Abstract
Shiga toxigenic Escherichia coli O157: H7 and O111 are capable of causing severe gastrointestinal disease in humans and animals. The present study aims to detect and characterizes E. coli O157:117 and O111 in the milk samples collected from cattle with clinical and subclinical mastitis. Out of 240 examined milk samples, 48 E.coli isolates (20%) obtained clinical mastitic cases, while, 22 (13.75%) out of 160 examined milk samples obtained from subclinical mastitic animals. 22 strains (19.7%) O111, 12 strains (5%) O157: 117, 8 strains (3.33%) O128 and 6 strains (2.5%) O119 were recovered from clinical mastitic cases. While serotyping of E. coli received from subclinical mastitis revealed, 11 strains (6.87%) O111, 5 strains (3.13%) O157: 117, 4 strains (2.5%) 0128 and 2 strains (1.25%) O119. Multiplex PCR using 0157 and O111 primers revealed the ability detect all the bacteriologically posiaive samples. Moreover, the multiplex PCR could detect 7 strains of E. coli O111 and 5 strains of O157 from animals with subclinical mastitis, such samples were proved to be negative for O157 and O111 by bacteriological examination which indicated the ability of the serolroupOspecific multiplex PCR assay to detect a very low concentration by STEC organisms.