A test that could be used to screen for enterohemorrhagic E. coli

A test that could be used to screen for enterohemorrhagic E. coli

• A. ONPG
• B. MUG
• C. Motility
• D. Growth at 42°C

Answer: (B)

Screening for enterohemorrhagic E. coli relies on a test that flags E. coli among enteric bacteria by detecting β-glucuronidase activity with a fluorogenic substrate. The MUG assay uses 4-methylumbelliferyl-β-D-glucuronide; when β-glucuronidase is present, it hydrolyzes the substrate and emits fluorescence, letting you quickly identify E. coli isolates for further confirmation of virulence genes like stx. Other options aren’t as useful here: ONPG measures β-galactosidase activity and isn’t specific to E. coli; motility is not a distinguishing feature for this purpose; growth at 42°C points more to organisms like Campylobacter rather than E. coli.

Screening for enterohemorrhagic E. coli relies on a test that flags E. coli among enteric bacteria by detecting β-glucuronidase activity with a fluorogenic substrate. The MUG assay uses 4-methylumbelliferyl-β-D-glucuronide; when β-glucuronidase is present, it hydrolyzes the substrate and emits fluorescence, letting you quickly identify E. coli isolates for further confirmation of virulence genes like stx. Other options aren’t as useful here: ONPG measures β-galactosidase activity and isn’t specific to E. coli; motility is not a distinguishing feature for this purpose; growth at 42°C points more to organisms like Campylobacter rather than E. coli.