May 2012

 

COVER FEATURE

 

Perioperative pharmacology

Update on antibiotics: No clear-cut regimen yet


by Jena Passut EyeWorld Staff Writer

   
Moxifloxacin injection intracamerally

Syringe

Dr. Arshinoff injects moxifloxacin intracamerally to help keep endophthalmitis at bay Source: Steve A. Arshinoff, M.D.

When it comes to the role of pre- and post-op antibiotics in ophthalmic surgical prophylaxis, one thing remains certain: There are no clear-cut answers on how to proceed, and controversy remains about what works best to reduce the risk of post-surgical endophthalmitis.

"In part, it has been a bit of a moving target as procedures and techniques change," said Terrence P.O'Brien, M.D., professor of ophthalmology, Bascom Palmer Eye Institute, Miller School of Medicine, University of Miami. "Despite all efforts pre-operatively to prevent contamination and inoculation of the eye with organisms, they can be recovered from the aqueous humor a surprisingly high percentage of the time, maybe 5-30%. You may have organisms that can be recovered at the conclusion of the case even in a procedure that has been uncomplicated."

The question then becomes what to do about potential organisms that may enter the eye even with the perfect surgery being performed.

"In general, true surgical prophylaxis is supposed to be not using the final greatest guns, but [using] the most basic good coverage," said Lisa B.Arbisser, M.D., adjunct associate professor, John A. Moran Eye Center, University of Utah, Salt Lake City. "Ophthalmologists are unable to pay attention to the dictates of normal surgical prophylaxis because it requires having the minimum inhibitory concentration (MIC) for the appropriate organism at a high enough level prior to making an incision and keeping it at that level throughout the surgery until after the incision is closed."

The MICis the minimum amount of the antibiotic that is needed to inhibit bacterial growth, according to Francis S.Mah, M.D., medical director, Charles T. Campbell Ophthalmic Microbiology Laboratory, University of Pittsburgh School of Medicine.

Dr. Mah said many questions remain surrounding the use of antibiotics for prophylaxis in cataract surgery.

"Even though we think we know a lot, there's still a lot that we don't know," he said. "We don't know what's truly appropriate as far as dosing. There are some people who use topical antibiotics once or twice a day pre-operatively. Some people are injecting intracamerally."

"As far as the true efficacy of these drops, we don't know if these drugs are doing that much or if it's our smaller incisions that are leading to fewer endophthalmitis infections. No one can really separate that out because things have been advancing together. I do think that the evidence is stronger for intracamerals than for topical, though."

Intracameral injections

Ever since a 2006 multicenter collaborative study by the European Society of Cataract & Refractive Surgeons (ESCRS) showed conclusively that the concept of intracameral injections of antibiotics reduces the risk of endophthalmitis more effectively than topical antibiotics alone, U.S. surgeons have begun to adopt the practice, albeit often with a different drug than used in the popular study.

Intracameral injections of antibiotics for prophylaxis in cataract surgery are off-label, like most drug uses in ophthalmology.

"The ESCRS study proved that intracameral antibiotics work very well at reducing infection rates, but the problem was that there was no comparison of one drug to another," said SteveA. Arshinoff, M.D., clinical instructor of ophthalmology, University of Toronto. "It only proved the concept."

In the ESCRS study, intracameralCeftin(cefuroxime, GlaxoSmithKline, Middlesex, U.K.) was used. "The reason cefuroxime has not gained popularity here is that it has to be diluted and mixed, and there's this large concern about improper dilution and developing toxicity and toxic anterior segment syndrome (TASS)," said SamuelMasket, M.D., clinical professor of ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles. Also, cefuroxime doesn't cover the most common pathogen that leads to endophthalmitisStaphylococcus epidermidis.

