To analyze the minimum inhibitory concentration (MIC) of isolates from fungal keratitis to natamycin and voriconazole, and to assess the relationship between organism, MIC, and clinical outcome.
Data were collected as part of a randomized, controlled, double-masked clinical trial. Main outcome measures included best spectacle-corrected visual acuity (BSCVA), infiltrate/scar size, time to re-epithelialization, and perforation. Speciation and analysis of MIC to natamycin and voriconazole was done according to NCCLS standards. The relationship between MIC and organism, organism and outcome measure, and each outcome measure and MIC was assessed.
Of 120 samples obtained in the trial, 84 isolates had an identifiable organism and were available for further analyses. Fusarium spp and Aspergillus spp were the most commonly-isolated organisms. MIC was significantly different across the groups of organisms (P=0.0001). A higher MIC was significantly associated with an increased likelihood of perforation (OR 2.03, 95%CI 1.02 to 4.04, P=0.04). There was no significant association between MIC and 3-week visual acuity (0.058, 95%CI -0.01 to 0.13, P=0.11), 3-month visual acuity (0.01, 95%CI -0.08 to 1.04, P=0.79), 3-week infiltrate/scar size (0.12, 95% CI -0.02 to 0.27, P=0.10), 3-month infiltrate/scar size (0.12, 95%CI -0.02 to 0.25, P=0.09), or time to re-epithelialization (HR 1.19, 95%CI 0.98 to 1.45, P=0.08).
A higher MIC was associated with an increased odds of perforation. The results of this study suggest that resistance to antifungal medication may be associated with worse outcomes in fungal keratitis.