Fighting ocular infections
New infection emerges

Investigators work to prevent spread of Fusarium keratitis

Fungal keratitis.
Source: Francis Mah, M.D.

Fusarium keratitis infections are quite uncommon in the United States because they thrive in tropical climates, but an April Centers for Disease Control and Prevention (CDC) report cited 109 cases under investigation in 17 states.
In fact, clusters of Fusarium keratitis have become something of a worldwide problem, having also surfaced in Asia beginning in February.
As a preventative measure, Bausch & Lomb (Rochester, N.Y.) voluntarily suspended sales of its ReNu with MoistureLoc contact lens solution in Asia as well as in the United States and ran full-page ads to educate Bausch & Lomb customers on how to keep their eyes safe.
In a preliminary analysis of the U.S. cases in which complete data were obtained for 30 eyes, 26 reported using a Bausch & Lomb ReNu brand solution in the month prior to onset of infection. An investigation is ongoing to determine whether there was a cause-and-effect relationship between the solution and the infections.
While Bausch & Lomb arguably took aggressive measures to educate patients about preventing Fusarium keratitis infection, more detailed advice on preventing and treating Fusarium keratitis also could be useful for the ophthalmic community.
EyeWorld asked researchers and physicians familiar with Fusarium keratitis how best to catch this vision-threatening infection and what to do when they see it.

Separating fungal from bacterial infections

“In general, we almost never see Fusarium keratitis,” said Francis S. Mah, M.D., co-medical director, Charles T. Campbell Ophthalmic Microbiology Laboratory, University of Pittsburgh School of Medicine. “We'll usually see one or two a year in the Pittsburgh area.”
But Mah said his clinic recently saw 12 cases in a six-month period, about which he has since been in contact with the CDC.
Despite the recent rash of cases, Dr. Mah said one of the most important things that U.S. ophthalmologists should keep in mind about eye infections is that bacterial corneal infections are still more common.
“Don't immediately think fungus and ignore bacteria,” Dr. Mah said, “but we do need a high index of suspicion since patients do better when identified earlier.”
H. Dwight Cavanaugh, M.D., Ph.D., professor of ophthalmology, University of Texas Southwestern Medical Center, Dallas, agreed.
“The fungus infections are so rare with contact lenses,” Dr. Cavanaugh said. “It's like buying a lottery ticket at 7-Eleven and winning. This is a real problem but is a rare problem.”
Christopher J. Rapuano, M.D., professor of ophthalmology, Jefferson Medical College of Thomas Jefferson University, and co-director, Wills Eye Hospital, Philadelphia, said it is important to have a greater degree of suspicion that corneal infections could be fungal in light of the recent outbreaks but most important is obtaining proper cultures to determine the cause of the infection.
“Many times cultures aren't obtained,” Dr. Rapuano said. “You need to get cultures to make a definitive diagnosis of Fusarium.”
That's because many people with such infections may not have the classic appearance or history that goes along with that type of infection, he said.
“Let's say you treat an infection with antibiotics and it's not getting better after five days,” Dr. Rapuano said. “Then you really have to suspect it's not bacterial and it may be fungal. Now you have to get a scraping.”
Then, he said, if the scraping for fungus turns out to be negative but the antibiotics still aren't working, you should seriously consider doing a corneal biopsy to make a proper diagnosis, Dr. Rapuano said.
Signs of a fungal infection that can be seen, however, might include satellite lesions in different spots around the cornea, along with feathery margins to the infiltrate, Dr. Mah said. If the infection looks very deep with a lot of inflammation, this also could be a fungus, he said.

Optimal Fusarium treatment

If an ophthalmologist confirms that a patient indeed has a Fusarium keratitis infection, the recommended medication should be natamycin (Natacyn, Alcon, Fort Worth, Texas), which is the only commercially available topical anti-fungal medication, Dr. Rapuano said
“Use it every 30 to every 60 minutes around the clock,” Dr. Rapuano said. “It's an intensive treatment for a few days.”
If a patient does not get significantly better, ophthalmologists should consider systemic anti-fungal medication in the form of pills.
Dr. Mah agreed that natamycin is an effective treatment, but he said it can be difficult to obtain from pharmacies right away because it is expensive and rarely ordered.
“There have also been reports that voriconazole (Vfend, Pfizer, New York), has excellent activity against Fusarium,” Dr. Mah said. He also said he has used natamycin along with topical amphotericin B (Bristol-Myers Squibb, New York). Oral fluconazole (Diflucan, Pfizer) also is an option, he said.
But Dr. Mah said the problem is fungi are slower growing and more difficult to kill than bacteria. In general, there is more drug resistance associated with them, they cause more inflammation, and Fusarium keratitis usually progresses and penetrates deeper into the stroma, he said.
“Fusarium will spread deeper rather than wider,” Dr. Mah said. “Frequently the fungal infection will go all the way down to Descemet's and even into the anterior chamber, even in relatively small corneal fungal keratitis.”
In fact, some fungal infections may not respond to medical treatment, and the patient may need an urgent corneal transplant, Dr. Rapuano said.
“A fungus is one of the most horrible infectious organisms around,” Dr. Cavanaugh said.
Fortunately, because so much awareness and so many precautions have been taken against further Fusarium keratitis infections, if patients have not been affected by the recent cluster by now, they basically are not going to be affected, said Dr. Cavanaugh.
While there was a flurry of case reports in April, the reports seem to have tapered off, said Dr. Cavanaugh, one of the principle regional investigators of the outbreaks for the CDC and Food and Drug Administration (FDA).
“I haven't heard of any new reports this week [or] last week,” Dr. Cavanaugh said. “There is certainly not an epidemic of blindness.”

Editors' note: Dr. Mah is a consultant for Allergan (Irvine, Calif.) and Alcon (Ft. Worth, Texas). Dr. Rapuano lectures for Allergan and Alcon. Dr. Cavanaugh has no financial interests related to his comments.

Contact Information
Cavanaugh: 214-648-8074, dwight.cavanaugh@utsouthwestern.edu
Mah: 412-647-2214, Mahfs@upmc.edu
Rapuano: 215-928-3180, cjrapuano@willseye.org