急性骨髄性白血病加療中のStomatococcus mucilaginosusによる播種性網脈絡膜炎の1例

A case of disseminated retinochoroiditis caused by Stomatococcus mucilaginosus following chemotherapy for acute myeloid leukemia

要約　目的：Stomatococcus mucilaginosus（Rothia mucilaginosa）は口腔内や咽頭腔などの消化管の常在菌で，日和見感染の起因菌として知られている。同菌によると思われる播種性網脈絡膜炎の1例を報告する。

症例：75歳，男性。急性骨髄性白血病の寛解導入療法中に発熱し，血液培養からStomatococcus mucilaginosusが検出され，同菌による敗血症として加療されていた。好中球減少期の免疫不全下にあった。飛蚊症の訴えで眼科を初診。

所見：視力は右（0.8p），左（0.7）で，両眼底に播種性の黄白色の網膜下浸潤病巣と軽度の斑状網膜出血と硝子体混濁があった。光干渉断層計では網脈絡膜の波打ち所見を認めた。すでに抗菌薬と抗真菌薬の加療中であり，眼科初診後の血液培養と前房水からは菌は検出されなかった。抗菌薬の点滴加療で，解熱とともに眼底の病変は徐々に消退し，播種性の網膜萎縮瘢痕を残した。

結論：Stomatococcus mucilaginosusが免疫不全下に血行性に脈絡膜に至り，免疫回復時に播種性の網脈絡膜病巣を形成したと考えられた。

Abstract　Background：Stomatococcus muciginosus is an indigenous bacterium in the digestive tract, oral cavity and pharynx. It may cause opportunistic infection in immunosuppressed persons.

Purpose：To report a case of disseminated retinochoroiditis caused by Stomatococcus mucilaginosus.

Case：A 75-year-old man under remission induction therapy for acute myeloid leukemia developed sepsis with fever. He was at immunodeficiency with leucopenia. The blood culture revealed Stomatococcus mucilaginosus, then he was treated by antibiotics. He presented floaters in both eyes.

Findings and Clinical Course：Corrected visual acuity was 0.8 in the right eye and 0.7 in the left. Both eyes showed disseminated subretinal white spots with hemorrhagic patches in the retina and vitreous opacity. Optical coherence tomography showed undulated chorioretinal border. Further blood culture or polymerase chain reaction was negative. Fever and signs of ocular infection subsided following antibacterial and antifungal treatments, leaving numerous retinochoroidal atrophic foci.

Conclusion：The present case illustrates that metastatic choroiditis was caused by Stomatococcus mucilaginosus due to suppressed immunity.