University of Washington, Seattle, Washington, USA.
Appl Environ Microbiol. 2013 Sep;79(18):5601-7. doi: 10.1128/AEM.01443-13. Epub 2013 Jul 12.
Our understanding of the sources of Mycobacterium avium infection is partially based on genotypic matching of pathogen isolates from cases and environmental sources. These approaches assume that genotypic identity is rare in isolates from unlinked cases or sources. To test this assumption, a high-resolution PCR-based genotyping approach, large-sequence polymorphism (LSP)-mycobacterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR), was selected and used to analyze clinical and environmental isolates of M. avium from geographically diverse sources. Among 127 clinical isolates from seven locations in North America, South America, and Europe, 42 genotypes were observed. Among 12 of these genotypes, matches were seen in isolates from apparently unlinked patients in two or more geographic locations. Six of the 12 were also observed in environmental isolates. A subset of these isolates was further analyzed by alternative strain genotyping methods, pulsed-field gel electrophoresis and MIRU-VNTR, which confirmed the existence of geographically dispersed strain genotypes. These results suggest that caution should be exercised in interpreting high-resolution genotypic matches as evidence for an acquisition event.
我们对鸟分枝杆菌感染源的了解部分基于从病例和环境源分离的病原体分离株的基因型匹配。这些方法假设来自无关联病例或来源的分离株的基因型同一性很少见。为了检验这一假设，选择了一种基于高分辨率 PCR 的基因分型方法，即长序列多态性（LSP）-分枝杆菌插入重复单位-可变数量串联重复（MIRU-VNTR），并用于分析来自地理上不同来源的鸟分枝杆菌临床和环境分离株。在来自北美、南美和欧洲七个地点的 127 株临床分离株中，观察到 42 种基因型。在其中 12 种基因型中，在两个或更多地理位置的显然无关联患者的分离株中观察到匹配。其中 6 种也在环境分离株中观察到。这些分离株的一部分进一步通过替代菌株基因分型方法进行了分析，即脉冲场凝胶电泳和 MIRU-VNTR，这证实了存在地理上分散的菌株基因型。这些结果表明，在将高分辨率基因型匹配解释为获得事件的证据时应谨慎行事。
