Measuring the capability of immunomagnetic separation-PCR (IMS-PCR) for the detection of one CFU of Escherichia coli O:157 H:7 in milk and soft cheese [electronic resource].

Includes references.

This study was conducted to determine the presence of Escherichia coli O:157 H:7 in raw milk and soft cheese and determination the ability and sensitivity of IMS-PCR method for detection one CFU of this micro¬organism in the same products. A total of 100 samples of raw milk and fresh soft cheese (50 samples of each) were randomly collected from different localities in Bani-suef province and examined according to (Hitchins et al., 2001). Escherichia coli O:157 H:7 was isolated nom 1(2.0%) and 2(4.0%) of the examined raw milk and soft cheese samples, respectively. Milk and soft cheese samples were spiked with E. coli O157 at low levels. The samples were enriched in LB broth and incubated at 37°e. Aliquots of the enriched culture were analyzed either by PCR and IMS-PCR. This study showed that as few as one organism can be detected in 25 ml milk by IMS-PCR method. After 6 h of incubation IMS-PCR were able to detect E. coli from milk but not from cheese samples. After 8 hours of incubation PCR alone was not able to detect any of the samples tested, but IMS combined with PCR was able to detect E. coli in milk and cheeses at low inoculum level. The results indicated that the ability of the IMS to remove inhibiting factors from various food samples is different.

Summary in Arabic.