Optimal antibiotic regimen still controversial for endophthalmitis prophylaxis

TAKE HOME MESSAGE: Accumulating evidence shows intracameral antibiotics decrease the risk of endophthalmitis after cataract surgery, but questions and concerns remain.

By Cheryl Guttman Krader; Reviewed by said Francis S. Mah, MD

La Jolla, CA-Antibiotic prophylaxis for cataract surgery remains a controversial topic, despite convincing data showing the efficacy of intracameral antibiotic use for reducing the risk of postoperative endophthalmitis, said Francis S. Mah, MD.

“The low rate of postoperative infection and the potential for many different variables to affect the risk make it difficult to conduct an appropriate large-scale clinical trial,” said Dr. Mah, director, corneal and external disease, and co-director, refractive surgery, Scripps Clinic, La Jolla, CA.

The prospective study undertaken by the European Society of Cataract and Refractive Surgeons (ESCRS) provides the best evidence available, and subsequently, the efficacy of intracameral antibiotic prophylaxis has been demonstrated in other prospective studies, Dr. Mah said.

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“However, there are still concerns about that approach and questions about the optimal technique,” he said.

Reviewing the outcomes of the ESCRS study, members of the Infectious Disease Task Force of the American Society of Cataract and Refractive Surgery (ASCRS) concluded that intracameral antibiotic use may be a paradigm shift for endophthalmitis prophylaxis. However, continued research was needed to examine the optimal drug, dose, and method of delivery, as well as the short- and long-term effects.

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In addition, widespread adoption would depend on access to a product that would be safe and simple to use with minimal risk of dilution errors and contamination, Dr. Mah said.

Next: Single-use cefuroxime use

In 2012, single-use cefuroxime for intracameral use became commercially available in some countries in Europe. This product represents a step forward as it significantly reduces the safety concerns associated with extemporaneous preparation.

However, it does not completely eliminate the potential for dilution errors and contamination, and there have been reports of anaphylaxis associated with its use.

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“The risk of an allergic reaction is much lower with cefuroxime compared with penicillin, but it still exists,” Dr. Mah said.

Interestingly, in a survey of ESCRS members published in 2014, only 74% of respondents were always or usually using an intracameral antibiotic in cataract surgery, despite the fact that it is recommended by the ESCRS and various European national ophthalmology societies.

“Many of the respondents still questioned the scientific merit or need for intracameral antibiotic use, but concern over risks associated with compounding the dose was also common,” Dr. Mah said.

Next: Topical antibiotics

No prospective study has ever been conducted to provide direct proof that topical antibiotic use decreases the risk of endophthalmitis. In the ESCRS study, perioperative use of topical levofloxacin was associated with a decreased rate of endophthalmitis, but the benefit did not achieve statistical significance.

Dr. Mah said use of topical antibiotics for endophthalmitis prophylaxis is supported by surrogate evidence derived from microbiology studies demonstrating reduced bacteria counts in cultures grown from conjunctiva and aqueous humor specimens. In addition, there are data from retrospective studies showing benefit.

Despite the lack of definitive evidence demonstrating its efficacy, topical antibiotics are widely used for endophthalmitis prophylaxis, especially in the United States.

Findings from a member survey conducted by the ASCRS Cataract Committee in 2007 showed that 88% of respondents were using a topical antibiotic preoperatively and 98% used a topical antibiotic postoperatively. American surgeons accounted for about three-fourths of the survey participants.

The advanced generation fluoroquinolones have become the most commonly used antibiotics for topical endophthalmitis prophylaxis due to their broader spectrum of antimicrobial activity and superior ocular penetration characteristics compared with earlier generation fluoroquinolones and other alternatives. Dr. Mah noted that regimens vary among surgeons.

However, based on pharmacokinetics and pharmacodynamics data, there are recommendations to initiate treatment 1 to 3 days prior to surgery or to increase the frequency of dosing immediately prior to surgery in order to increase the concentration of antibiotic in the anterior chamber.

Next: Solid recommendations

Certain strategies for reducing risk of postoperative endophthalmitis are well-accepted as standard of care. They include the need to preoperatively identify and treat periocular conditions that have been associated with an increased risk of endophthalmitis-e.g., conjunctivitis, blepharitis, and dry eye.

Meticulous lid draping is also mandatory, recognizing that lid flora are the predominant pathogens in cases of postoperative endophthalmitis, and preoperative antisepsis with povidone-iodine should always be performed.

“The povidone-iodine prep should include not only use of the 10% scrub on the lids and lashes but also placing a drop of the 5% solution in the conjunctival cul de sac for a minimum 5-minute contact time,” Dr. Mah said.

Francis S. Mah, MD

E: mah.francis@scrippshealth.org

This article was adapted from Dr. Mah’s presentation during Cornea Subspecialty Day at the 2014 meeting of the American Academy of Ophthalmology. Dr. Mah is a consultant to Alcon Laboratories, Allergan, Bausch + Lomb/Valeant, Ocular Therapeutix, and PolyActiva.