Evaluation Of Confocal Microscopy And Etest In Diagnosis And Prognosis Of Fungal Keratitis

PurposerTo evaluate the role of confocal microscopy in early diagnosis and progression of varied fungal keratitis and fungal susceptibility testing in prognosis of keratomycosis.Subjects and methods:AH patients clinically diagnosed as fungal keratitis between Nov 2002 and Mar 2003 were included in this study.Enrolled patients were initially examined by slit lamp microscope,then followed by confocal microscopy,corneal scraping for culture,slide culture and Etest.Once fungal keratitis be suspected,Oral itraconazole 300mg daily was immediately initiated until results of fungal susceptibility testing were available.Patients would receive additional 0.15% amphotericin B eye drop every ten munites when fungal susceptibility testing revealed pathogen were susceptible to amphotericin B.Each patient routinely received 3% ofloxacin eye drops four times daily to prevent bacterial infection.During systemic administration of antifungal agents,the levels of hepatic enzymes were monitored every 2 weeks.If there was a rise of hepatic enzymes,the systemic drugs were tapped or withdrawn.Otherwise,these drugs were tapered according to the regression of conjuntival hyperemia,corneal infiltration and inflammatory reaction in the anterior chamber.After complete resolution of inflammatory reaction,oral itraconazole 100 mg daily was still continued for one more month.Surgical intervention with thrapeutic penetrating keratoplasty is indicated when fungal keratits progressed to anterior chamber collapse,corneal perforation,and/or large suppurativc corneal infiltrate(larger than 8mm).One case received Full-bed deep lamellar keratoplasty as hyphae didn't penetrate Descemet's membrane.Results:The fungus was grown in cultures and identified as Fusarium solani in 12 cases,Fusarium oxyporium in 3 cases, Curvularia gericulate in 1 case, Aremonium sp.in 1 case,Aspergillus flavus in 1 case and Pseudosporium apiospernum in 1 case.Obvious hyphae were found in confocal microscopy of 19 cases(76.0%).Of them, 15 cases(100%) are Fusarium sp,1 case is Aremonium sp., 1 case is Aspergillus flavus, 1 case is Pseudosporium apiospernum and 1 case has unkown pathogen.There are 5 cases who healed after antifugal therapy while both culture and confocal microscopy showed negative.Each fungal species has its morphological characteristics in confocal microscopy. Highly luminant filamentous structures were observed intrastromally in Fusarium solani.The hypha is about 5 um in width with intercrossed angle about 45 degree.The hyphae of Fusarium oxyporium clstered with angle less than 45 degree. Aremonium sp.has a wider hyphae than Fusarium sp. There are shorter hyphae and less branches in Aspergillus flavws.Straighter and darker hyphae can be observed in Pseudosporium apiospernum.ln addtion,confocal microscopy is helpful in evaluating the progression of fungal keratitis.In early stage of keratomycosis, fungal filaments are dominant with few inflammatory cells.When the treatment showed effective,the amount of fungal filaments declined while inflammatory cells increased.In the late stage of the treatment,we observed more inflammtory cell infiltration without obvious hyphae in confocal microscopy.Amphotericin B is active against the majority of Fusarium sp.(75%).None of the Fusarium sp is sensitive to fluconazole and itraconazole. Curvularia gericulate and Aspergillus flavus correspond susceptibility to all of three antifungal drugs.On the contrary, Aremonium sp and Pseudosporium apiospernum are resistant to all.Ten cases of twenty-five received threapeutic penetrating keratoplasty.One case receive full-bed deep lamellar keratoplasty.Conclusion:Confocal microscopy provided useful tool to make early diagnosis and monitor the progression of fungal keratitis.New antifungal susceptibility test,Etest,play a important role in evaluating the efficiency of antifungal therapy.