The big chill: Icing saline leads to LASIK infections
Pathogen source found in drain of ice machine
The apparently common practice of chilling saline solution in ice during LASIK eye surgery may lead to corneal infections in patients, researchers warn. Eye infections in five patients were traced to an ice machine that was serving as a reservoir for the infecting pathogen: Mycobacterium szulgai, says Gregory Bond, RN, nurse epidemiologist at Scott & White Memorial Hospital and Clinic in Temple, TX. This appears to be the first investigation of an infection cluster following laser-assisted in situ keratomileusis (LASIK), and the first to link M. szulgai infection with an environmental source, Bond and colleagues report.1
After reviewing the surgeon’s practice of icing the saline eye-irrigating solution, they compared the infecting pathogen with isolates taken from a nearby ice machine. A culture from the drain of the ice machine grew M. szulgai, which matched the outbreak strain by pulsed-field gel electrophoresis. "It was a carbon copy," Bond tells Hospital Infection Control.
A commonly performed procedure to correct myopia, hyperopia, and astigmatism, LASIK was added to the institution’s surgical offerings in June 2000. However, in October of that year, the first infected patient was discovered. Investigators did a retrospective cohort study of all LASIK procedures between June 6 and Oct. 24, 2000, with follow-up through March 31, 2001. They found that five of 52 patients (9.6%) had confirmed postoperative M. szulgai keratitis. All five cases were identified among 18 patients (30 procedures) of "Dr. A." No infections were found among 34 patients (62 procedures) treated by "Dr. B."
"It took a while for the [infections] to appear, and the patients did not have optimal postoperative courses," Bond says. "They began to develop infection problems that did not respond to the usual treatment. As these [infections] went on and on, one surgeon decided to do a scraping and sent it for acid-fast studies. That is when it showed up that it was an acid-fast organism."
With M. szulgai identified, appropriate antibiotics could be targeted at the pathogen and all patients recovered. "They all resolved eventually," Bond says. "Some were very slow to recover because of the difficulty in treating that type infection."
Two other patients of Dr. A had similar corneal lesions that were not cultured, but were treated as probable cases. The surgeon’s techniques differed only in his use of saline lavage that was chilled in a tub of ice. The other surgeon used saline directly from its stock bottle without chilling it. "It’s a rinse solution used as they are doing those procedures," Bond explains. "It was brought up into a syringe with an irrigating-type tip. [Dr. A and staff] would draw up the solution and place it on a bed of ice just to chill the solution."
Though the medical benefit is unclear, the surgeon reported being taught to chill the solution when working at another hospital that did numerous LASIK procedures. There were no reported problems at the other institution, Bond says. "This particular surgeon learned his technique in a large practice there, and that was the process that they used. I never really saw an explanation for the benefits or exactly why they were chilling the saline. He was just following the practice he had been taught. It seems to be a fairly common practice," he explains.
Transmission to the patients’ eyes apparently occurred by the syringe tip becoming contaminated by the ice or possibly on the hands of a health care worker who handled both the ice and syringe. "We don’t know the exact process for inoculation, but it is linked back to the ice and to the water source," Bond says. "People just need to be aware that water sources, regardless of how potable the water is, are still going to have some type of organisms in them. Mycobacteria may be one of those that is either in the water system itself or in draining systems."
While using an unchilled solution is an obvious intervention, medical practitioners who favor the chilling technique should take some additional measures, he advises. They could chill the container of solution and then draw it into the syringe, he notes. "[Do] something so the syringe and tip are not in such close proximity to the ice," he says. "They could put a sterile plastic sheet or something over the ice to maintain the sterility of the field."
The surgeon decided to discontinue LASIK procedures and do other types of eye surgery. "I think that once the source was found, he wouldn’t have had any additional problems with it," Bond says. "But that was his choice."
(Editor’s note: We are trying to find out more about the practice described in this article. If your facility does LASIK procedures, is the saline solution chilled on ice? Have you had any problems with the practice? Please go to the forum section of your free subscriber web site at www.HIConline.com and post a note regarding this. Information shared in the forum is for HIC subscribers only and is not published in the newsletter. Thanks for your input.)
Reference
1. Holmes GP, Bond GB, Fader R, et al. A chilling experience: A cluster of Mycobacterium szulgai keratitis following laser assisted in situ keratomileusis (LASIK) Abstract 478. Presented at the 41st Interscience Conference on Antimicrobial Agents and Chemotherapy. Chicago; December 2001.
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