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Abstract

Neonatal calf diarrhea is one of the most important problems facing livestock causing great economic losses. E. coli is one of the most dangerous pathogens induced neonatal calves diarrhea from birth until about 3 months of age. This study investigated the prevalence of E. coli infection in diarrheic calves in middle Egypt Governorates (Giza, El Fayoum and Beni-Suef) to determine the virulence gene markers for E. coli isolates; using multiplex-PCR, detecting their pathotypes especially ETEC. Fecal samples were collected from 58 cross breed diarrheic calves up to 3 months and 38 E. coli isolates were recovered with prevalence of 65.5%. The highest prevalence was recorded in El-Fayoum (71.4%), followed by Giza (66.7%) while the lowest prevalence was Beni-Suef (57.1%). Serogrouping of E. coli isolates showed that 10 O-serogroups were identified. The serogroup O26 was the most prevalent (21.1%) followed by O103 (18.4%) then, serogroups O86 and O111 (13.2% and 10.5%, respectively). Moreover, other serogroups were recorded; O119, O127 and O157 (5.3% for each) and O18, O44 and O158 (2.6% for each) while, 13.2% of E. coli isolates were untyped. Analysis of multiplex PCR results for different E. coli serotypes showed that ETEC, AEEC, EHEC genes were possessed in 70%, 70% and 30% of isolates, respectively while none of the isolates possessed STEC gene. The in in-vitro susceptibility testing of E. coli isolates was applied. Mostly, E. coli isolates showed high resistances against the majority of antimicrobials used while; high sensitivity was observed to neomycin only.