Endophthalmitis risk drops in intracameral antibiotics study

Take-home

Universal use of intracameral antibiotics can nearly eliminate postoperative endophthalmitis, relates one ophthalmologist.

Dr. ShorsteinBy Fred Gebhart; Reviewed by Neal H. Shorstein, MD

Walnut Creek, CA-Intracameral antibiotics work.

That is the key message from a study of more than 16,000 cataract surgeries performed by 14 ophthalmologists at a single Kaiser Permanente facility in Northern California.

Using intracameral cefuroxime in most patients produced a two-fold reduction in endophthalmitis. Extending intracameral antibiotics to 100% of patients produced a 22-fold reduction in postoperative infections.

“The take-home message for me is to use intracameral antibiotics in 100% of patients,” said lead author Neal H. Shorstein, MD, ophthalmologist and associate chief of quality for Kaiser Permanente in Walnut Creek, CA. “Intracameral antibiotic injection works in the United States as it was demonstrated to work in the large European study several years ago.”

Kaiser facility results

The Kaiser Permanente results were similar to results from a large multicenter trial in Europe published in 2006 and 2007.

The researchers reviewed 16,264 consecutive phacoemulsification surgeries performed by 14 different surgeons at the Kaiser Permanente facility in Walnut Creek, CA, from 2007 to 2011.

The study compared three different time periods:

·      No intracameral antibiotics.

·      Intracameral cefuroxime in patients who were not allergic to the agent and did not have posterior capsule rupture.

·      One-hundred percent use of either intracameral cefuroxime, moxifloxacin, or vancomycin.

 Before the use of intracameral antibiotics, there were nine cases of endophthalmitis in 2,878 surgeries, a rate of 3.13 per 1,000. Internal quality review found that there was no identified environmental cause and no trends by surgeon. Laboratory culture identified one case of coagulase negative Staph, one Strep pneumoniae, one Strep viridans, and six patients with clinically confirmed infection but no culture growth.

After results from the European trial were published, all 14 surgeons added intracameral cefuroxime to their usual antibiotic regimen except in patients with an allergy to a penicillin or cephalosporin, or posterior capsular rupture.

Five of the surgeons also switched from tobramycin drops postoperatively to gatifloxacin. Three surgeons stopped prescribing eye drops altogether for patients with uncomplicated surgery who received intracameral cefuroxime. The practice change was instituted in September 2007.

The results were striking: nine cases of endophthalmitis in 6,278 surgeries, a two-fold decrease from the initial period. But the decrease to an infection rate of 1.43 per 1,000 was not statistically significant (p = 0.09).

Six of the nine infections occurred in patients who had not received intracameral cefuroxime, Dr. Shorstein noted.

Four had an allergy to cephalosporin, and two had posterior capsular rupture. Culture resulted in three cases of coagulase negative Staph, one methicillin-resistant Staph aureus, one Enterococcus faecalis, and four with no growth.

An additional practice change

A second practice change was instituted in December 2009. All surgeons used an intracameral antibiotic in all patients, including those with posterior capsular rupture.

Cefuroxime remained the default agent, but moxifloxacin and vancomycin were added for patients who were allergic to cephalosporin and fluoroquinolones, respectively. There was no change in gatifloxacin prescribing.

“Then we found that we had only one infection in 7,108 surgeries, and it told us that using intracameral antibiotics in every single patient would give us the lowest endophthalmitis rate in our population of patients,” Dr. Shorstein said.

“The real surprise was the degree of difference between these two study periods,” he said. “We saw a ten-fold decrease from the period when we were using intracameral cefuroxime in most patients to when we were injecting an intracameral antibiotic by protocol in every single patient. That was a very pleasant surprise.”

It was also a statistically significant surprise. The ten-fold decrease in endophthalmitis compared with using intracameral endophthalmitis in some patients produced an infection rate of 0.14 per 1,000 (p < 0.01).

Instituting protocol

“Instituting our protocol for 100% intracameral antibiotics produced an overall 22-fold decline in endophthalmitis,” Dr. Shorstein said.

In the very few patients who received an injection and still went on to develop endophthalmitis, the final vision for each was   20/30, excluding a single patient with post-exudative age-related macular degeneration. There were no adverse events associated with the injections.

This antibiotic protocol is similar to surgical protocols that call for the use of antibiotic prophylaxis against surgical site infection not more than 60 minutes before the initial incision.

With regard to the concern for selecting out resistant organisms, intracameral antibiotic use is probably   less likely to cause this, Dr. Shorstein noted.

Intracameral injection is a one-time use in a tissue that is largely isolated from the rest of the body as well as from the outside environment.

“I haven’t seen any comparative studies,” he said, “but my guess is that the risk of emerging resistance from this one-time, high-concentration application in a relatively confined environment is much lower than in the case of using multiple applications of a topical antibiotic.

“The injection of antibiotic is very easy,” Dr. Shorstein added. “It is quick and there really isn’t any additional skill set necessary to adopt this practice.”

Neal H. Shorstein, MD

E: neal.shorstein@gmail.com

Dr. Shorstein did not indicate any proprietary interest in the subject matter.

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