Comparison of the most common isolates of postoperative endophthalmitis in South Korea; Enterococcus species vs coagulase-negative staphylococci

BACKGROUND To compare the related factors or manifestations of the two most common isolates of post-operative endophthalmitis, which were Enterococcus spp. and coagulase-negative staphylococci (CNS) in South Korea. METHODS Medical records were reviewed for cases of post-operative endophthalmitis caused by Enterococcus spp. and CNS at eight institutions between January 2004 and July 2010. Various factors including age, sex, residence, systemic diseases, smoking and drinking history, and best corrected visual acuity, and length of time between causative intraocular surgery and symptom development were compared between the two groups. RESULTS The total number of post-operative endophthalmitis cases was 128 and in 116 cases, microbiological culture tests from the aqueous humor or vitreous were performed. Among these cases, 67 (57.8%) were culture proven. Among these 67 cases, 19 (28.4%) were caused by Enterococcus spp., 14 (20.9%) were caused by Staphylococcus epidermidis endophthalmitis, and 5 (7.5%) were caused by other CNS spp. Age, sex, causative procedure, past medical history, social history, and laterality were not different in the two groups. Mean initial and final visual acuity were significantly worse in the Enterococcus spp. endophthalmitis group than in the CNS group (p = 0.049, 0.042, respectively). Length of time between the causative procedure and symptom development was significantly shorter in cases of Enterococcus spp. endophthalmitis (p = 0.004). CONCLUSIONS Enterococcus spp. induce more severe and rapid-onset postoperative endophthalmitis than CNS. Infectious endophthalmitis developed within 2 days after cataract operation could be caused by Enterococcus spp. and have chance to be poor prognosis in South Korea.