Molecular characterization of enterotoxigenic Escherichia coli isolated from neonatal calves diarrhea

Enterotoxigenic Escherichia coli (ETEC) produces different virulence factors allowing the bacterium to colonize and develop watery diarrhea. Proteomics studies have also introduced new protein belonging to the secretion pathways, antigen ۴۳ (Ag۴۳), which plays important role in E. coli pathogenesis. The objective of this study was to investigate O-types and virulence factors of E. coli isolates from neonatal calves diarrhea. Total of ۱۲۰ isolates from diarrheic calves were genotyped for their O groups and the presence of virulence genes K۹۹, F۴۱ and STa as well as Ag۴۳. The predominant O-type was O۱۰۱ (۵۱.۰۰%) and the prevalence of K۹۹, F۴۱ and STa was ۷ (۵.۸۰%). The Ag۴۳ was detected in all samples with three different allelic patterns. Our results indicated that K۹۹ positive isolates certainly have one of each ۲۲۰۰ bp or ۱۸۰۰ bp or both copies of Ag۴۳ passenger domain, while negative K۹۹ isolates lack the Ag۴۳. The results reported here provide informative data regarding the prevalence of E. coli O-types and their virulence factors in enteric colibacillosis. The Ag۴۳ that was more found in K۹۹ positive isolates might be associated with diarrhea-causing E. coli strains in neonatal calves.

Keywords:

Antigen ۴۳ , Calf , Diarrhea , Entrotoxigenic Escherichia coli , O-type