抗生物質起因性腸炎の臨床像と鑑別診断

Clinical Findings and Differential Diagnosis of Antibiotic-Induced Colitis

要旨　抗生物質起因性腸炎は偽膜型と非偽膜型に分類される．偽膜性大腸炎は重篤な疾患を有する高齢者に好発し，血便・腹痛はやや少なく，セフェム系・注射・多剤投与，C.difficile毒素陽性例が多い．非偽膜型ではⅠ（びまん出血）型は若年者に好発，血性下痢・腹痛が高率，原因疾患は感冒が多く，合成ペニシリン・内服・単剤投与が多い．Ⅱ（縦走潰瘍）型はセフェム系投与が多い以外はⅠ型に類似，Ⅲ（アフタ）型は年齢，症状，抗生物質の種類・投与経路，好発部位，C.difficile毒素陽性例の存在など偽膜性大腸炎に類似，Ⅳ（非特異）型は様々な病態のものが含まれ特徴的なものはない．鑑別診断は抗生物質投与の有無，便細菌学的所見が重要であるが内視鏡的には偽膜性大腸炎では潰瘍性大腸炎，クラミジア直腸炎，アメーバ赤痢，びまん出血型や縦走潰瘍型では虚血性大腸炎や腸管出血性大腸菌O157による腸炎，アフタ型や非特異型では各種感染性腸炎と鑑別を要する．

　Antibiotic-induced colitis is classified into pseudomembranous colitis and 4 types of nonpseudomembranous colitis according to endoscopic findings. Type Ⅰ (diffuse, bleeding lesion) showed the highest incidence. The features were : high occurrence among young people, high occurrence of bloody diarrhea and abdominal pain, high frequency of the common cold as the underlying disease, and many of the cases had been given a single administration of synthetized penicillins orally. Type Ⅱ (longitudinal ulcer) was similar to Type Ⅰ, except that a considerable number of the cases had received cefems. Type Ⅲ (aphthoid lesion) was similar to pseudomembranous colitis in many respects, such as the age of patients, symptoms, type of antibiotics, route of administration, site of predilection and existence of Clostridium difficile Dl toxin positive cases. Type Ⅳ (nonspecific lesion) which can not be classified as Ⅰ, Ⅱ, Ⅲ type endoscopically included from mild to severe cases. In endoscopic findings, occasionally, pseudomembranous colitis is similar to ulcerative colitis, Chlamydia proctitis and amoebic colitis. Types Ⅰ and Ⅱ are sometimes similar to ischemic colitis and hemorrhagic colitis by Escherichia coli O157, and Types Ⅲ and Ⅳ are similar to various forms of infectious colitis. History of the administration of antibiotics and bacteriological examination are necessary for differetial diagnosis.