粘质沙雷菌中SHV型β-内酰胺酶编码基因的克隆及序列分析

Cloning and sequencing of the gene encoding SHV subtype of extended spectrum β-lactamases from Serratia marcescens

目的研究重庆地区临床分离的粘质沙雷菌E 121编码超广谱β-内酰胺酶(ESBL s)的基因。方法PCR扩增ESBL s编码基因片段,克隆入pUCm-T载体,双脱氧链终止法测定核苷酸序列并确定亚型,等电聚焦测定β-内酰胺酶的等电点(pI)。结果PCR扩增结果显示粘质沙雷菌E 121产生的ESBL s为SHV型,其基因片段含756个核苷酸,G enB ank查询其核苷酸序列与SHV-28型ESBL s完全相同。该耐药株至少含有等电点pI约为5.4和8.2的两种β-内酰胺酶。结论重庆地区粘质沙雷菌E 121所产ESBL s亚型为SHV-28。

Objective To determine the gene encoding the β--lactamases in Serratia marcescens E121 isolated from Chongqing area. Methods The genes encoding β-lactamases produced by E121 strain were amplified by PCR. The purified PCR products were cloned into pUCm-T vector and sequenced by Sanger＇s dideoxy chain termination composition method. The isoelectric points （pI） of β-lactamases were analyzed by isoelectric focus systems. Results The genes encoding β-lactamases were identified as SHV by PCR. Their PCR products had 756 nucleotides, which had the same sequence as the SHV-28-encoding gene sequence in GenBank. The pI of the β-lactamases in Serratia marcescens E121 were 5.4 and 8.2. Conclusion The β-lactamases produced by Serratia marcescens E121 isolated from Chongqing area were identified as SHV-28 which had been previously reported.