Rapid host switching in generalist Campylobacter strains erodes the signal for tracing human infections.
Rapid host switching in generalist Campylobacter strains erodes the signal for tracing human infections.
复制标题
通才弯曲杆菌菌株中快速的宿主切换侵蚀了追踪人类感染的信号。
DOI：
10.1038/ismej.2015.149
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发表时间：
2016-03
期刊：
影响因子：
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通讯作者：
Sheppard SK
中科院分区：
文献类型：
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作者：
Dearlove BL;Cody AJ;Pascoe B;Méric G;Wilson DJ;Sheppard SK
空肠弯曲杆菌和结肠弯曲杆菌是发达国家细菌性胃肠炎的最大病因，人类感染通常由与受感染肉类相关的人畜共患病传播引起。因为弯曲杆菌被认为不能在肠道外很好地存活，所以宿主相关的种群在遗传上被不同程度地隔离。因此，大多数菌株的可能来源可以通过基因组中与宿主相关的变异来确定。这对于确定人类感染源的特征具有指导意义。然而，一些常见的菌株，特别是属于ST-21，ST-45和ST-828克隆复合体的分离株，似乎具有广泛的宿主范围，阻碍了来源归属。在这里，全基因组测序有可能揭示与宿主特异性相关的精细遗传结构。我们发现，这些克隆复合体中动物宿主物种之间的人畜共患病传播率是如此之高，以至于宿主关联的信号几乎被消除，估计ST-21，ST-45和ST-828复合体中每1.6，1.8和12年分别发生一次人畜共患病传播事件。我们将89%的临床病例归因于鸡源，10%归因于牛，1%归因于猪。我们的研究结果表明，常见的C。jejuni和C.感染人类的大肠杆菌适应了一种多面手的生活方式，允许在不同宿主之间快速传播。此外，他们表明，这些复合物中宿主相关性的弱信号对精确定位临床感染的来源提出了挑战，强调了全基因组测序虽然强大，但不能取代对疑似传播水库的密集采样。
Campylobacter jejuni and Campylobacter coli are the biggest causes of bacterial gastroenteritis in the developed world, with human infections typically arising from zoonotic transmission associated with infected meat. Because Campylobacter is not thought to survive well outside the gut, host-associated populations are genetically isolated to varying degrees. Therefore, the likely origin of most strains can be determined by host-associated variation in the genome. This is instructive for characterizing the source of human infection. However, some common strains, notably isolates belonging to the ST-21, ST-45 and ST-828 clonal complexes, appear to have broad host ranges, hindering source attribution. Here whole-genome sequencing has the potential to reveal fine-scale genetic structure associated with host specificity. We found that rates of zoonotic transmission among animal host species in these clonal complexes were so high that the signal of host association is all but obliterated, estimating one zoonotic transmission event every 1.6, 1.8 and 12 years in the ST-21, ST-45 and ST828 complexes, respectively. We attributed 89% of clinical cases to a chicken source, 10% to cattle and 1% to pig. Our results reveal that common strains of C. jejuni and C. coli infectious to humans are adapted to a generalist lifestyle, permitting rapid transmission between different hosts. Furthermore, they show that the weak signal of host association within these complexes presents a challenge for pinpointing the source of clinical infections, underlining the view that whole-genome sequencing, powerful though it is, cannot substitute for intensive sampling of suspected transmission reservoirs.