Biochemical positive tests for the isolated Salmonella. A. Triple sugar iron agar (N, negative tube; P, positive with the blackening, and P, positive with the fermentation action with gas production only). B, Lysine iron agar (N, negative tube; P, positive tube with the partial fermentation action, positive tube with the complete fermentation action, and P, positive tube with the blackening. C, Simmons citrate (N, negative tube and P, positive tube with the development of the blue color), D, Methyl red (N, negative tube and P, positive tube with the development of the red color).