無症候性Entamoeba histolytica感染症の臨床的特徴と腸内マイクロバイオーム

Clinical features and gut microbiome of asymptomatic Entamoeba histolytica infection.

• Yasuaki Yanagawa
• Naoyoshi Nagata
• Kenji Yagita
• Kazuhiro Watanabe
• Hidetaka Okubo
• Yoshimi Kikuchi
• Hiroyuki Gatanaga
• Shinichi Oka
• Koji Watanabe

抄録

背景:

エンタメバ組織炎菌感染症は一部の先進国では性感染症の一つである。無症候性感染はしばしば発生し、感染源となりうるが、E. histolyticaの発症機序に関するデータは限られている。

BACKGROUND: Entamoeba histolytica infection is a sexually transmitted disease in some developed countries. Asymptomatic infection often occurs and can be a source of transmission; however, limited data are available regarding the pathogenesis of E. histolytica.

方法:

単施設横断的研究である。臨床的に疑われる症例からプロスペクティブに検体を採取した。"E. histolytica感染症」とは、臨床検体のPCRによりE. histolyticaの同定が確認された症例と定義した。また，無症候性症例と症候性浸潤症例のデータを比較した．

METHODS: This is a single center cross-sectional study. Specimens were prospectively collected from patients with clinically suspected cases. "E. histolytica infection" was defined as a case in which the identification of E. histolytica was confirmed by PCR of a clinical specimen. Data from asymptomatic cases were compared with those from symptomatic invasive cases.

結果:

研究期間中にE. histolyticaに感染した64例（うち無症候性の13例）が確認された。微生物学的診断は、これらの症例の26.6％（17/64例）で内視鏡サンプリングにより行われた。内視鏡検査では全例で巨視的に病変が確認されたが，生検検体の病理組織検査の感度はPCR法（94.7％）に比べて低感度（45.5％）であった．無症状の症例では，感染部位は大腸近位部に限られており，さらに，感染部位ではトロポゾアイトが頻繁に確認されたが，便中には嚢胞型が一般的に検出された．腸内マイクロバイオーム解析の結果、無症候性症例の方が浸潤性症例よりも均一な組成を示し、その内訳は、ルミノコッカス科、コリオバクテリア科、クロストリジアセア科が比較的多く、ストレプトコッカス科が少ないことが明らかになった。

RESULTS: Sixty-four E. histolytica-infected cases, including 13 asymptomatic cases, were identified during the study period. Microbiological diagnosis was made by endoscopic sampling in 26.6% of these cases (17/64). Endoscopy identified macroscopically visible lesions in all cases; however, the sensitivity of histopathology on biopsy samples was low (45.5%) compared with PCR (94.7%). In asymptomatic cases, infection sites were limited around the proximal colon; moreover, trophozoites were frequently identified at infection sites whereas cystic forms were commonly detected in stools. Gut microbiome analyses showed more uniform composition in asymptomatic cases than in symptomatic invasive cases, which were represented by a relatively high abundance of Ruminococcaceae, Coriobacteriaceae, and Clostridiaceae, and a low abundance of Streptococcaceae.

結論:

これらの結果から、E. histolyticaのシストや減衰は、腸内マイクロバイオームを含む腸内環境に大きく影響されていることが示唆された。

CONCLUSION: These results indicate that the encystation and attenuation of E. histolytica are highly affected by the intestinal contents, including the gut microbiome.

© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America.