Prevalence of type III secretion genes in clinical and environmental isolates of Pseudomonas aeruginosa
Prevalence of type III secretion genes in clinical and environmental isolates of Pseudomonas aeruginosa
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DOI：
10.1099/00221287-147-10-2659
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发表时间：
2001-10-01
期刊：
影响因子：
2.8
通讯作者：
Hauser, AR
中科院分区：
文献类型：
--
作者：
Feltman, H;Schulert, G;Hauser, AR
铜绿假单胞菌的III型分泌系统转运四种已知的效应蛋白：ExoS， ExoT， ExoU和ExoY。然而，III型分泌系统基因或效应编码基因在临床和环境分离株铜绿假单胞菌中的流行程度尚未得到很好的研究。对100多株铜绿假单胞菌进行了Southern杂交和PCR分析，以确定这些基因的分布。临床分离株来自尿液、气管内、血液和伤口标本、囊性纤维化（CF）患者的痰以及非医院环境部位。popB基因被用作标记存在编码III型分泌机制蛋白的大染色体位点。每个分离株都含有popB基因，这表明在所有分离株中至少存在这种大染色体位点的一部分。同样，每个分离物都含有外逸物样序列。而exoS、exoU和exoY基因为可变性状。总体而言，检测的分离株中72%含有exoS基因，28%含有exoU基因，89%含有exoY基因。有趣的是，在exoS和exoU基因的存在之间发现了负相关，因为除了两个分离株外，所有分离株都含有exoS或exoU，而不是两者都含有。临床分离株和环境分离株之间，以及不同疾病部位培养的分离株之间，除CF呼吸道分离株外，exoS、exoU或exoY患病率均无显著差异。与来自其他感染部位（包括非CF患者的呼吸道）的分离株相比，CF分离株携带exoU基因的频率较低，而携带exoS基因的频率较高。这些结果表明，铜绿假单胞菌III型分泌系统几乎存在于所有临床和环境分离株中，但来自不同疾病部位的分离株和分离株群体的效应基因型不同。III型分泌基因在临床分离株中的普遍存在与该系统在人类疾病中的重要作用是一致的。
The type III secretion system of Pseudomonas aeruginosa transports four known effector proteins: ExoS, ExoT, ExoU and ExoY. However, the prevalence of the type III secretion system genes or the effector-encoding genes in clinical and environmental isolates of P. aeruginosa has not been well studied. Southern hybridization analyses and PCR were performed on over 100 P. aeruginosa isolates to determine the distribution of these genes. Clinical isolates were obtained from urine, endotracheal, blood and wound specimens, from the sputum of cystic fibrosis (CF) patients, and from non-hospital environmental sites. The popB gene was used as a marker for the presence of the large chromosomal locus encoding the type III secretion machinery proteins. Each isolate contained the popB gene, indicating that at least a portion of this large chromosomal locus was present in all isolates. Likewise, each isolate contained exoT-like sequences. In contrast, the exoS, exoU and exoY genes were variable traits. Overall, 72% of examined isolates contained the exoS gene, 28% contained the exoU gene, and 89% contained the exoY gene. Interestingly, an inverse correlation was noted between the presence of the exoS and exoU genes in that all isolates except two contained either exoS or exoU but not both. No significant difference in exoS, exoU or exoY prevalence was observed between clinical and environmental isolates or between isolates cultured from different disease sites except for CF respiratory isolates. CF isolates harboured the exoU gene less frequently and the exoS gene more frequently than did isolates from some of the other sites of infection, including the respiratory tract of patients without CF. These results suggest that the P. aeruginosa type III secretion system is present in nearly all clinical and environmental isolates but that individual isolates and populations of isolates from distinct disease sites differ in their effector genotypes. The ubiquity of type III secretion genes in clinical isolates is consistent with an important role for this system in human disease.