عنوان مقاله [English]
نویسنده [English]چکیده [English]
Escherichia coli is the natural inhabitant of gastrointestinal tract of animals and also human beings. However, some pathogenic strains of E. coli cause variety of intestinal and extra intestinal diseases. Enterotoxigenic E. coli (ETEC) is the most common cause of diarrhea syndrome in neonatal farm animals and thus is one of the significant causes of economic losses in herds. Fimbriae are the most important factor associated with pathogenicity of ETEC which carry adhesions and work as secretory enterotoxin. The most common fimbriae in calves are F5 (K99) and F41. K99 isolates most commonly belong to serogroups O8, O9 and O101. The objective of this study was to investigate the frequency of genes associated with different serogroups (O8, O9, O101, etc) and K99 fimbriae in fecal samples obtained from calves under 5 days of age. Samples were cultured on MacConkey’s agar, then from each palate, three colonies were cultured separately. Strains were screened for K99 genes and then for O101 by PCR assay, if negative results were obtained, Multiplex PCR was performed to identify genes associated with serogroups O8, O9 and O115. In this study, the frequency of genes associated with O8, O9, O101, O115 serogroups and K99 fimbriae in diarrheic calves were 18.7%, 9.3%, 56.3%, 7.8% and 9.3%, respectively. K99 fimbriae occurred at higher frequencies in O101 serogroup and were detected in 83.3% of those strains.