Late diagnosis of Cutibacterium acnes (formerly Proprionibacterium acnes) endophthalmitis and the importance of dual testing with bacterial culture and polymerase chain reaction.

To describe two cases of C. acnes endophthalmitis that reinforce the importance of performing both bacterial culture and 16s polymerase chain reaction when the causative pathogen is unclear or difficult to culture, such as C. acnes. A case of C. acnes endophthalmitis complicated by sub-buckle scleral perforation is illustrated with intraoperative photography. Two-case series. Case 1 describes a case of C. acnes endophthalmitis in a longstanding pseudophakic patient following multiple vitrectomies for recurrent retinal detachment, complicated by sub-buckle scleral perforation. Bacterial culture revealed C. acnes while 16s PCR was negative. Conversely, Case 2 demonstrates a case of chronic endophthalmitis diagnosed one year following cataract surgery. PCR (with repeat tap for confirmation) revealed C. acnes with a negative culture. When the causative pathogen of endophthalmitis is unclear, dual testing of microbial culture and C. acnes 16s PCR improves the diagnostic yield of investigations for fastidious pathogens. C. acnes can present as an indolent or virulent endophthalmitis.