNATIONAL STANDARD 10273 Third edition 2017-03 Microbiology of the food chain Horizontal method for the detection of pathogenic Yersinia enterocolitica Microbiologie de la chaine alimentaire Methode horizontale pour la recherche de Yersinia enterocolitica pathogenes Reference number IS0 10273:2017(E) so International Organization for Standardization @ IS0 2017 =ZHEJIANG INST OF STANDARDIZATION C1 5956617 mitted without license from IHS IS0 10273:2017(E) Contents Page Foreword ..V Introduction. ..vii 1 Scope. 2 Normative references 3 Terms and definitions 4 Abbreviated terms ..2 5 Principle .2 5.1 General .2 5.2 Direct plating from liquid enrichment medium 2 5.3 Enrichment in liquid enrichment medium and selective liquid enrichment medium 2 5.4 Plating out after enrichment and identification. . 2 5.5 Confirmation. .3 6 Culture media and reagents .3 7 Equipment and consumables .3 8 Sampling. .3 9 Preparation of test sample .4 10 Procedure (as shown in Annex A) .4 10.1 Test portion and initial suspension .4 10.2 Direct plating on selective agar. .4 10.3 Enrichment. .5 10.4 Plating out and incubation of plates .5 10.4.1 Plating from PSB and ITC by KOH treatment on CIN agar. 5 10.4.2 Plating from PSB and ITC by KOH treatment on chromogenic agar (optional) 5 10.5 Identification of characteristic colonies. 5 10.6 Confirmation .6 10.6.1 General .6 10.6.2 Selection of colonies for confirmation .6 10.6.3 Determination of pathogenic Yersinia species .6 10.6.4 Confirmation of pathogenic Y. enterocolitica .8 10.6.5 Interpretation of confirmation tests for Y. enterocolitica. .10 10.6.6 Interpretation of confirmation tests for pathogenic Y. enterocolitica 10 10.7 Biotyping of Y. enterocolitica (optional) ..10 10.7.1 General. .10 10.7.2 Fermentation of xylose .11 10.7.3 Tween-esterase test .11 10.7.4 Fermentation of salicin (optional) and trehalose. .11 10.7.5 Indole formation ..11 10.7.6 Interpretation of biotyping tests .11 11 Expression of results ..12 12 Performance characteristics of the method. ..12 12.1 Interlaboratory study ..12 12.2 Sensitivity ..12 12.3 Specificity ..12 12.4 LOD50 ..12 13 Test report. ..12 14 Quality assurance ..13 Annex A (normative) Diagrams of the procedures ..14 iii icensee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 ed without license from IHS