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MolecularREF 5123222701
Organism · Solutions
Escherichia coli testing
E. coli sits in two roles at once — a faecal indicator that signals process hygiene failure, and, in its pathogenic serotypes, a hazard in its own right. Which role you are testing for changes the method entirely.
Indigo-blue colonies · chromogenic agarWhy Escherichia coli testing is demanding
Most routine E. coli testing is indicator testing: its presence signals faecal contamination and, by extension, a failure somewhere in process hygiene or water quality. In that role it is enumerated rather than merely detected, and the count itself is the result that matters.
The separate and more serious case is pathogenic E. coli — O157:H7 and other STEC serotypes — where the requirement is absence rather than a count, and where the testing workflow resembles Salmonella more than it resembles indicator enumeration. Conflating the two is a common source of specification error.
For the indicator role, chromogenic media have largely replaced older confirmation-heavy workflows: β-glucuronidase-based substrates give a countable, visually unambiguous result at 24 hours. For the pathogenic role, enrichment followed by molecular confirmation is the practical route, because the detection level required is far below what direct plating resolves.
- Indicator role
- Enumeration
- Pathogenic role
- Absence in 25 g
- Reference method
- ISO 16649-2
- Result
- 24 h chromogenic
Methods compared
Indicator enumeration and pathogen detection are different problems — these are the routes to each.
- Traditional · ISO 16649-2Commonly used culture media
TBX Agar, MacConkey Agar and Chromocult Coliform Agar are commonly used to screen, differentiate and enumerate E. coli in routine culture-based testing.
Time to result24 h - RapidReady-to-use counting
Ready-to-use plate formats for high-volume routine enumeration, removing media preparation from the workflow while keeping the count comparable to reference methods.
Time to result24 h - Molecular · Real-time PCRSTEC and O157 detection
Real-time PCR for pathogenic serotypes after enrichment, where the requirement is absence at low levels rather than a count.
Time to resultSame day, post-enrichment
Confirm which role your specification means before selecting a method.
Ask usProducts for Escherichia coli testing
A selection spanning culture media, rapid formats and molecular assays. The full range is in the catalogue.
Standards & compliance
The references an E. coli programme is measured against.
- ISO 16649-2
- Horizontal method for the enumeration of β-glucuronidase-positive Escherichia coli — colony-count technique at 44 °C.
- ISO 16654
- Horizontal method for the detection of Escherichia coli O157, applied where the pathogenic serotype is specified.
- AOAC validation
- Rapid enumeration plates and molecular STEC assays carry AOAC validation; confirm the validation matches the role you are testing for.
- SFDA
- Supplied through an SFDA-licensed establishment, aligned to Kingdom requirements for the matrices you test.
Sourced from the brands your methods are built on.
Testing for Escherichia coli?
Tell us your matrix and how fast you need a release decision — we'll recommend the method and respond with pricing, availability and lead time.