Colibacillosis is a fetal and serious problematic disease particularly in young calves during
the first days of their life accompanied with high mortality losses. The aim of this study is
to moleculary characterize Escherichia coli (E. coli) strains isolated from individual cases of
neonatal calf diarrhea. Characteristic clinical symptoms as yellowish diarrhea with low
colostrum feeding history was observed during samples collection. Rectal swabs were
obtained from 50 healthy and 100 clinically infected diarrheic calves which identified by
traditional bacteriological and serological procedures. Then, E. coli isolates were subjected
for genetic characterization of virulence genes (stx1, stx2, fimH, iutA, eaeA and tsh) using
both uniplex and multiplex PCR. The most dominant virulence gene was fimH in all the
examined isolates followed by iutA in 50% however, the eaeA and tsh genes were in 37.5%
while no detection for both stx1 and stx2 genes. In conclusion, these results provide
updated information regarding the molecular detection of E. coli strains from neonatal
calves in Egypt and thus, would be important to formulate preventing tools and effective
therapy against E. coli either in Egypt and or worldwide.