Purpose: To report the clinical settings, antibiotic susceptibilities, and outcomes of endophthalmitis caused by Streptococcus species.
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 (n = 17; 27%), after intravitreal injection (n = 16; 25%), and after cataract surgery (n = 13; 21%). The isolates were Streptococcus viridans (n = 47; 71%), Streptococcus pneumoniae (n = 13; 21%), and β-hemolytic Streptococci (n = 5; 8%). Sixty (95%) of 63 isolates were susceptible to vancomycin, 47 (98%) of 48 isolates were susceptible to ceftriaxone (third-generation cephalosporin), and 57 (93%) of 61 isolates were susceptible to levofloxacin (third-generation fluoroquinolone). Between the first and second half of the study, the minimal inhibitory concentration 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 was 20/400 or better in 16 (25%) patients and worse than 20/400 in 47 (75%) patients. Evisceration or enucleation was performed in 16 (25%) patients.
Conclusions: Streptococcus isolates generally had high susceptibility rates to commonly used antibiotics. Higher antibiotic minimal inhibitory concentrations were required to inhibit 90% of isolates in vitro in the second half of the study period compared with the first half. Despite prompt treatment, most patients had poor outcomes.
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