Abstract: To purified the isolated E.coli in chickens from different area in Henan, screen phenotype for ESBLs according to NCCLS standards and the double-disc synergy method. Then according to sequences published in GenBank, designed two pairs of primers. The bacteria producing ESBLs were chose, extracted the total DNA, amplified with PCR,cloned, sequenced and analyzed. The results showed the three determinated sequences had 98.9% to 99.7% nucleotide sequence homology with the two reference sequence, amino homology was 98.1% to 99.2%. And there were 15 nucleotide mutations and 6 mutations of amino in the 3 determinated sequences.

Key words: ESBLs gene; clone; sequence analysis