Eleventh CRL-Salmonella interlaboratory comparison study (2006) on typing of Salmonella spp.

The eleventh interlaboratory comparison study on the typing of Salmonella was organised by the Community Reference Laboratory for Salmonella (CRL-Salmonella, Bilthoven, The Netherlands) in collaboration with the Health Protection Agency (HPA, London, United Kingdom) in March 2006. 26 National Reference Laboratories for Salmonella (NRLs-Salmonella), including Norway, and 31 Enter-Net Laboratories (ENLs), three of which also NRLs, participated in the study. In total, 20 strains of the species Salmonella enterica subspecies enterica were selected for serotyping. 10 strains of Salmonella Enteritidis (SE) and 10 strains of Salmonella Typhimurium (STM) were selected for phage typing. In general, no problems were encountered with the typing of the O-antigens. 98 % of the NRLs and 98 % of the ENLs were able to correctly type the O-antigens. A few laboratories had problems typing the H-antigens. The H-antigens were typed correctly by 94 % of the NRLs and by 94 % of the ENLs. 93 % of the NRLs and 93 % of the ENLs indicated correct serovar names for the 20 serotyping strains. The phage typing results of the majority of the NRLs were found to be good. The seven NRLs phage typed 94 % of the Salmonella Enteritidis strains correct and 99 % of the Salmonella Typhimurium strains. 18 ENLs participated in the phagetyping. The Salmonella Enteritidis strains were correctly phage typed by 84 % of the ENLs and Salmonella Typhimurium by 89 % of the ENLs