徳洲会福岡徳洲会病院臨床検査科Department of Clinical Laboratory, Fukuoka Tokusyukai Medical Center
目的：Klebsiella oxytoca腸炎と他の細菌性腸炎の超音波画像や臨床的特徴を比較することで，K. oxytoca腸炎が鑑別可能かを検討した．
対象と方法：2009年9月～2015年8月までに超音波検査（US）を施行した急性腸炎患者で，上行結腸の第2～3層主体の連続性・びまん性壁肥厚を呈し，かつこれらのうち便培養検査にて病原菌が検出された124名（平均年齢26.2±17.0歳，男71名：女53名）をレトロスペクティブに検討した．便培養結果からStaphylococcus aureus群，Campylobacter spp.群，Salmonella spp.群，diarrheagenic Escherichia coli群，enterohemorrhagic E. coli（EHEC）群，K. oxytoca（KO）群の6群に分け，各細菌群の臨床的特徴，最大壁肥厚径や腸管罹患範囲の比較，KO群とEHEC群の超音波画像の比較などを行った．
結果と考察：KO群とEHEC群は同等の最大壁肥厚径を有し［KO群：11.6±1.3 mm （n＝7），EHEC群：13.4±2.9 mm（n＝13）］，他の細菌群よりも有意に高値であった（p＜0.05）．すなわち，目安として1 cmを超えるような高度な右側大腸壁の肥厚を呈する場合は，EHECだけではなくK. oxytocaによる腸炎を想定する必要がある．また，すべての菌群において上行結腸から横行結腸までの罹患範囲が最も多いという同様の傾向を示したことから，罹患範囲からK. oxytoca腸炎を鑑別することは困難であった．KO群の臨床的特徴は高い発症年齢，高頻度の血便・下血，短い発症–来院時間，高い抗生物質使用歴であったことから，これらもK. oxytoca腸炎を鑑別する一助になり得ると考えられた．
結論：K. oxytoca腸炎は，右側大腸の高度な壁肥厚（参考値：＞1 cm）を有するという超音波所見があり食中毒を思わせる摂食歴がない場合に疑われ，それに加え抗生物質使用歴があれば抗生物質起因性出血性腸炎を疑うことができる可能性がある．
Purpose: The purpose of this study was to evaluate clinical findings of Klebsiella oxytoca colitis and identify its diagnostic possibility by ultrasonography (US).
Subjects and Methods: From September 2009 to August 2015, 124 patients [average age: 26.2±17.0 years (71 males and 53 females)] with symptoms of acute colitis underwent US, and their stool samples were cultured for Staphylococcus aureus, Campylobacter spp., Salmonella spp., diarrheagenic Escherichia coli, enterohemorrhagic E. coli (EHEC), and K. oxytoca. The maximum colonic wall thickness and diameter, extent of inflammatory lesions, and findings on US images were compared between the six bacterial colitis groups. All patients underwent US within 4 days from symptom onset.
Results and Discussion: (1) Diffuse wall thickening (mainly in the third layer, which is the most echogenic layer, corresponding to the submucosa) in the right-sided colon was detected in US in all patients. (2) The colonic wall was significantly thicker in patients with K. oxytoca and EHEC colitis than in those with other bacterial colitis types [K. oxytoca colitis (n＝7): 11.6±1.3 mm and EHEC colitis (n＝13): 13.4±2.9 mm; p＜0.05]. Thus, the results indicated that right-sided colitis with severe wall thickness (reference values: ＞1 cm) was caused by either K. oxytoca or EHEC. (3) The ascending colon and transverse colon were usually affected in all the groups, and no relationship was apparent between the bacterial colitis type and extent of inflammatory lesions. (4). The clinical features of K. oxytoca colitis were a relatively high age (43.4±13.4 years), high frequency of bloody stool or melena (86%), antibiotic use history (4/7), and shortened onset-to-door time (＜1 day), it was considered that these also features can be a help to diagnose K. oxytoca colitis.
Conclusion: The present study’s results suggest that the maximum thickness of the colonic wall obtained in US and the positive antibiotic/food history allow the differentiation of K. oxytoca colitis from other bacterial colitis types.
Key words: ultrasonography; Klebsiella oxytoca; antibiotic-associated hemorrhagic colitis
© 2016 一般社団法人日本超音波検査学会© 2016 Japanese Society of Sonographers
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