High Prevalence of Diarrheagenic Escherichia coli among Children with Diarrhea in Kenya
High Prevalence of Diarrheagenic Escherichia coli among Children with Diarrhea in Kenya
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DOI：
10.7883/yoken.jjid.2016.064
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发表时间：
2017-01-01
影响因子：
2.2
通讯作者：
Yamasaki, Shinji
中科院分区：
文献类型：
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作者：
Iijimal, Yoshio;Oundo, Joseph O.;Yamasaki, Shinji
产血性大肠埃希菌(DEC)是世界范围内，尤其是发展中国家地方性和流行性腹泻的重要病原体。虽然有一些例外，但在选择性培养上不能将DEC与共生大肠杆菌区分开来。大多数研究采用集落分离方法，不能检测到低数量的DEC，因此，这些研究可能低估了DEC的发病率。在本研究中，我们采用了一种针对5类DEC毒力基因的菌落扫描方法，该技术可以从数百种共生大肠杆菌中检测出非常少量的DEC。在肯尼亚306名腹泻儿童中，171人(55.9%)检出DEC。肯尼亚的DEC患病率明显高于印度尼西亚(30/143，21.0%)。肯尼亚DEC多重感染的发生率较高(69/306，23.2%)，提示DEC的感染源可能与严重污染的食物和水有关。相比之下，肯尼亚150名健康成年人中只有9人(6.0%)携带DEC。考虑到健康的成年人天生就有非DEC，有趣的是，孩子们在成长过程中如何排斥DEC而不是非DEC。DEC的排斥可能涉及多种机制，如粘膜免疫和肠道微生物区系。
Diarrheagenic Escherichia coli (DEC) is an important agent of endemic and epidemic diarrhea worldwide, particularly in developing countries. DEC cannot be differentiated from commensal E. coli on selective media, although there are a few exceptions. Most studies use the colony isolation method, which cannot detect low numbers of DEC, and therefore, these studies might underestimate the incidence of DEC. In the present study, we employed a colony sweep method with real-time PCR targeting virulence genes of 5 categories of DEC; this technique can detect very low numbers of DEC among hundreds of commensal E. coli. DEC was detected in 171 (55.9%) of 306 children with diarrhea in Kenya. The prevalence of DEC in Kenya was notably higher than that (30 in 143, 21.0%) in Indonesia. Occurrences of multiple DEC infection in Kenya were frequent (69 in 306, 23.2%), suggesting that the source of DEC infection may be related to grossly contaminated food and water. In contrast, only 9 (6.0%) of 150 healthy adults in Kenya carried DEC. Considering that healthy adults naturally harbor non-DEC, it is interesting how children exclude DEC but not non-DEC as they grow up. Several mechanisms, such as mucosal immunity and intestinal microbiota, might be involved in the exclusion of DEC.