Surgeon: consider the science when choosing antibiotic

CANCUN, Mexico — Ophthalmologists should use science as their main criterion in selecting the best antibiotic to use, said James P. McCulley, MD, FACS, FRCOphth, here at the Central Mexican Cornea and Refractive Surgery Congress.

“Clearly the latest generation fluoroquinolones are going to be the fluoroquinolones of choice,” Dr. McCulley said in an interview with Ocular Surgery News. However, he said, all the scientific data needed to make an informed choice is not yet available for the two newest anti-infectives.

“For comparative purposes we need good human data, where we can get human data. In vitro data can be of good use to us if it’s done with the commercial preparation of the antibiotic, with bacteria that are human ocular isolates and done in an appropriate manner,” Dr. McCulley said.

When asked about the efficacy of the latest generation of fluoroquinolones, Dr. McCulley cautioned that more research is needed and that ophthalmologists must be judicious in their selection. He said, given its limitations, the data now available suggests that one of the two new fluoroquinolones may be superior.

“The data we have today is incomplete, but based on what I have seen the selection between moxifloxacin and gatifloxacin appears to favor moxifloxacin,” he said. “The objective things we can look at — the concentration, the pH, the self-preserving aspects, those are irrefutable. So from a comfort standpoint, a toxicity standpoint, moxifloxacin clearly wins, no question. From a penetration standpoint, or bioavailability standpoint, all theory supports that moxifloxacin would be superior, but we still need the data in humans.”

More information is needed on kill curves of the two newest fluoroquinolones, he said.

“The kill curves are important in determining how long before surgery we should start prophylaxis, and when dealing with an infection, how rapidly we can kill the bug. If we apply those principles to what we have available to us — and here will come my bias — we maybe have 40% of the information we need. We have MICs (minimal inhibitory concentrations) that clearly support the later generation fluoroquinolones being better than prior generations,” he said.

Dr. McCulley also said he gives little weight to animal study data.

“Animal data is only of legitimate use when we cannot get the information from a human,” he said. “There are some animal trials that are interesting, but in general I view them as more supplemental than front line, as many of the things we get from animals we can get from humans. We can get tissue concentrations from humans. When someone gives me animal data and for some reason there’s no human data, I use it as a surrogate. But I want human tears, cornea, aqueous and, ideally, vitreous data.”