Study on extended-spectrum β-lactmases genotype in gram-negative bacilli

  Objective   To study the ex tended-spectrum B-lactamases (ESBLs) geno type in gram-negative bacilli.

  Methods   All of the ESBLs were screened by double disk synergic test and subjected to drug suscepitibitity test by K-B disk diffusion test.The initial typing was conducted by PCR amplification using TEM、SHV and CTX-M universal primers as well as sequence analysis on PCR products.

  Results   Most of the ESBLs were resistant to cefotoxime and sensitive to ceftazidime.Least of them were resistant to both drugs.Within these strains, the former were mostly CTX-M-3 as well as CTX-M-12、CTX-M-14 type by PCR using CTX-M primers, the later were mostly SHV-12 as well as SHV-40、SHV-33 and SHV-5 type using SHVprimers.All of the strains were TEM-1 broad-spectrum β-lactamases using TEM primers.

  Conclusion   The majority of ESBLs were CTX-M-3 genotype in gram-negative bacilli. There were 2-3 kinds of lactamases in 62.9% bacilli.