Endophthalmitis Isolates and Antibiotic Susceptibilities: A 10-Year Review of Culture-Proven Cases

We read with great interest the recent article from Schimel and associates on the important topic of antibiotic susceptibility of pathogens isolated in endophthalmitis cases.

In particular, we commend the authors for reporting a significant increase in bacterial resistance to fluoroquinolones that might confirm fears concerning the possible loss of an effective therapeutic weapon for the treatment of this potentially blinding disease. A further interesting indication related to the efficacy of vancomycin (100% of gram-positives), confirming the findings of a recent article. However, a 1.5% vancomycin resistance rate has been reported in a further recent large study.

We also respectfully highlight that valuable information is lacking. The study included eyes with any type of infectious endophthalmitis, and this explains why 16% of cultures isolated fungi that would be exceptionally rare following intraocular surgical procedures. We invite the authors to provide details on the type of endophthalmitis cases they studied (secondary to cataract surgery, to other intraocular surgical procedure, to trauma, or to systemic infectious disease) and the relative frequency. In association with additional details regarding the type-related microbial profile, this information would certainly be appropriate if a main purpose of the authors was to “optimize the prevention of endophthalmitis using periprocedural antibiotics,” which would likely apply to surgical interventions only. Likewise, it would be imperative in our view to describe the antibiotic prophylaxis measures for pseudophakic endophthalmitis prevention employed at the authors’ institution, if any. In fact, it could be argued that the significant rise in fluoroquinolone resistance found by the authors in more recent years might just be a bias, owing to a massive use of these chemotherapeutic agents in perioperative prophylaxis. That is, are infections sustained by pathogens resistant to fluoroquinolones more common because these antibiotics were effective at preventing a clinical infection in the vast majority of eyes contaminated by bacteria sensitive to fluoroquinolones? Similarly, the intracameral administration of cefuroxime at the time of cataract surgery changes the susceptibility patterns of the isolates from culture-proven pseudophakic endophthalmitis, as previously discussed. In the first of the possible scenarios, fluoroquinolones should still be considered as a valuable option in prophylaxis despite being poorly effective once the infection does develop. In contrast, their use might be discouraged either for prophylaxis or for treatment should a true higher resistance rate to fluoroquinolones be demonstrated.

Additional points of interest are the timing of pseudophakic endophthalmitis development in the studied eyes (from the time of cataract surgery) and the rate of positive cultures over clinically diagnosed endophthalmitis at the authors’ institution.

Finally, it is not clear whether some of the positive cultures were polymicrobial.

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Jan 9, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on Endophthalmitis Isolates and Antibiotic Susceptibilities: A 10-Year Review of Culture-Proven Cases

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