感染性大腸炎の最近の動向と診断の要点

Recent Trends in Infectious Colitis and Key Points in Diagnosis

要旨●感染性大腸炎は主に組織侵入性とサイトトキシン産生性の病原体が原因となる．食水系感染が最も多いが，ヒトや保因動物，環境を媒介とした感染もみられる．一部の疾患の発生傾向は食中毒統計や感染症発生動向調査の報告などで知ることができる．頻度的にはカンピロバクター腸炎が多いが，重大性では腸管出血性大腸菌感染症が筆頭に挙がる．Clostridioides difficile感染症は従来医療現場の感染症と考えられていたが，近年は市中感染が注目されている．感染性大腸炎の確定診断には病原体の直接または間接的証明が必要であるが，新しい検査法を活用しつつも効率よく診断を行うことが重要である．内視鏡をはじめとする画像診断は有用であるが，炎症性腸疾患（IBD）と誤診するリスクをはらんでいる．

　Infectious colitis is mainly caused by invasive or cytotoxin-producing pathogens. Food- and water-borne infections are the most common ; however, infections mediated by humans, animal vectors, or the environment also exist. Trends in disease occurrence can be understood from reports such as food poisoning statistics and infectious disease trend surveys. Although Campylobacter enteritis occurs more frequently, enterohemorrhagic Eshcerichia coli infection is one of the most severe forms of infection. Clostridioides difficile infection has long been considered a nosocomial infection ; however, in recent years, community-acquired infections have also gained attention. The definitive diagnosis of infectious colitis requires direct or indirect evidence of the pathogen, and it is important to perform efficient diagnosis while utilizing new diagnostic methods. Imaging-based diagnosis, including endoscopy, is useful but comes with the risk of misdiagnosis as inflammatory bowel disease.