─最近注目される腸管感染症─ヒト腸管スピロヘータ症

Human Intestinal Spirochetosis

要旨●ヒト腸管スピロヘータ症（human intestinal spirochetosis；HIS）の自験例43例について臨床的検討を行った．41例は生検組織またはEMR標本のHE染色で偽刷子縁の所見により，2例は内視鏡検査時に吸引した腸液の直接塗抹で診断された．症状の有無別では無症状例が31例，有症状例が12例であった．生検は主にポリープやびらんから採取され，組織診断は低異型度管状腺腫13例，過形成性ポリープ8例，炎症性変化7例，過形成性結節4例であった．有症状12例中9例は他の疾患が判明し，3例はアメーバ性大腸炎を合併していた．他の原因疾患がみられなかった3例の内視鏡所見は，右側結腸を中心とした半月ひだの浮腫と発赤であった．その内2例では慢性下痢がみられており，腸液の直接塗抹でHISと診断され，遺伝子解析でBrachyspira pilosicoli（BP）が同定された．抗菌薬による治療は1例で行われたのみで，他の症例は無治療で症状が改善していた．HISについての文献的考察を行った．

　We experienced 43 cases of intestinal spirochetosis in our hospital. Forty-one were diagnosed based on the appearance of a “pseudo-brush border” during the microscopic analysis of biopsy or EMR specimens, and 2 were diagnosed based on the analysis of a direct smear of the intestinal fluid collected during colonoscopy. Thirty-one cases were asymptomatic and 12 were symptomatic. Biopsy was mainly obtained from polyps or erosions, and histological diagnosis were tubular adenoma with mild atypia in 13 cases, hyperplastic polyps in 8 cases, inflammatory changes in 7 cases, and hyperplastic nodules in 4 cases. Among the 12 symptomatic patients, 9 were determined to have other causes, including 3 with amebic colitis. In all the 3 cases in which other causes were not identified, colonoscopy showed edematous mucosa and erythema on semilunar folds, mainly at the right side of the colon. Two of the 3 patients complained of chronic diarrhea, and spirochetes were observed on the direct smear of the intestinal fluid aspirated during colonoscopy ; Brachyspira pilosicoli was identified by genetic analysis in both cases. An antimicrobial was administered in only 1 case, and the other cases recovered without treatment.