Which culture method helps differentiate Escherichia coli O157:H7 from non-O157 strains due to its effect on sorbitol fermentation?

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Multiple Choice

Which culture method helps differentiate Escherichia coli O157:H7 from non-O157 strains due to its effect on sorbitol fermentation?

Explanation:
The main idea is using a differential culture medium that reveals differences in sorbitol fermentation to separate E. coli O157:H7 from other strains. E. coli O157:H7 is typically unable to ferment sorbitol quickly, so on Sorbitol-MacConkey agar these colonies remain colorless (sorbitol nonfermenters). In contrast, most non-O157 E. coli ferment sorbitol and produce acid, causing the colonies to appear pink. This distinct appearance on SMAC makes it the method that differentiates O157:H7 from other strains. The other media won’t reveal this sorbitol fermentation difference.

The main idea is using a differential culture medium that reveals differences in sorbitol fermentation to separate E. coli O157:H7 from other strains. E. coli O157:H7 is typically unable to ferment sorbitol quickly, so on Sorbitol-MacConkey agar these colonies remain colorless (sorbitol nonfermenters). In contrast, most non-O157 E. coli ferment sorbitol and produce acid, causing the colonies to appear pink. This distinct appearance on SMAC makes it the method that differentiates O157:H7 from other strains. The other media won’t reveal this sorbitol fermentation difference.

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