Pure colonies that showed typical black or gray coloration on Rainbow agar were inoculated on BUG (Biolog Universal Growth Medium) agar (Hayward, USA) with 5% sheep blood and incubated at 37°C for 24 hrs. Subculture was made using the same culture media to have pure culture colonies before identification was done by OmniLog. The BUG is a recommended medium for aerobic bacteria and it was employed to isolate E. coli. Following this, the identification of E. coli O157:H7 was performed using the Omnilog plus Identification System (BiOLOG User Guide 2008)