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目的了解我国部分地区非O157产志贺毒素大肠杆菌分离株的志贺毒素基因变种及其黏附相关基因,为进一步研究致病机制提供依据。方法采用聚合酶链反应(polymerase chain reaction,PCR)方法对29株分离菌株的stx1、stx2基因全长扩增并测序,通过与GenBank中已公布的变种序列比对确定菌株stx1、stx2基因的变种类型。对位于LEE毒力岛上的eaeA、escF、escC、tir、espA、espB、espD基因及LEE以外其他黏附相关基因iha、toxB、efa1、sfpA、lpfAO157/OI-141、lpfAO157/OI-154、saa、lpfAO113、eibG进行PCR检测。结果 25株stx1阳性菌株中有13株携带stx1a原毒素,12株携带stx1c变种;10株stx2阳性菌株中,7株携带stx2d变种,1株为stx2a原毒素,1株携带stx2g变种,1株携带与stx2eA亚单位、stx2dB亚单位最接近的stx2变种。LEE岛上的7个基因检测结果均为阴性,黏附相关基因iha阳性率为89.7%(26/29),saa阳性菌株3株、eibG阳性菌株1株,其余6个黏附相关基因均为阴性。结论我国部分非O157 STEC菌株的志贺毒素基因以stx1c、stx2d变种为主,LEE毒力岛不存在,而黏附相关基因iha广泛存在于不同血清型的产志贺毒素大肠杆菌菌株中。
Objective To understand the gene and its related genes of Shiga toxin gene isolated from non-O157 Shiga Toxigenic Escherichia coli isolates in parts of China, and provide the basis for further study of pathogenic mechanism. Methods The full-length stx1 and stx2 genes of 29 isolates were amplified by polymerase chain reaction (PCR) and sequenced. Variants of stx1 and stx2 genes were identified by comparison with published sequences in GenBank Types of. The expression levels of eaeA, escF, escC, tir, espA, espB, espD genes and other adhesion-related genes other than LEE in the virulence island of LEE iha, toxB, efa1, sfpA, lpfAO157 / OI- 141, lpfAO157 / OI- 154, saa , LpfAO113, eibG for PCR detection. Results Of the 25 stx1 positive strains, 13 were stx1a protoxins and 12 were stx1c strains. Of the 10 stx2 positive isolates, 7 strains carried stx2d strain, 1 stx2a protoxin, 1 strain stx2g and 1 strain The stx2 variant closest to the stx2eA subunit, the stx2dB subunit. The results of 7 genes in LEE island were negative. The positive rate of adhesion related gene iha was 89.7% (26/29), 3 strains were positive for saa and 1 for eibG. The other 6 genes were negative for adhesion. Conclusion StX1c and stx2d variants are the major shiga toxin genes in some non-O157 STEC strains in China. LEE virulence island is absent. However, the ih adhesion-related genes are widely found in Shiga toxin-producing Escherichia coli strains of different serotypes.