志贺菌中成簇规律间隔短回文重复序列的分子分布特征

目的 探索志贺菌中成簇规律间隔短回文重复序列(CRISPR)的分布。方法 共选择志贺菌分离株52株, 其中河南41株, 江西6株, 北京5株。利用PCR扩增志贺菌的4个CRISPR位点(S1、S2、S3、S4), 产物送测序, 分析CRISPR的重复序列和间隔序列。结果 志贺菌的4个CRISPR位点阳性率分别为33. 69%(S1)、50.00%(S2)、82.69%(S3)和73.08%(S4);S1和S3包括2种亚型, S2有3种亚型, S4包括4种亚型。2004年前分离的河南分离株中检出S1位点, 2004年后分离的菌株中均未检出该位点;S2、S3和S4在两组的分布没有差异。结论 志贺菌各CRISPR位点含有不同亚型, 河南分离株S1的分布与细菌分离时间有关, 而S2、S3 及S4和分离时间无关。

Molecular characteristics of Clustered Regularly Interspaced Short Palindromic Repeat in Shigella

Objective To detect the molecular characteristics of Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) in Shigella and to analyze the distribution of CRISPR related to the time of isolation. Methods Of the 52 Shigella strains, 41 were isolated from Henan, 6 from Jiangxi and 5 isolated from Beijing. Both CRISPR locus of S1, S2, S3 and S4 in Shigella were detected by polymerase chain reaction (PCR). The PCR products were sequenced and compared. Results The positive rates of CRISPR locus in Shigella were 33.69%(S1), 50.00%(S2), 82.69%(S3) and 73.08%(S4), respectively. Two subtypes were discovered in S1 and S3 locus. Three subtypes were discovered in S2 locus. Four different subtypes were discovered in S4 locus. The isolates from Henan strains were divided into two groups by the time of isolation. Distributions of S1 were different, before or after 2004, on Shigella. S1 could not be detected after 2004. There were no statistical differences of S2, S3 and S4 in two groups. Conclusion Different CRISPR subtypes or Shigella were discovered. A significant correlation was noticed between the CRISPR S1 related to the time of isolation but not between S2, S3 or S4 on the time of isolation.