Post-surgical versus post-intravitreal injection endophthalmitis: changing patterns in causative flora

Importance Endophthalmitis is a serious complication of intraocular procedures: knowledge of its causative organisms and outcomes may guide prevention and treatment. Background To determine the outcomes and spectrum of causative organisms in acute post-procedural endophthalmitis. Design A retrospective observational case series performed at a tertiary referral hospital during the period 1 July 2012 to 31 July 2017. Participants Two hundred and forty-eight patients diagnosed with acute (<= 6 weeks post-inciting event) endophthalmitis. Methods Chart review of microbiological and clinical data. Main Outcome Measures The main outcome measure was odds of any improvement in visual acuity (3 months versus presentation). Secondary outcomes included causative organism, likelihood of vitrectomy and likelihood of evisceration. Results One hundred and ninty cases were post-cataract surgery or post-intravitreal injection (49 and 141, respectively). Causative organisms were identified in 45% of post-cataract surgery and 54% of post-injection cases (OR = 0.69; P = 0.61). Staphylococcus epidermidis was the most frequent causative organism. Streptococcus species accounted for 32% of post-surgical and 7% of culture-positive post-injection cases (OR = 6.63; P = 0.02). At 3 months, 81% of post-surgical and 84% of post-injection cases had improved BCVA over presentation (OR 0.59; P = 0.61). Conclusions and Relevance S. epidermidis is the most common causative organism. In contrast to other studies, we did not find evidence for an increased odds of Streptococcus spp. endophthalmitis following intravitreal injection. This may in turn reflect guideline-driven changes in practice.