Rapid and sensitive immunomagnetic separation-polymerase chain reaction method for the detection of Escherichia coli O157:H7 in raw milk and ice-cream.

Escherichia coli O157:H7 in spiked samples of raw milk and ice-cream was enriched in tryptic soy broth for 4 h, captured by immunomagnetic separation, subjected to amplification by polymerase chain reaction of parts of the verotoxin genes (SLT-I and SLT-II), and detected by agarose gel electrophoresis. Using this method, as few as 1 cfu Esch. coli O157:H7/g food could be detected in < 10 h.