A Afshari - Department of Pathobiology, School of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
M Rad - Department of Pathobiology, School of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
H.A Seifi - Center of Excellence in Ruminant Abortion and Neonatal Mortality and Department of Clinical Sciences,School of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
K Ghazvini - Antimicrobial Resistance Research Center, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

BACKGROUND: Various strains of Escherichia coli (E. coli)are known as major causes of intestinal and extraintestinalinfections in humans and various animal species. Molecularmethods are important for the identification of bacterial isolatesand nucleotide sequence variations, as well as information ontracking bacterial agents related to the outbreaks, the frequencyof the bacterial genetic structure, and the evolution of microbialpopulations. OBJECTIVES: The purpose of the present studywas to evaluate the efficiency of the RAPD method to differentiateE. coli strains. METHODS: In this study, 110 isolates ofE. coli were analyzed by the RAPD PCR method using two10bp oligonucleotides. These strains were isolated from humanswith urinary tract infections and neonatal calves affectedby diarrhea or septicemia. RESULTS: Data analysis showed that87.5% of human E. coli isolates were correctly classified in thehuman host group, while 94.3% of calf E. coli isolates werecorrectly placed in calf groups. It also demonstrated that 100%and 93.3% of isolates were accurately assigned to diarrheic andsepticemic calf groups, respectively. CONCLUSIONS: Geneticvariation analysis indicated that the percentage of polymorphismamong E. coli isolates from humans with urinary tractinfections, diarrheic calves, and septicemic neonatal calveswere 54.71%, 61.22%, and 62.5%, respectively.

E. coli, genetic variation, RAPD PCR