EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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98 98 EW REFRACTIVE March 2012 On reconnaissance for mycobacteria by Maxine Lipner Senior EyeWorld Contributing Editor Putting this stubborn infection on the radar A P patient comes in with symptoms of an infection, and after due considera- tion, most likely you reach for one of the fluo- roquinolones, vancomycin, or per- haps a fungal agent. If you're faced with a mycobacterial infection, how- ever, such an approach will gain you no ground, according to Dalia O. Girgis, M.D., senior resident, department of ophthalmology, University of Wisconsin, Madison. "Mycobacterial infections are quite resistant to typical therapy that might be initiated for normal bacterial infection," Dr. Girgis said. "A lot of the time they are associated with biomaterials, and so often times to actually have resolution of the infection, removal of that bio- material may be required." In fact, results from a recent study that Dr. Girgis conducted on this showed the pivotal role bioma- terials often play here. "We found that around 63% of our infections were associated with some sort of biomaterial," Dr. Girgis said. The most common among these were things such as scleral buckles, punc- tual plugs, and stents for dacryocys- torhinostomy. In the retrospective review study, which was published in the Running the numbers on post-LASIK infectious keratitis ost-LASIK infection tends to be rare, but when it does occur, given the seri- ousness, everyone takes note. In a June 2011 survey of the literature published in Klin Monbl Augenheilkd, investigators set out to get a handle on the most frequent post-LASIK infections. Among the results highlighted here was the most recent ASCRS post-LASIK infectious keratitis survey, in which members of the Society reported 116 post-LASIK infections—an incidence of just 1 in every 2,919 procedures, or 0.035%. Investigators also brought to light infectious keratitis results published by Fernando L. Llovet in the February 2010 issue of Ophthalmology that showed a 0.0084% incidence of bilateral post-LASIK keratitis occurring out of 204,586 procedures. Investiga- tors pegged the most common causes of microbial post-LASIK keratitis as coming from atypical mycobacteria as well as Gram- positive infections. Francis S. Mah, M.D., co-medical director, Charles T. Campbell Ophthalmic Microbiol- ogy Laboratory, University of Pitts- burgh School of Medicine, thinks that the numbers here are in keep- ing with what could be expected. "As far as what their experiences were in bilateral infections and atypicals and so forth, it seems ap- propriately low," Dr. Mah said. "As we move forward from this data and from some of the epidemics of November 2011 issue of Clinical and Experimental Ophthalmology, investi- gators pulled charts of patients who had mycobacterial infections from 1980-2007. Many of these patients who were ultimately evaluated at Bascom Palmer were referred from other centers where they were being treated for presumptive bacterial in- fections, according to Dr. Girgis. All too often this is misdiag- nosed. "In patients that were re- ferred to us there was definitely a long time between when the patient started having the symptoms [and when] the presumptive diagnosis was made," Dr. Girgis said. Typically this was about 60 days. She thinks that part of the reason is that practi- tioners are not attuned to this. "I think a lot of times it's not on peo- ple's radars—it's not super com- mon," she said. "People are not necessarily attuned to thinking that this could be mycobacterial." Scouting risk factors Investigators found that biomateri- als were the strongest risk factor for infection. "We think that the my- cobacteria themselves are known to be able to form biofilms," Dr. Girgis said. "It's natural for them to be able to proliferate and grow in these biofilms when you have some kind of material inside of the eyes." Steroids were also found to be Microbial post-LASIK keratitis Source: Elizabeth A. Davis, M.D. atypicals, I think that their conclu- sion that most of the infections are atypical is probably a little over- stated based upon reporting biases." Dr. Mah worries that when ini- tially seeing something unusual, such as an atypical infection, this may tend to be reported more than the run-of-the-mill bacteria. His im- pression is that Staph infections are far more likely. "My gestalt, what I have been seeing, and what people have been reporting by word-of- mouth and at meetings, is that it's probably going to be the more com- mon causes of post-LASIK infection such as Staph aureus and Staph epider- midis that are the most common eti- ologic agent in that atypicals right now seem high because of reporting bias," he said. Still, he urges practitioners to keep such atypical infections in the back of their minds. "If you're not getting the response that you ex- pect, don't wait too long in considering some of the special techniques used to diagnose and treat some of the atypical agents," Dr. Mah said. Editors' note: Dr. Mah has no financial interests related to this article. Contact information Mah: 412-647-2211, mahfs@upmc.edu another common risk factor. "Any time we're suppressing the immune response with steroids, it makes things a little bit more difficult in terms of the bacteria that are caus- ing the infections," Dr. Girgis said. "So a lot of patients were coming in being treated with steroids with or without antibiotics or antivirals, and that seemed to be a real risk factor." In addition, undergoing any ocular surgery was also found to put pa- tients at risk. The prevalence of mycobacterial infections appears to be growing. "From 1980-1990, only 13% of eyes were infected versus from 2000-2007 [when] it rose to 56%," Dr. Girgis said. "Clearly surgeries are becoming more common, more biomaterials are being sent to the eye, perhaps [there is] resistance to common an- timicrobial agents—those are proba- bly all factors that have contributed to the rise of these infections." Charting the clinical course Unfortunately, when it comes to