Isolation and characterization of E. coli O157:H7 from human and animals

This study was conducted to show the importance of Escherichia coli O157:H7 as an important zoonotic pathogen, which has ability to transmit from animals to human in Iraq. One hundred fifty fecal samples (50 stool samples from diarrheal children and 50 from cows and 50 from sheep) were collected for isolation of E. coli O157: H7. All samples were cultured on MacConkey and Eosin Methylene blue agar. Each E. coli growth was confirmed by Gram stain and biochemical tests. Then, all isolated E. coli were sub cultured on Sorbitol MacConkey agar plus cifixime potassium tellurite (SMA-CT). The diagnosis was confirmed by Chrom agar™ E. coli O157:H7 and incubated aerobically at 37 C° for 24 hours. Latex agglutination test was used to all isolates of E. coli O157: H7 to confirm the serotype. The results showed that E. coli were isolated in 40 out of 50 diarrheal children stool samples, where only 2(4%) from these isolates were confirmed as E. coli O157:H7. The number of E. coli isolates from cows and sheep samples were 48 out of 50 and 45 out of 50 respectively, where only 12 (24%) and 10 (20%) isolates were E. coli O157:H7 respectively. The study revealed that most diarrheal cases with positive E. coli O157:H7 were detected in two children aged 1year and 4 years. In conclusion, this study revealed the importance of human and ruminants to act as a reservoir for Escherichia coli O157:H7