Tufts Cummings School of Veterinary Medicine, North Grafton, MA, USA.
Microb Ecol. 2010 Feb;59(2):277-83. doi: 10.1007/s00248-009-9568-y. Epub 2009 Aug 12.
We determined whether Francisella spp. are present in water, sediment, and soil from an active tularemia natural focus on Martha's Vineyard, Massachusetts, during a multiyear outbreak of pneumonic tularemia. Environmental samples were tested by polymerase chain reaction (PCR) targeting Francisella species 16S rRNA gene and succinate dehydrogenase A (sdhA) sequences; evidence of the agent of tularemia was sought by amplification of Francisella tularensis-specific sequences for the insertion element ISFTu2, 17-kDa protein gene tul4, and the 43-kDa outer membrane protein gene fopA. Evidence of F. tularensis subsp. tularensis, the causative agent of the human infections in this outbreak, was not detected from environmental samples despite its active transmission among ticks and animals in the sampling site. Francisella philomiragia was frequently detected from a brackish-water pond using Francisella species PCR targets, and subsequently F. philomiragia was isolated from an individual brackish-water sample. Distinct Francisella sp. sequences that are closely related to F. tularensis and Francisella novicida were detected from samples collected from the brackish-water pond. We conclude that diverse Francisella spp. are present in the environment where human cases of pneumonic tularemia occur.
我们在马萨诸塞州玛莎葡萄园岛的一个活跃的土拉热自然疫源地，在多年的肺鼠疫爆发期间，确定了弗氏菌是否存在于水、沉积物和土壤中。通过聚合酶链反应 (PCR) 针对弗朗西斯菌属 16S rRNA 基因和琥珀酸脱氢酶 A (sdhA) 序列测试环境样本；通过扩增土拉热弗朗西斯菌特异性序列来寻找土拉热弗朗西斯菌的证据，这些序列包括插入元件 ISFTu2、17 kDa 蛋白基因 tul4 和 43 kDa 外膜蛋白基因 fopA。尽管在采样点的蜱虫和动物中存在这种疾病的活跃传播，但在环境样本中并未检测到此次暴发中人类感染的病原体——弗氏菌亚种土拉热弗朗西斯菌的证据。使用弗朗西斯菌属 PCR 靶标经常从一个咸水池塘中检测到弗氏菌属 philomiragia，随后从一个咸水样本中分离到弗氏菌属 philomiragia。从咸水池塘采集的样本中检测到与土拉热弗朗西斯菌和弗朗西斯菌 novicida 密切相关的独特弗朗西斯菌属序列。我们得出结论，在发生人类肺鼠疫的环境中存在多种弗氏菌属。
