Departments of Clinical Sciences and Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden. National Veterinary Institute, Department of Bacteriology, Uppsala, Sweden.
Environ Microbiol Rep. 2010 Dec;2(6):720-7. doi: 10.1111/j.1758-2229.2010.00165.x.
The occurrence of intestinal spirochaetes of genus Brachyspira in wild rodents was studied by cultivating 209 caecal samples. Spirochaetal cultures were obtained from 83% of rats and 33% of house mice. Biochemical characterization and six different species-specific PCR methods were applied to 101 of 118 isolates and a selection of 34 brachyspiras were further studied by sequencing of the 16S rRNA gene. The results showed that isolates representing all the established biochemical phenotypes could be cultured from the rodents, including the porcine pathogens Brachyspira hyodysenteriae and Brachyspira pilosicoli. Phylogenetic studies indicated that rodents carry Brachyspira spp. that are closely related to porcine and avian isolates, as well as variants previously not described. One group of hippurate-negative rat isolates were shown to possess the 16S rRNA gene hexa(T) nucleotide segment, previously described only in B. pilosicoli and 'Brachyspira corvi', and phylogenetically they formed a sister lineage of the B. pilosicoli cluster. Furthermore, a large number of the rodents were colonized by slowly growing, non- or weakly haemolytic spirochaetes. Most of these brachyspiras were isolated at 37°C and phylogenetically they formed two separate clusters. Sequence analysis of their 16S rRNA genes indicated that the new variants of Brachyspira spp. may constitute novel species of the genus Brachyspira.
本研究通过培养 209 个盲肠样本，对野生啮齿动物肠道螺旋体属 Brachyspira 的发生情况进行了研究。从大鼠和小家鼠中分别获得了 83%和 33%的螺旋体培养物。对 118 个分离株中的 101 个进行了生化特征和 6 种不同种特异性 PCR 方法的应用，并对 34 个选择的短螺旋体进一步进行了 16S rRNA 基因测序研究。结果表明，从啮齿动物中可以培养出代表所有已建立生化表型的分离株，包括猪病原体猪痢疾密螺旋体和猪短螺旋体。系统发育研究表明，啮齿动物携带的 Brachyspira 属与猪和禽分离株密切相关，还有以前未描述的变异株。一组鼠类的尿囊酸盐阴性分离株被证明具有 16S rRNA 基因六（T）核苷酸片段，该片段以前仅在猪短螺旋体和“Brachyspira corvi”中描述，在系统发育上，它们与猪短螺旋体群形成姊妹谱系。此外，大量啮齿动物被缓慢生长、非或弱溶血螺旋体定植。这些短螺旋体中的大多数在 37°C 下分离，在系统发育上形成两个独立的聚类。它们的 16S rRNA 基因序列分析表明，这些短螺旋体的新变种可能构成短螺旋体属的新种。
