Horizontal method for the detection of Escherichia coli O157
ISO 16654 (2001) method: Escherichia coli O157
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Qualitative process control with RM-EC O.157
- Use a quantitative reference material (RM-EC O.157) with a known number of Escherichia coli serotype O157:H7 (non-VTEC).
- Defrost the material at room temperature for 30 minutes.
- Mix well before use.
- In the case of qualitative operations the contamination level of the reference material (RM-EC O.157) must be representative of the limit of detection.
- At an average contamination level of 5 cfu per control sample, the probability of using a coincidentally uninfected (negative) sample according to the Poisson spread is less than 1%.
- Incubate at (37 ± 1) °C for (21 ± 3) h.
- Determine the absence or presence of the microorganism and register your finding in a qualitative control chart.
- The characteristic reaction is: Transparent colonies with a pale yellowish-brown appearance and a diameter ~1 mm.

Best Practice
The single strain RM-EC O.157 is used for the detection of Escherichia coli O157
Process control detection method
Kind of reference material | Biosisto product for this control method | Control Strain | WDCM number | ||
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Single-strain reference material | Escherichia coli serotype O157:H7 (non-VTEC) | 00014 | |||
The Biosisto reference material in this table is used in the best practice for Qualitative process control according ISO 17025. |