Detection of E. coli toxin and virulence genes commonly associated with pathogenic strains of E. coli: F4/K88 fimbrial adhesins, STa enterotoxin, LT enterotoxin, CNF1 and CNF2 cytotoxic necrotizing factors, Stx1 and Stx2 Shiga like toxins, and eaeA intimin in E. coli isolates by real-time PCR (rtPCR).