Endophthalmitis Caused by Streptococcal Species: Clinical Settings, Microbiology, Management, and Outcomes – Accepted Manuscript

Abstract: Purpose: To report the clinical settings, antibiotic susceptibilities, and outcomes of endophthalmitis caused by Streptococcus species.Study Design: Retrospective, observational case series.Methods: Single-center study evaluating all patients with culture-positive endophthalmitis caused by Streptococcus species between January 1, 2000 and December 31, 2011.Results: Study criteria were met by 63 patients. The most common clinical settings were bleb-associated (17, 27%), post-intravitreal injection (16, 25%), and post-cataract surgery (13, 21%). The isolates were S. viridans (47, 71%), S. pneumoniae (13, 21%), and β-hemolytic Streptococci (5, 8%). Sixty (95%) of 63 isolates were susceptible to vancomycin, 47 (98%) of 48 to ceftriaxone (third generation cephalosporin), and 57 (93%) of 61 to levofloxacin (third generation fluoroquinolone). Between the first and second half of the study period, the minimal inhibitory concentration (MIC) of antibiotics required to inhibit 90% of isolates increased by 1.5-fold for ceftriaxone and 2-fold for levofloxacin, and remained the same for vancomycin. Initial treatment was vitreous tap (49, 78%) or pars plana vitrectomy (14, 22%); all received intravitreal antibiotics. Visual acuity outcomes were variable; best corrected visual acuity (BCVA) was ≥20/400 in 16 (25%) patients and <20/400 in 47 (75%) patients. Evisceration/enucleation was performed in 16 (25%) patients.Conclusion: Streptococcus isolates generally had high susceptibility rates to commonly used antibiotics. Higher antibiotic MICs were required to inhibit 90% of isolates in vitro in the second half of the study period compared to the first half. Despite prompt treatment, the majority of patients had poor outcomes.