Restoring vision after cat bite: a case report on successful diagnostic and therapeutic regimen for Capnocytophaga endophthalmitis.

Background: Capnocytophaga is a bacterium frequently found in the oral flora of dogs and cats (e.g. Capnocytophaga canimorsus) and humans (e.g. Capnocytophaga gingivalis). Among Capnocytophaga related ocular infections, fulminant endophthalmitis is a rare but sight-threatening clinical manifestation.

Case presentation: A 35-year-old previously healthy patient presented after a cat bite into the left upper and lower eyelid and nasal part of the conjunctiva of the left eye. At initial consultation, the corrected visual acuity was 0.8 in decimal scale and a detailed clinical examination revealed no evidence of ocular penetration. However, daily follow-up examinations under local therapy revealed a progressive intraocular inflammation, therefore the decision was made to perform a diagnostic vitrectomy with intravitreal and systemic antibiotic treatment. Capnocytophaga felis was detected as the cause of endophthalmitis and the initiated treatment resulted in quick morphological and functional recovery of the left eye. After surgery of secondary cataract, visual acuity improved from hand motion preoperatively to 1.0 postoperatively.

Conclusions: Early recognition as well as prompt and effective treatment of animal bite associated endophthalmitis is essential for good visual recovery and functional outcome. Furthermore, this case highlights the importance of daily follow-up examinations, even in the absence of signs of ocular penetration and intraocular inflammation, to enable prompt and effective treatment initiation. Given the negative results in bacterial culture, we additionally emphasize the value of sequencing-based microbiological diagnostics in unclear cases.