A COMPARISON OF 6 DIFFERENT PLATING MEDIA USED IN THE ISOLATION OF SALMONELLA

Seventeen Canadian Federal, Provincial and Public Health Laboratories took part in different phases of a comparative/collaborative study tha t evaluated rapid methods to the standard Health Protection Branch (HP B) method for the detection of Salmonella. A variety of commercial med ia were tested, including Brilliant Green Sulpha Agar, Bismuth Sulphit e Agar, Hektoen Enteric Agar, Xylose Lysine Deoxycholate Agar, EF-18 A gar and Rambach Agar. Each laboratory compared up to six of these diff erent plating media. Plating of 123 salmonellae cultures and 28 artifi cially-inoculated foods showed the recovery of Salmonella spp. on the six plating media to be within one log. Therefore, quantitative testin g of the media showed them to be comparable in the recovery of salmone llae. Qualitative testing of the six media during the comparative/coll aborative study of various methods showed that EF-18 Agar recovered th e greatest number of isolates. Hektoen Enteric Agar ranked second, wit h the other agars being comparable in their recovery of Salmonella spp . Problems with the various media are summarized. Based on our results and those of other researchers, it is recommended that Bismuth Sulphi te Agar be compulsory and that at least one other agar be used for new ly developed cultural procedures.