Clinical and molecular study of E. coli O157:H7 isolated from Diarrheic and non-diarrheic dogs

A clinical study was performed on 104 dogs and puppies with different ages, breeds and sexes. The molecular study was conducted to confirm E. coli O157:H7 which was isolated from these animals using a real-time PCR for detection of rfb O157 and flic H7 genes. Totally, eighty seven E. coli isolates were isolated from 104 fecal samples by the traditional methods of culturing (on initial enrichment media, gram stain and biochemical tests). From 87 E. coli isolates, 26 isolates were belonged to E. coli O157:H7, when were cultured on specific media the Chrom agar O157. Only 18 (17.3%) isolates were positive for both O157 and H7 antigens, however, only 8 samples were positive to O157 antigen by latex agglutination test. The results of the real time PCR on 26 isolates showed that 7 (26.92%) were having rfb O157 gene, 18 (69.23%) were possessed rfb O157 and flic H7 genes, while only one (3.85%) was negative for both genes. The 18 animals which were positive for bacterial isolation, showed different clinical signs including: fever, increase respiration and heart rates, diarrhea. Dehydration and congested mucous membrane were seen in 11 animals, while the rested 7 animals didn’t showed any clinical signs. Females were more susceptible than male for infection with E. coli O157:H7. The results of this study showed also that the global breed were more infected than the local breed. In addition, puppies at age 1-2 months were most susceptible. In conclusion, this study reveals that E. coli O157:H7 is important pathogen in dogs and the real time PCR is approved as a best, reliable and faster method for confirmatory diagnosis of these strains