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Figure 1: Salmonella enterica on Hektoen enteric agar. Note the black center of the transparent colonies, indicating H2S production in the absence of carbohydrate fermentation. All serotypes of Salmonella have this appearance on Hektoen enteric agar except for serotype Typhi, which is a weak H2S producer. (Jan Hudzicki, University of Kansas Medical Center, Kansas City, KS)

Figure 2: Shigella flexneri on Hektoen enteric agar. Note the transparent colonies, indicating the absence of carbohydrate fermentation. The lack of black colonies indicates no H2S production. All species of Shigella have this appearance on Hektoen enteric agar. (Jan Hudzicki, University of Kansas Medical Center, Kansas City, KS)

Figure 3: Enterobacter aerogenes on Hektoen enteric agar. Note the yellow-orange colonies, indicating the fermentation of at least one of the carbohydrates present in the medium. The lack of black colonies indicates no H2S production.  The orange haze around the colonies is due to the precipitation of the bile salts by the organism.  The appearance of E. aerogenes on Hektoen enteric agar is typical of most nonpathogenic enteric gram-negative rods. (Jan Hudzicki, University of Kansas Medical Center, Kansas City, KS)

Figure 4: Proteus vulgaris on Hektoen enteric agar. Note the yellow-orange colonies, indicating the fermentation of at least one of the carbohydrates present in the medium. The lack of black colonies indicates no H2S production. The lack of orange haze around the colonies indicates there is no precipitation of the bile salts by this organism. (Jan Hudzicki, University of Kansas Medical Center, Kansas City, KS)

Figure 5: Stool culture on Hektoen enteric agar: mixed flora including Escherichia coli (normal flora), Salmonella, and Proteus vulgaris. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 6: Stool Culture on Hektoen Enteric Agar (Labeled). Stool culture on Hektoen enteric agar: mixed flora including Escherichia coli (red arrow), Salmonella (blue arrow), and Proteus vulgaris (yellow arrow). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 7: Stool culture on Hektoen enteric agar: Salmonella mixed with normal fecal flora. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 8: Stool culture on Hektoen enteric agar: normal fecal flora. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 9: Stool culture on Hektoen enteric agar: heavy growth of Salmonella mixed with another non-lactose-fermenting fecal organism. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 10: Stool culture on Hektoen enteric agar: Shigella sonnei mixed with normal fecal flora. (Rebecca Buxton, University of Utah, Salt Lake City, UT)