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11.
《Veterinary microbiology》2015,175(1):150-156
Sheep constitute an important source of zoonotic pathogens as Shiga toxin-producing Escherichia coli (STEC). In this study, the prevalence, serotypes and virulence profiles of STEC were investigated among 130 healthy sheep from small and medium farms in southern Brazil. STEC was isolated from 65 (50%) of the tested animals and detected in all flocks. A total of 70 STEC isolates were characterized, and belonged to 23 different O:H serotypes, many of which associated with human disease, including hemolytic-uremic syndrome (HUS). Among the serotypes identified, O76:H19 and O65:H– were the most common, and O75:H14 and O169:H7 have not been previously reported in STEC strains. Most of the STEC isolates harbored only stx1, whereas the Stx2b subtype was the most common among those carrying stx2. Enterohemolysin (ehxA) and intimin (eae) genes were detected in 61 (87.1%) and four (5.7%) isolates, respectively. Genes encoding putative adhesins (saa, iha, lpfO113) and toxins (subAB and cdtV) were also observed. The majority of the isolates displayed virulence features related to pathogenesis of STEC, such as adherence to epithelial cells, high cytotoxicity and enterohemolytic activity. Ovine STEC isolates belonged mostly to phylogenetic group B1. PFGE revealed particular clones distributed in some farms, as well as variations in the degree of genetic similarity within serotypes examined. In conclusion, STEC are widely distributed in southern Brazilian sheep, and belonged mainly to serotypes that are not commonly reported in other regions, such as O76:H19 and O65:H–. A geographical variation in the distribution of STEC serotypes seems to occur in sheep. 相似文献
12.
[目的]比较副猪嗜血杆菌国内流行血清型菌株感染后小鼠外周血淋巴细胞、血清细胞因子及免疫球蛋白水平的变化情况。[方法]将72只小鼠分为4组,分别腹腔注射副猪嗜血杆菌血清型4、5和12菌株,检测3 d、7 d和15 d各组外周血T、B淋巴细胞及血清细胞因子和Ig水平。[结果]副猪嗜血杆菌感染小鼠3 d,T、B淋巴细胞数量明显高于对照组,而随着感染时间的延长而逐渐下降。Ig G、IFN-γ和IL-10水平随感染时间的延长而逐渐增高,而Ig A、Ig M和Ig E水平逐渐降低。感染3 d,Th1/Th2比值稍有下降,而Th1/Th2比值随着感染时间的延长而逐渐升高,明显高于对照组。不同血清型感染在各时间点之间T、B淋巴细胞、Ig A、Ig M、Ig E、IFN-γ、IL-10和Th1/Th2差异均无统计学意义,而血清型4和5感染组小鼠血清Ig G均明显高于血清型12组。[结论]除Ig G以外,副猪嗜血杆菌国内流行血清型4、5和12菌株感染小鼠后外周血淋巴细胞、血清细胞因子及Ig水平无明显差异。 相似文献