Growth Patterns Of Commonly Encountered Pathogenic Fungi In Experimental Keratitis

[Abstract] Purpose. To study the growth patterns and histopathological features of three commonly encountered pathogenic fungi in cornea in both models of contact lens-facilitated and epikeratophakia-induced keratitis of rabbits. Methods. 64 eyes in 64 New Zealand white rabbits were used in this study and randomized into 4 groups, including 1 control group. Three pathogenic fungi: Fusarium solani, Aspergillus fumigatus, and Candida albicans were examined. 0.1 ml of 3×10~9 CFU/ml of standardized inocula were placed on the debrided comeal surface of one eye in New Zealand white rabbits and covered with a contact lens or a full-thickness corneal graft sutured to the limbus of the recipient. 48 hours later, a temporary tarsorrhaphy was opened with removal of the contact lens or the grafts were removed. The infected corneas were photographed and examined daily with slit lamp biomicroscopy for fungal keratitis, and the uninfected animals were excluded. 6 rabbits from each group were randomly selected and sacrificed on day 3 and 8 after inoculation respectively. Corneas were sected for four parts for histopathological studies to investigate the growth patterns of fungi, in addition, corneas with features typical of fungal keratitis were examined with transmission electron microscopy. Results. The clinical features were different between three fungal keratitis of rabbits (P<0.05). The growth patterns of Aspergillus fumigatus, Candida albican and Fusarium solani were significantly different in the rabbit cornea(P<0.01). The ultrastructure features of the corneal stromal pathological change caused by three fungi were different. Conclusion. Three commonly encountered pathogenic fungi have different clinical symptoms, growth patterns in the rabbit cornea. The hyphae of A. fumigatus and C. albican traversed the cornea in a plane perpendicular to the stromal lamellae, while the hyphae of F. solani lay parallel to the corneal lamellae. It is difficult to establish the model of F. solani. keratitis and the infection was superficial.