July 2018

CORNEA

Research highlight
Surveying the field


by Maxine Lipner EyeWorld Senior Contributing Writer


Practitioners in the United States have different first-line treatments for corneal ulcers such as this one.


Those in the United States are more likely to prescribe compounded antibiotic to treat corneal ulcers than their international counterparts.
Source (all): Julie Schallhorn, MD

Differing views on bacterial keratitis treatment

How practitioners treat bacterial keratitis may be tied in part to where they practice, according to Julie Schallhorn, MD, assistant professor of ophthalmology, University of California San Francisco. In a study1 published in BMJ Open Ophthalmology, investigators took a closer look at what practitioners in the United States and internationally do to combat bacterial keratitis.
“The impetus for the study was looking at changing practice patterns, how people incorporate the existing literature, and what they’re seeing in the community in terms of their culture results, as well as looking to see what antibiotics they’re using to treat,” Dr. Schallhorn said. The prior gestalt has been that there’s no difference in outcomes with third and fourth generation fluoroquinolones versus use of compounded antibiotics.

United States vs. international contingent

At the University of California San Francisco, investigators were seeing a lot of Staph aureus ulcers. Spurred by concerns over increasing fluoroquinolone and methicillin resistance, Dr. Schallhorn and fellow investigators had seen their practice patterns drift toward prescribing compounded antibiotics or fluoroquinolones, and they wanted to see what others in the community were doing.
The study involved a survey emailed to all the members of the Cornea Society listserv, Dr. Schallhorn said. “About 10% of the respondents were international providers,” she said. This included providers from all continents.
Survey results were impacted by the practitioner’s locale. “People in the United States were more likely to prescribe compounded antibiotics than the international respondents,” she said. Of the majority of United States respondents, 80% chose fortified antibiotics, while only 31% of international practitioners used fortified antibiotics as their first-line therapy, Dr. Schallhorn noted. “People who were concerned about methicillin resistance were more likely to use vancomycin,” she said. “Those who were concerned about toxicity tended to use vancomycin as a first-line therapy.” This, she explained, is because one problem that can arise with compounded antibiotics is corneal toxicity.
“People in the United States in general favor fluoroquinolones over compounded antibiotics, which may reflect their local practice patterns and the flora that they’re seeing in their corneal ulcers,” Dr. Schallhorn said. “We don’t know exactly, but that’s what we’ve theorized.”
It may be that methicillin resistance is more of an issue in the United States, which may be why American practitioners have been prescribing more fluoroquinolones or more compounded antibiotics. “Or it may be that we have more access to compounded antibiotics, so it’s easer for us to get them,” Dr. Schallhorn said.
Dr. Schallhorn was surprised to see the discordance in rates of prescribing between those in the United States and the international contingent. “I was also surprised to see how high the rate of compounded antibiotic use was,” she said, adding that such antibiotics require more of a practitioner’s attention. This may involve making a lot of calls, filling out more paperwork, and sending the patient to a specialty compounded pharmacy, she explained. “I was surprised that this many people were going through the rigmarole, especially when the best evidence that we have is that fluoroquinolones are equivalent to compounded.”

Clinical ramifications

From a clinical perspective, with approximately 50% of practitioners in the United States using fluoroquinolones as their first-line treatment for corneal ulcers and the other 50% going the compounded route, those who choose one approach or the other have ample company, Dr. Schallhorn pointed out. “I think that especially in areas that have a high rate of methicillin resistance, we should consider redoing a trial to look at fluoroquinolones versus compounded and see what comes out on top.”
Even when there is resistance, practitioners should keep in mind that corneal ulcers are complex, Dr. Schallhorn advised. “Sometimes you can overcome antibiotic resistance with concentrated topicals,” she said. It does raise some questions about whether the current studies are outdated and needed to be updated, she added.
Dr. Schallhorn hopes that practitioners garner reassurance from the study. “The take-home message is that whatever you personally decide to do for your first-line antibiotic choice, there is ample evidence in the literature and in the community that either of the choices are adequate,” she said. For patients who are at higher risk in cases of a resistant organism, especially those with a history of hospitalization, however, physicians might want to think more seriously about going the compounded route, she said.

Reference

1. Austin A, et al. Empirical treatment of bacterial keratitis: an international survey of corneal specialists. BMJ Open Ophthalmol. Epub 2017 Aug 16.

Editors’ note: Dr. Schallhorn has no financial interests related to her comments.

Contact information

Schallhorn: jschallhorn@gmail.com

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