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Rare fungal pathogen in PRK patient baffles doctors
Two unusual cases of infective keratitis after PRK reaffirm the need for vigorous postop care and adherence to sterile techniques.
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DENVER — Ophthalmologists here were stumped by an unusual case of fungal infection in a photorefractive keratectomy (PRK) patient referred to their center for an eye infection. The patient eventually underwent penetrating keratoplasty (PK). The source of the infection was never determined.
Gregory Kouyoumdjian, MD, and colleagues reported on their experience treating two cases of unusual corneal infection after refractive surgery in a recent issue of Ophthalmology.
The fungal strain Scopulariopsis that infected the eye of a 36-year-old man after PRK may have resulted from hygienic factors. Dr. Kouyoumdjian said they searched extensively to find the source of infection.
“This fungus, especially here in Denver, is extremely rare. It might have had something more to do with this person’s hygiene than anything that the surgeon inoculated in this person’s eye,” he said.
Everything cultured
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“This person lived on a boat on a lake in the mountains. He was also a heavy marijuana user and grew marijuana plants. We cultured everything: the seats on his boat, his toenails and fingernails. Finally, we even cultured his marijuana plants and soil, trying to find the source,” Dr. Kouyoumdjian said.
The cultures were negative, even the toenails, the most likely location of this particular fungus. They tested the seats of the boat after the patient described them as being moldy.
“So we told him to bring in a sample of the mold, using as much of a sterile technique as possible, just so we could grow the mold. We wanted to find where this fungus came from. From all the research I’ve done, his toenails were still the most likely source. Maybe he was touching his toes before he instilled the next drop and maybe accidentally touched the eye with his finger,” he said.
In his tertiary care center, Dr. Kouyoumdjian said it is uncommon to see more than one case per year of fungal keratitis, which is usually Candida — usually a contact lens fungal keratitis.
“This was remarkably rare and very tough to figure out,” he said.
At the time of presentation to his center, 3 weeks after PRK, vision was already hand motion, and a large central ulcer and plaque were apparent. Despite aggressive antifungal medical therapy, the infection persisted. Anti-infectives included clotrimazole, cefazolin, ketoconazole and natomycin.
PK was then performed, with 8 mm of the host cornea requiring excision. Histology on the ulcerated cornea was positive for mycotic keratitis.
In cases of any sign of corneal infection after refractive surgery, obtaining a culture at the earliest possible time can be critically important. Too much time went by before the correct diagnosis of a fungal pathogen was made in this case. A fungus infection after PRK is relatively easier to treat compared with LASIK, Dr. Kouyoumdjian said.
“When you’ve got something that looks suspicious after refractive surgery, you have to culture early,” he said. “That’s much easier to treat than when the flap interface is just getting ravaged by these bacteria; that’s what we were noticing. You can’t just culture the surface of the eye; you have to lift the flap and scrape away the infiltrates. That’s the best way to treat herpetic keratitis, for example. You scrape away the lesion and then start your treatment. And likewise for any flap interface infections; you really need to lift the flap and be aggressive with anything that looks like infiltrate.”
Four months after PK, the patient demonstrated 20/20 acuity while wearing a rigid gas-permeable contact lens.
Only three cases of Scopulariopsis fungal keratitis have been reported in the medical literature, and no cases following refractive surgery have previously been reported, Dr. Kouyoumdjian and colleagues noted.
Sterility compromised
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In another referral to the same center, a 31-year-old woman presented with 20/200 uncorrected vision 7 weeks after an uncomplicated LASIK. Prior to referral there had been two flap liftings and irrigation due to an “inflammation or infection of unknown cause.”
Upon examination, Dr. Kouyoumdjian noted stromal-interface granularity. The flap was lifted and irrigated with antibiotics and saline. Cultures were obtained, which identified the pathogen as Mycobacterium chellonae. After showing no improvement on medical therapy, which included clarithromycin and sulfacetamide, PK was performed. Histology of the excised corneal button confirmed Mycobacterium keratitis.
“On that day, the surgeon had seven cases of 14 refractive surgery patients that ended up with M. chellonae, so probably the sterilization water was not adequate, or worse yet that’s where the Mycobacterium was growing. Close examination of the corneal button revealed a tract infection, suggesting contamination of the microkeratome with Mycobacterium,” he said.
Only two cases of M. chellonae keratitis after refractive surgery had been previously reported.
The patient had a clear corneal graft 4 months after surgery with 20/70 uncorrected vision.
In the two patients he treated, visual outcomes are expected to be consistent with the prognosis for any PK.
“Since they didn’t suffer any endophthalmitis and nothing penetrated the inner part of the eye, they will do as well as anyone receiving a PK,” he said.
These two cases, though extremely rare, point out the potential for infection and “the need for strict adherence to sterile techniques. They also reaffirm the need to reassess a refractory corneal ulcer with smears and cultures and thorough post-laser refractive surgery care,” the authors concluded.
For Your Information:
- Gregory Kouyoumdjian, MD, can be reached at Corneal Consultants of Colorado, 8381 Southpark Lane, Littleton, CO 80262; (303) 730-0404; fax: (303) 730-6163.
Reference:
- Kouyoumdjian G, Forstat S, et al. Infectious keratitis after laser refractive surgery. Ophthalmology. 2001;108:1266-1268.