不同年代铜绿假单胞菌1型整合子结构比较

Comparison of class 1 integrons detected in Pseudomonas aeruginosa in different periods

目的研究1992—1996年和2003—2005年两个时间段90份铜绿假单胞菌1型整合子结构,比较其结构差异,以了解不同年代1型整合子变化趋势。方法用常规和长片段 PCR 方法扩增1型整合子及耐药基因,并对 PCR 产物进行测序和 GenBank 比对分析。结果 41份1992—1996年间样本有13份检出1型整合子结构,长片段 PCR 扩增1型整合子 DNA 平均长度为1 868 bp,平均包含2个耐药基因,包括qacEΔ1(n=6)、sul1(n=14)、aadA1(n=2)、aadB(n=1)、PSE-1(n=2)和 tetA(n=1)等6种耐药基因,形成5种耐药基因盒组合。49份2003—2005年间样本中有19份检出1型整合子结构,长片段 PCR 扩增产物平均长度为3 383 bp,平均包含3.6个耐药基因,包括qacEΔ1(n=18)、sul1(n=25)、aadA1(n=6)、aadB(n=7)、aacA4(n=2)、PSE-1(n=3)、VEB-1(n=4)、OXA10(n=1)、cm1A(n=1)和 tetA(n=2)10种耐药基因,形成9种耐药基因盒组合。结论根据整合子碱基数量和所携带耐药基因盒数量,发现2003—2005年间检出的1型整合子结构比1992—1996间检出的复杂程度增加。

Objective To study the structure of class 1 integrons in 90 strains of Pseudomonas aeruginosa isolated during two periods of 1992-1996 and 2003-2005, and to get information about the structure changing of class 1 integrons by comparing their structures in two different periods. Methods Routine PCR and long PCR were performed to amplify the class 1 integrons and the gene cassettes they carried, followed with sequencing and blast via GenBank. Results Thirteen out of 41 strians ioslated during the period of 1992-1996 were positive on class 1 intergrons. Long PCR showed that the class 1 integron was 1868 bp in length and contained 2 resistance genes averagely. Six types of resistance genes of qacE△1 （ n = 6） , sul1 （ n = 14）, aadA1 （ n = 2）, aadB （ n = 1 ）, PSE-1 （ n = 2） and tetA （ n = 1 ） were found in these integrons, which consisted of 5 patterns of resistance cassette arrangements. Nineteen strains were proved to carry class 1 integrons in 49 isolates from 2003-2005. The mean DNA sequence length of them was 3383 bp with 3.6 resistant genes in averagely, 10 types of resistance genes, qacE△1 （ n = 18）, sull （ n = 25 ）, aadA1 （ n = 6）, aadS（n=7）, aacA4（n=2）, PSE-I（n=3）, VEB-1（n=4）, OXA10（n=1）, cm1A（n=1） and tetA（n = 2 ）, were identified in these integrons, which were composed of 9 patterns of resistance cassette arrangements. Conclusion In terms of produce length and resistance cassettes carried in the integrons, greater complexity is found in the structure of class 1 integrons in strains isolated during 2003-2005 than those during 1992-1996.