A new selective and differential culture medium for Salmonella, EF-18 agar, was developed for use with the hydrophobic grid membrane filter (HGMF). The new medium was designed to be both more highly selective and more specific in its differential reactions than its predecessor, selective lysine agar. The HGMF/EF-18 agar method was evaluated against the conventional cultural method (AOAC/BAM) using a total of 954 samples comprising 25 product categories. The HGMF/EF-18 method detected 653 Salmonella-positive samples and the AOAC/BAM method detected 654. The HGMF/EF-18 method with an overall false-negative rate of 2% was determined to be equivalent in sensitivity to the AOAC/BAM procedure. The presumptive false-positive rates were 0.3% for HGMF/EF-18 and 7.9% for AOAC/BAM.

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Author notes

1Present address: Ontario Ministry of Health, Central Laboratories, Toronto, Ontario.