Abstract: From Jan 1996 to May 1999,the antimicro bial susceptibility of Escherichia coli and Klebsiella pnenumoniae to ceftazidime(CAZ), aztreonam(AZT), cefotaxime(CTX), ceftriaxone(CRO) and imipenem(IMP) were tested.The minium inhibitory concentration(MIC) testing from Jan 1996 to May 1999 was made for the antimicrobial suscepitibility of E.coli and K. pneumoniae; the Disk diffusion from May 1999 to Oct 1999 was tested for ESBLs in E.coli and K.pneumoniae.The results showed: ① the susceptibility in AZT increased; ② the susceptibility in CAZ, IMP was still strong; ③ the susceptibility of K.pneumoniae to CAZ, CTX, CRO in 1999 decreased obviously; ④ through the method of K-B, it was found that the rate of ESBLs pro duction in E. coli and K. pneumoniae in 1999 is 23.1%(21/88), the rate of K.pneumoniae in these 21 ESBLs-producing becteria is 61.9%(13/21), which is much higher than that of E.coli(38.1%, 8/21).

Key words: E.coli, K.pneumoniae, antibiotic, extended-sepctrum β-lactamases (ESBx)