Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
Department of Medicine Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
Environ Microbiol Rep. 2018 Aug;10(4):485-492. doi: 10.1111/1758-2229.12653.
Pseudomonas aeruginosa uses its type III secretion system to inject the effector proteins ExoS and ExoU into eukaryotic cells, which subverts these cells to the bacterium's advantage and contributes to severe infections. We studied the environmental reservoirs of exoS+ and exoU+ strains of P. aeruginosa by collecting water, soil, moist substrates and plant samples from environments in the Chicago region and neighbouring states. Whole-genome sequencing was used to determine the phylogeny and type III secretion system genotypes of 120 environmental isolates. No correlation existed between geographic separation of isolates and their genetic relatedness, which confirmed previous findings of both high genetic diversity within a single site and the widespread distribution of P. aeruginosa clonal complexes. After excluding clonal isolates cultured from the same samples, 74 exoS+ isolates and 16 exoU+ isolates remained. Of the exoS+ isolates, 41 (55%) were from natural environmental sites and 33 (45%) were from man-made sites. Of the exoU+ isolates, only 3 (19%) were from natural environmental sites and 13 (81%) were from man-made sites (p < 0.05). These findings suggest that man-made water systems may be a reservoir from which patients acquire exoU+ P. aeruginosa strains.
铜绿假单胞菌利用其三型分泌系统将效应蛋白 ExoS 和 ExoU 注入真核细胞，使这些细胞为细菌所用，并导致严重感染。我们通过从芝加哥地区及周边州的环境中收集水、土壤、潮湿基质和植物样本，研究了铜绿假单胞菌 exoS+和 exoU+菌株的环境库。全基因组测序用于确定 120 个环境分离株的系统发育和三型分泌系统基因型。分离株的地理分离与遗传相关性之间没有相关性，这证实了先前的发现，即在单个地点存在高度遗传多样性和铜绿假单胞菌克隆复合体的广泛分布。在排除从同一样本培养的克隆分离株后，仍有 74 个 exoS+分离株和 16 个 exoU+分离株。在 exoS+分离株中，41 个（55%）来自自然环境地点，33 个（45%）来自人为地点。在 exoU+分离株中，只有 3 个（19%）来自自然环境地点，13 个（81%）来自人为地点（p<0.05）。这些发现表明，人为水系统可能是患者获得 exoU+铜绿假单胞菌菌株的来源。
