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R. A. Oechsler, M. Feilmeier, D. L. Ledee, D. Miller, M. Diaz, M. E. Fini, J. Fell, E. C. Alfonso; Genotypic Identification of Fusarium sp From Ocular Sources and Correlation to Clinical Outcomes in South Florida. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2495. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Fungal keratitis is a prevalent cause of ocular morbidity throughout the world. Fusarium, a genus of filamentous fungi, is the most frequent corneal fungal pathogen in subtropical and tropical regions, however traditional identification methods have yielded discordant species concepts. In this study we utilize sequence genotyping to confirm and classify the documented cases from southern Florida, and explore the possible correlation between genotype and disease phenotype and clinical outcome.
Sequence for the nuclear internal transcribed spacer (ITS) region of 58 ocular Fusarium sp isolates was determined (41 corneas, 4 aqueus humor, 1 vitreous, 8 contact lenses and 4 contact lens cases)and relatedness assessed by phylogenetic analysis. According to the morphological classification, the isolates were divided into Fusarium oxysporum= 19 (33%), F. solani= 11 (19%) and F. sp= 28 (48%) isolates. Clinical outcomes were assessed by a retrospective review of 38 available medical records of the source patients with ocular Fusarium sp infections between May 2000 and April 2007.
Phylogenetic analysis placed the 58 isolates into 4 species complexes: Fusarium solani species complex (FSSC)= 76% and Fusarium non-solani species complexes (FNSSC)= 24% (Fusarium oxysporum species complex (FOSC)=16%, Fusarium incarnatum-equiseti species complex (FEISC)=5% and Fusarium dimerum species complex (FDSC)=3%).The mean age of the patients was 39.6 years (54% female; 46% male). Mean follow up time was 7.5 months. Time to resolution was on average 69 days for isolates in the FSSC compared to 46 days for the FNSSC. Central ulcers were present in 21% of the FSSC and in 22% of the FNSSC. Mean final visual acuity was 0.65 LogMAR (+/-20/90) in the FSSC and 0.31 LogMAR (+/-20/40) for the FNSSC.
Genotyping confirmed the inconsistency of identifying fungal isolates utilizing traditional methods and offers a rapid method to analyze clinical samples. Correlation of the genotypes with clinical outcomes established that final visual acuity and time to resolution tended to be significantly worse in the FSSC than in the FNSSC.
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