水产养殖环境耐药细菌中复合1型整合子的流行特征

Prevalent feature of complex class 1 integrons in drug-resistant bacteria isolated from aquaculture environment

摘要:

【目的】了解复合1型整合子在水产养殖环境中的分布和流行特征。【方法】对108株分离自福建水产养殖场的耐药细菌，通过PCR和序列分析，检测其复合1型整合子上下游保守区和可变区的携带情况。【结果】有86株(79.6%)和47株(43.5%)分别携带1型整合子和ISCR1元件，这两种上下游保守区均携带的耐药细菌则有26株(24.1%)，其中16株(14.8%)耐药细菌成功地扩增出上下游可变区，分布于8属9种。进一步对ISCR1上下游序列的拼接和分析，表明这16株细菌携带两种类型的复合1型整合子：(1) intI1-aac(6')-Ib-cr-arr-3-dfrA27-aadA16- qacE△1-sul1-ISCR1-sdr-qnrB6-qacE△1-sul1 (15株)；(2) intI1-aac(6')-Ib-cr-arr-3-dfrA27-aadA16- qacE△1-sul1-ISCR1-sapA-like-qnrB2-qacE△1(truncated)-sul1 (1株，肺炎克雷伯菌C12)，该阵列为新发现的复合1型整合子结构。【结论】复合1型整合子在水产养殖环境中并不少见，且存在于多种细菌中，但其基因阵列结构缺乏多样性。

Abstract:

[Objective] In order to understand the distribution and genomic characteristics of complex class 1 integron in aquaculture environment. [Methods] 108 strains of drug-resitstiant bacteria were isolated from aquaculture farms in Fujian province to check the carrying status of the upstream and downstream conserved and variable regions of the complex class 1 integron by PCR and sequencing. [Results] The results showed that 86 strains (79.6%) carried class 1 integrons and 47 strains (43.5%) carried ISCR1 elements. However, only 26 strains (24.1%) have both of the elements, of which 16 strains (14.8%) were successfully amplified upstream and downstream variable regions, involving 9 species, 8 genera. Furthermore, splicing and analysis of upstream and downstream sequences indicated that these 16 strains carried two types of complex class 1 integrons: (1) intI1-aac(6′)-Ib-cr-arr-3-dfrA27-aadA16-qacE△1-sul1-ISCR1-sdr-qnrB6-qacE△1-sul1(15 strains); intI1-aac(6′)-Ib-cr-arr-3-dfrA27-aadA16-qacE△1-sul1-ISCR1-sapA-like-qnrB2-qacE△1(truncated)-sul1 (only Klebsiella pneumoniae C12 strain), which is a noval structure of complex class 1 integron. [Conclusion] The complex class 1 integron is not infrequent in aquaculture environment and exists in various bacteria, yet its gene structure lacks diversity.