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R. A. Oechsler, M. R. Feilmeier, D. Miller, E. C. Alfonso; Differences in Clinical Outcomes and Antifungal Susceptibility Among Fusarium Species From Ocular Isolates. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2401.
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To examine the differences in clinical outcome and antifungal susceptibility among the different species of Fusarium causing keratitis.
Fifty eight Fusarium isolates obtained from ocular sources were grown in pure culture. DNA was extracted and purified from each isolate and a region containing the ITS1/2 and rDNA was amplified using selected primers. These regions were genotyped and the sequences compared with reference strains in GenBank. Antifungal susceptibilities were determined for each of the isolates using broth microdilution methods. Finally, the corresponding medical records from the 50 patients were reviewed. The main clinical outcome measures were the final visual acuity, time to cure and need of urgent surgical procedures among different genotypes.
The genotypes found belonged 75% to the Fusarium solani species complex and 25% to Fusarium non-solani species complexes. Fusarium isolates in general showed high levels of resistance to the antifungal agents tested. F. non-solani isolates were more susceptible to voriconazole compared to the F. solani isolates (MIC90= 4ug/ml vs 16ug/ml, p<0.05). F. solani infections exhibited a significantly longer time to cure (57days vs 43 days, p<0.01) and worse final visual acuity (20/80 vs 20/35, p<0.01) compared to F. non-solani. In addition, all urgent corneal transplant surgeries were performed in the F. solani group.
In this study, F. solani ocularisolatesappear to be more pathogenic than F. non-solani isolates and were associated with higher levels of resistance to a triazole. The differences in antifungal susceptibility and clinical outcomes when comparing F. solani and F. non-solani, support the use of genotyping classification systems, which are capable of reliable identification of organisms to the species level. Additionally, these findings suggest that such classification systems may yield important prognostic and therapeutic information that could redefine the future management of fungal ocular infections.
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