In the December 2011 Journal of Cataract & Refractive Surgery, Dr. Arshinoff and his colleagues studied whether prophylactic intracameral antibiotics would lessen the incidence of endophthalmitis during sequential bilateral cataract surgery. The researchers reviewed relevant literature and surveyed members of the International Society of Bilateral Cataract Surgeons and discovered that the bilateral approach to surgery did not increase the risk of endophthalmitis. They also concluded that the risk of post-op endophthalmitis was significantly reduced by use of intracameral antibiotics. In Europe, for example, they found a 0.3% incidence without prophylactic intracameral antibiotics and a 0.05% occurrence with their use in unilateral cataract surgery. Dr. Arshinoff mixes 0.2 ccs of 300 micrograms of Vigamox (moxifloxacin hydrochloride ophthalmic solution, Alcon, Fort Worth, Texas)with balanced salt solution (BSS, Alcon).

"It's easy; you take the whole bottle of moxifloxacin, you aspirate into a syringe, and then you aspirate 7 ccs more of BSS, and that's it," he explained.

Dr. Arbisser said she has the patient bring in an unopened bottle of Vigamox and uses that intracamerally.

She has also continued to use topical antibiotics 1 hour pre-op and for a week post-op.

"I continue to do that, even though intracameral Vigamox and Betadine [povidone iodine, Purdue Pharma L.P., Stamford, Conn.] are the reasons I am 10,000 cases in without any endophthalmitis," she said.

Timing is everything

Update on antibiotics article summary

There are no clinical trials surgeons can refer to as a guide for when to start topical prophylactic antibiotics.

Dr. Arshinoff administers topical antibiotics 1 hour before patients are wheeled into the operating suite.

He cited a study in JCRS by Lindsay Ong-Tone, F.R.C.S.C., illustrating that the amount of antibiotics that gets placed in the eye is maximized by giving patients the drops four times during the hour before surgery.

"You also know they got it because you gave it to them," he said, adding that compliance always seems to be a concern.

Dr. Masket said he prescribes topical antibiotics four times a day starting 1 day prior to surgery for routine cases. For patients who are immunologically compromised or who have a Jones lacrimal tube or prosthetic fellow eye, he prescribes systemic Avelox (moxifloxacin, Merck, Whitehouse Station, N.J.) 2 days prior, the day of surgery, and 2 days aftereach one dose of 400 mg. The surgeons agreed that post-op antibiotics haven't been proven to be effective, but they aren't willing, just yet, to stop the regimen on the chance that they are beneficial.

"I think we do it because we're afraid," Dr. Arshinoff said. "Some patients rub their eyes and may make the incisions leak. We may get high enough doses in the eye to kill most bugs by giving them post-op drops."

"Do we need all the topical antibiotics?" Dr. Arbisser asked. "Frankly, there's no evidence that we do, but I haven't been bold enough to stop."

References

Barry P, Seal D,GettinbyG, Lees F, Peterson M, Revie C. ESCRS study of prophylaxis of post-operative endophthalmitis after cataract surgery: Preliminary report of principal results from a European multicenter study. J Cataract Refract Surg. 2006; 32:407-410.

Arshinoff SA, Bastianelli PA. Incidence of postoperative endophthalmitis after immediate sequential bilateral cataract surgery. J Cataract Refract Surg.2011 Dec;37(12):2105-14.

O'Brien TP,ArshinoffSA,MahFS. Perspectives on antibiotics for postoperative endophthalmitis prophylaxis: potential role of moxifloxacin. J Cataract Refract Surg.2007 Oct;33(10): 1790-800.

Endophthalmitis Study Group, European Society of Cataract & Refractive Surgeons. Prophylaxis of postoperative endophthalmitis following cataract surgery: results of theESCRSmulticenter study and identification of risk factors. J Cataract Refract Surg.2007 June;33(6):978-88.

Ong-ToneL. Aqueous humor penetration of gatifloxacin and moxifloxacin eyedrops given in different concentrations in a wick before cataract surgery. J Cataract Refract Surg. 2008 May;34(5):819-22.

Editors' note: Dr.O'Brienhas financial interests with Alcon, Allergan (Irvine, Calif.), and Bausch + Lomb (Rochester, N.Y.).

Contact information

Arbisser: 563-323-2020, drlisa@arbisser.com
Arshinoff: 416-745-6969, ifix2is@sympatico.ca
Mah: 412-647-2211,mahfs@upmc.edu
Masket: architart@aol.com
O'Brien: 561-515-1544, tobrien@med.miami.edu

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