الفهرس 
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Abstract
Escherichia coli is a significant contributor to calf diarrhea, and its high mortality and slow growth rates have a detrimental economic impact on the global livestock sector. The purpose of the current study was to look at the incidence of E. coli in 120 fecal samples from diarrheic mixed-sex neonatal calves, molecular detection of virulence genes, and antimicrobial resistance testing. The high occurrence of E. coli (90/120; 75%) was detected in diarrheic calves. The molecular detection of virulence genes (iron, papc, asta, iuta, omp, hyl and iuc) showed that the high occurrence of astA (78.8%), iucD (66.6%), and papC (64.4%) genes in examined strains, while only 19 strains devoid of virulence genes.Furthermore, antimicrobial susceptibility testing of E. coli isolates showed absolute resistance to ampicillin (100%), followed by streptomycin (95.5%), tetracycline, sulfonamides, gentamycin and chloramphenicol (77.7% each). In the other hand, strains revealed high rates of susceptibility to ciprofloxacin (80%) and enrofloxacin (77.8%). The multidrug-resistant (MDR) E. coli strains were determined as 77.7% (70/90) and the most identified antimicrobial resistance patterns in 31 strains was C, S, CN, N, TET, AM, SXT. Also, the identified antibiotypes had MAR index values ranged from 0.1 to 0.9.