歯科治療を契機に発症したB群連鎖球菌による内因性眼内炎の1例

A case of endogenous endophthalmitis after dental treatment caused by group B Streptococcus

要約　目的：内因性眼内炎は眼外に感染巣を伴い，血行性転移により眼内炎を呈する疾患である。高齢者や糖尿病患者に多く，肝膿瘍やカテーテル関連感染などが原因として多い。今回，歯科治療後に発症した内因性眼内炎の生来健康な女性例を報告する。

症例：患者は47歳，女性。歯科治療中であったが，それ以外の既往はなかった。2日ほどで進行する右眼の視力低下を自覚し順天堂大学医学部附属浦安病院眼科を受診した。初診時の矯正視力は右手動弁と低く，前眼部には前房蓄膿や前房内細胞を認めた。眼底所見は硝子体混濁と後極部付近に黄白色の滲出斑を認めた。光干渉断層計で同部位は網膜下の隆起性病変を伴っていた。全身CTでは明らかな感染巣はなかったが，血液検査で炎症反応上昇を認めたため，入院のうえでメロペネム水和物点滴を開始した。しかし，翌日夕方頃から眼内炎症が増悪したため硝子体切除術を行った。術中所見は著明な硝子体混濁と広範な網膜内膿瘍，網膜剝離を認めており，完全な復位は困難であった。手術時に採取した硝子体液培養より口腔内常在菌であるB群連鎖球菌を検出し，他の感染巣もないことから，歯科治療を契機に発症した内因性眼内炎と診断した。術後も抗菌薬点滴を継続し眼内炎症は軽減したが，右矯正視力は手動弁にとどまった。

結論：生来健康な成人であっても，歯科治療を契機に内因性眼内炎を起こすことがある。B群連鎖球菌のような視力予後不良な起因菌も存在するため，早めに手術治療も検討すべきである。

Abstract　Background：Endogenous endophthalmitis develops following hematogenous spread of an extraocular infection. This condition is common in the elderly and diabetic patients, and often occurs secondary to liver abscess or catheter-related infections. In the present study, we report a case of endogenous endophthalmitis in an innately healthy woman that developed after dental treatment.

Case：A 47-year-old woman with no significant medical history underwent dental treatment. She came to our clinic because she was aware of loss of vision in her right eye, which progressed over two days. Her corrected visual acuity was hand motion in the right eye. Slit-lamp examination showed cells in the anterior chamber and hypopyon. Fundoscopy revealed vitreous opacity and a yellowish-white exudate near the posterior pole. Optical coherence tomography revealed an elevated subretinal lesion in the same area. A CT scan of the whole body showed no obvious focus of infection, although the results of blood tests showed an elevated inflammatory response. Hence, the patient was admitted to the hospital and intranvenous meropenem were started. However, the intraocular inflammation had worsened by the following evening, and therefore she underwent vitrectomy. Intraoperative findings showed marked vitreous opacities, extensive intraretinal abscess formation, and retinal detachment, making complete recovery difficult. Group B streptococcus, a common oral bacterium, was detected in the vitreous humor specimen obtained for culture, and a diagnosis of endogenous endophthalmitis triggered by dental treatment was established. Postoperatively, intravenous antibiotic treatment were continued, which resulted in decrease in the intraocular inflammation, although the corrected visual acuity in her right eye remained at the finger counting level.

Conclusion：Endogenous endophthalmitis as a result of dental treatment can develop even in healthy adults. In such cases, prompt surgical treatment should be considered as causative organisms, such as group B streptococci, are associated with a poor visual prognosis.