Results of Salmonella enterica subsp. enterica serotype identification by Salmonella Check&Trace microarray in international External Quality Assurance Systems.

Abstract

Introduction: Traditionally Salmonella enterica subsp. enterica serotypes are identified by slide agglutination with specific antisera for somatic, flagellar and sometimes capsular antigens. An alternative way is genoserotyping using for example a microarray, eg. commercially available test Check&Trace Salmonella. The goal of this study was to evaluate the Check&Trace Salmonella microarray for Salmonella enterica subsp. enterica serotype identification, using Salmonella strains provided by reference laboratories during External Quality Assurance Systems organized for national reference laboratories by ECDC and WHO GFN.

Material and methods: 80 Salmonella enterica subsp. enterica have been tested using Check & Trace Salmonella (Check-Points BC, Netherlands). Also classical slide agglutination was performed according to EN ISO 6579:2003/Al:2007 norm, used as reference method.

Results: In the group of 80 tested strains, 66% were identified correctly, 4% gave uncertain results and 29% showed "Salmonella, genovar" without a serotype, of which 69% were not included in the CTS list of serotypes. Finally one strain has been recognized incorrectly.

Discussion: Because of IVD certification lack, the CTS test could not be recommended to clinical laboratories. AOAC-RI and OIE certification for test cause, that CTS could be used in most food, environmental and veterinary laboratories with the condition, that all unrecognized strains should be sent to a reference laboratory, to type according to EN ISO 6579:2003/Al:2007 norm, by KWM serotyping or other equal alternative methods.