Comparison of two methods for detection ofE. coliO157H7 in unpasteurized milk.
OBJECTIVE
The most common serotype of enterohaemorrhagicEsherichia coligroup or Shiga-toxin-producingE. coliis O157:H7. Domestic and wild ruminants are regarded as the main natural reservoirs. O157:H7 serotype is the major cause of gastrointestinal infections in developed countries. In this study was conducted to survey on the toxigenicE. coliO157: H7 strains in milk of industrial dairy farms.


METHODS
A total number of 150 milk samples were collected from dairy industry in Khuzestan, over a period of 6 months and were evaluated by cultivation in selective media (CT-SMAC) and multiplex PCR.


RESULTS
Two isolates were identified asE. coliusing biochemical tests, none of them were toxigenicE. coliO157:H7 as determined by multiplex PCR. Using direct PCR on milk samples, 45 samples contained at least one gene of the studied genes in this investigation (rfb, flic, stx1,stx2). With direct PCR, 2 milk samples were positive for toxigenic O157:H7.


CONCLUSIONS
E. coliO157:H7 is present in this region and so the necessity for strict compliance of health standards is recommended. This is the first study on O157: H7E. colimilk contamination in Khuzestan province. Based on these results, direct PCR is more accurate than indirect PCR.
Departments of Microbiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Maryam
M
Farahmandfar
Departments of Microbiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Naghmeh
N
Moori-Bakhtiari
Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Saad
S
Gooraninezhad
Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Mehdi
M
Zarei
Escherichia coli O157:H7; Milk; PCR