To identify TEM-type and SHV-type ESBLs encoding gene of ESBLs-producing Klebsiella pneumoniae and Escherichia coli, and
to study the evolution and
classification relationships of the ESBLs. Methods The nucleotide sequence of TEM-type and SHV-type ESBLs encoding gene amplified by PCR were detected by automatic sequencer, and the subtypes of the encoding genes were determined by Blastx searching. The relationships of ESBLs molecular evolution and classification were studied by the molecular
evolutionary tree that was constructed by bioinformatics software ClustalX1.8. Results The subtype of ESBLs were SHV-2 and TEM-19 in this study. ESBLs can be categorized into a few types: TEM type, SHV type, OXA type, CTX-M type and other ESBLs. Conclusion The SHV-2 was the main ESBLs in this study. The molecular evolutionary tree constructed in this study can reflect the relationship of ESBLs evolution and classification, and construction of molecular evolutionary tree is a new method for the study of ESBLs classification.