A total of 102 chicken samples were collected from different farms in Qalubia, Behera, Cairo, Assuit and Menofia
Governorates. The samples were represented by liver, spleen, lungs, heart blood, intestine and kidneys and subjected for
isolation and identification of Escherichia coli. The bacteriological examination of the samples indicated the isolation of
55 E. coli represented as 31, 6, 8, 5, and 5 from Qalubia, Behera, Cairo, Assuit and Menofia, respectively. Different
serotypes of E. coli (O₁₅₈, O₁₂₅, O₁₁₁, O₂₇, O₂₀, O₆, O₂₅, O₂₆, O₁₄₅, and O₁₅₉) and12 untyped strains were demonstrated.
Thirty-Two E. coli isolates were subjected to initial screening test for extended-spectrum beta-lactamases (ESBLs)
production by disc diffusion method with various cephalosporins. The results showed that 46.9% of samples were
sensitive to ceftriaxone and cefotaxime and 53.1% to ceftazidime. By double disc synergy test, 19 E. coli strains were
identified as ESBL producers. PCR results of 32 E. coli isolates showed that blaTEM gene was detected in the genomic
DNA of all isolates and in plasmid DNA of 18 isolates. While, blaSHV was detected in the genomic DNA of 12 isolates
and in plasmid DNA of 9 isolates. We can conclude from the current results that amplification of both genomic and
plasmid DNA increase the positivity of detection in comparison with amplification of each of DNAs alone