Microbiology and visual outcomes of culture-positive bacterial endophthalmitis in Oxford, UK

Purpose To review the microbiology of culture-positive cases of bacterial endophthalmitis, and to correlate this with visual outcomes. Method Case notes were reviewed for culture-positive cases of bacterial endophthalmitis over a period from November 1999 to June 2012. Cases were identified retrospectively using a local database. The Fisher exact test was used for statistical analysis. Results Of the 47 cases of culture-positive bacterial endophthalmitis identified, 81 % occurred postoperatively, 11 % followed intravitreal injection, 6 % had an endogenous source and 2 % followed ocular trauma. Eighty-seven percent of bacteria cultured were Gram-positive. The most commonly identified organisms were coagulase-negative Staphylococci (47 %) and Streptococcus spp . (30 %). Patients were treated with intravitreal vancomycin and either amikacin or ceftazidime. All Gram-negative isolates were sensitive to aminoglycosides and ceftazidime, and all Gram-positive isolates were vancomycin-sensitive. Final visual acuity (VA) was 6/12 or better in 41 % of cases and counting fingers (CF) or worse in 30 %. Endophthalmitis caused by Streptococcus spp. was associated with a poorer final VA (OR for CF or worse = 14.9, P < 0.01). Cases caused by coagulase-negative Staphylococci had a better visual outcome (OR for VA of 6/12 or better = 5.7, P = 0.013). Five eyes were eviscerated or enucleated. Infection with Haemophilus influenzae was strongly associated with this outcome (OR = 57, P < 0.01). Conclusion Over the time period of this study there was no evidence of emerging resistance to empirical antibiotics which are commonly used for the treatment of bacterial endophthalmitis. Infection with coagulase-negative Staphylococci was associated with a good visual outcome, whilst infection with Streptococcus spp. or Haemophilus influenzae was associated with a poor visual outcome.