尿路結核治療後に非結核性抗酸菌が尿から分離された1例

Abstract

70歳代男。患者は頻尿と残尿感を主訴とした。膿尿を認めて尿路感染症と診断され, セフジニルを1週間投与されたが, 症状ならびに検尿所見は改善しなかった。膀胱鏡検査では膀胱粘膜の広範な発赤, 浮腫が認められ, 尿細胞診はclass IIであった。一方, DIPおよびCTでは左側の不完全重複腎盂尿管とそれぞれの拡張所見がみられ, 尿中結核菌PCR検査は陽性であった。以上より, 本症例は尿路結核と診断され, Isoniazid, rifampicin等4剤による治療を6ヵ月間施行した結果, 自覚症状と膿尿は消失し, 尿中結核菌PCR検査も陰性となった。だが, 抗酸菌培養検査は2回続けて陽性で, Mycobacterium fortuitum(M. fortuitum)が分離された。このM. fortuitumに対する抗結核薬の薬剤感受性試験では全てが耐性で, 尿路結核治療後は左不完全重複腎盂尿管のうち上方腎盂の形態は正常化したが, 下方腎盂の拡張は改善しなかった。以後, M. fortuitum尿路感染に伴う自覚症状はないことから定期的な抗酸菌培養と腎超音波による経過観察とした。

A 70-year-old male who complained of urinary frequency and a feeling of incomplete emptying was admitted to our hospital. Imaging findings showed dilation of the left renal pelvis and ureter. He was diagnosed as having urinary tuberculosis because a positive urinary Mycobacterium tuberculosis result was obtained by polymerase chain reaction (PCR). He was treated with a combination of the antituberculosis agents isoniazid, rifampicin, pyrazinamide and ethambutol for six months. The symptoms and pyuria disappeared and M. tuberculosis was negative by PCR; however, Mycobacterium fortuitum was isolated by culture. Due to asymptomatic urinary tract infection by the multidrug resistant M. fortuitum, he was followed up with observation. Currently, he remains unchanged with regard to symptoms and imaging examination. M. fortuitum is a nontubercular mycobacterium, and clinical relevance between urinary tract infection and M. fortuitum has rarely emerged. However, we should be aware that nontubercular mycobacteria such as M. fortuitum can infect the urinary tract, especially in immunocompromised patients.