Culture Results May Guide Treatment of Severe Fungal Keratitis
American Journal of Ophthalmology, May 2018
In a secondary analysis of data from the Mycotic Ulcer Treatment Trial–II (MUTT–II), Ray et al. aimed to identify patients with fungal keratitis who are at risk of poor outcomes and thus may benefit from aggressive treatment and additional monitoring. They found that patients with positive (vs. negative) cultures on day 6 had a 2-fold greater risk for corneal perforation or the need for therapeutic penetrating keratoplasty (PK).
For this secondary analysis, the researchers included patients with smear-positive filamentous fungal ulcer and visual acuity (VA) of 20/400 or worse at presentation, at which time medical therapy was started. Using backward stepwise regression with covariates for baseline traits, the authors compared clinical outcomes between patients who had positive cultures and those who had negative cultures on day 6. The primary outcome measure was the rate of corneal perforation and/or need for therapeutic PK. Secondary outcomes included 3-month best spectacle-corrected VA (BSCVA), size of infiltrate/scar at 3 months, and rate of re-epithelialization.
The analyses showed that, even after controlling for baseline ulcer characteristics, patients with positive cultures on day 6 had twice the hazard of experiencing corneal perforation or needing therapeutic penetrating keratoplasty (p = .002) than patients with negative cultures. Moreover, culture positivity correlated with poorer BSCVA at 3 months (average of 0.26 logMAR lines worse than for patients with negative cultures; p = .001). However, a positive culture on day 6 was not predictive of infiltrate/scar size or the time to re-epithelialization.
Hence, 6-day culture results may be a valuable tool for making treatment decisions for patients with severe fungal keratitis. Findings of repeat cultures may be useful for risk stratification and for identifying patients at high risk of poor outcomes. Culture positivity is an objective indicator of response to medical therapy. The authors stated that this research, coupled with their earlier findings for less severe ulcers, represents the advent of a new standard of care for fungal keratitis.
The original article can be found here.