Purpose:
While the efficacy of prophylactic antibiotics after intravitreal injection is increasingly controversial, the use of fluoroquinolone antibiotics after injection remains the standard of care. Examination of bacterial culture sensitivities in cases of post-injection endophthalmitis could provide guidance in prophylactic antibiotic selection.
Methods:
A retrospective chart review of all cases of endophthalmitis after intravitreal injection was performed for all patients presenting to a tertiary referral eye hospital between 2006 and 2010. Data included patient demographics, reason for intravitreal injection, medicine injected, source of culture, and susceptibility profiles for positive bacterial cultures. An antibiogram was constructed from all positive cultures. A cost-benefit analysis was also performed comparing the number needed to treat and economic impact of fluoroquinolone antibiotic choice.
Results:
A total of 35 cases of endophthalmitis after intravitreal injection occurred during the four year period observed. Fifty-four percent (54%) of endophthalmitis cultures grew specific bacteria. Fifty percent (50%) of cultured organisms were susceptible to cheaper, older generation fluoroquinolones (FQ) (ciprofloxacin and ocufloxacin) while 67% were susceptible to more expensive, newer FQ (moxifloxacin, levofloxacin, and gatifloxacin). Of the patients susceptible to newer FQ, 100% were susceptible to one of the older FQ. The numbers needed to treat in a head-to-head comparison ranged between 3 and 10.
Conclusions:
Endophthalmitis after intravitreal injection remains a rare but often catastrophic complication of intravitreal injection, and every effort should be made to reduce risk of this complication. The low rates of endophthalmitis combined with the marginal benefit of using more expensive FQ antibiotics could yield a multi-million dollar savings by using less expensive prophylactic medications. Given the antibiotic susceptibilities of endophthalmitis after intravitreal injection, treatment of patients with more expensive, newer FQ medications places an unnecessary cost burden on our healthcare system and contributes to growing antibiotic resistance.
Keywords: endophthalmitis • injection • bacterial disease