Molecular Characterization of E. coli Isolated from Chicken, Cattle and Buffaloes

E. coli plays an important role in maintaining intestinal physiology. However, there are pathogenic strains that cause distinct syndromes of diarrheal disease. In this study we used a collection of 28 E. coli isolated from cattle, buffaloes and chicken obtained in the same geographical area to perform a detailed analysis of the molecular epidemiology of O157 and non O157 strains by using PCR for identifying general similarities and differences in the genetic composition of E. coli populations.The isolates showed a degree of diversity in PCR of stx1, stx2 and eae. 12 strians had stx1 gene, 16 strains had stx2 gene and 10 strains had eae gene. 76.92% of cattle isolates had stx2 and 38.46% possessed both stx1 and stx2, also stx1 was detected from 38.46% of the examined cattle strains. Using restriction enzyme (RE) it is clear that between 3 to 6 fragments were obtained with hindIII digested DNA of chicken and buffalo isolates and between 3 to 5 fragments of cow isolates. Among EcoRI between 5 to 9 fragments were obtained with digested genomic DNA of chicken and cattle and 7 to 9 fragments of buffalo isolates. HindIII and EcoRI ribotyping could reveal only minor differences in non O157:H7 strains belonging to the same serotypes. This indicates that ribotyping which is regarded to be a useful tool for epidemiological investigation, was not able to discriminate between STEC isolates belonging to the same serotype. It is believed that in future a better understanding of moleculer diversity of E.coli strains of different sources would provide and assist the design of approaches to epidemiological studies.