• MPN (Most Probable Number): A statistical method using serial dilutions and gas production in lactose broth. Ideal for water and dairy samples with low microbial loads.
• Membrane Filtration (EPA Method 1604): Filters a known volume of water and incubates the membrane on MI agar. E. coli colonies fluoresce under UV light, enabling easy identification.
• Chromogenic/Fluorogenic Substrate Methods: Media like Colilert or Chromocult change color or fluoresce in the presence of E. coli-specific enzymes. These are rapid and suitable for high-throughput labs.
• ISO 16649-2: Uses TBX agar to enumerate β-glucuronidase-positive E. coli. Incubation at 44°C for 24 hours is standard.
• BAM Chapter 4 (FDA): A comprehensive protocol for food and cosmetic testing, including LST-MUG and confirmatory biochemical tests like IMViC.

PCR and Molecular Methods: Detect specific DNA sequences of E. coli. These are highly sensitive and specific, though more resource-intensive.