Pathogenic spectrum of fungal keratitis and specific identification of Fusarium solani.

PURPOSE To investigate the predominant causative pathogens and epidemiologic features of fungal keratitis and establish a rapid, specific molecular method to detect fungal keratitis caused by Fusarium solani. METHODS A total of 174 patients with presumed fungal keratitis and 174 affected eyes were examined. Isolates from corneal specimens were identified according to morphologic and physiological characteristics. The primers that were designed for F. solani were tested to confirm whether they had species specificity. Multiplex PCR with universal fungal and F. solani-specific primers was performed with fungal and bacterial strains and was used to detect microorganisms in the clinical specimens. RESULTS A total of 160 patients (92.0%) were diagnosed with fungal infection by either potassium hydroxide wet-mount or microbiologic culture. Fungal cultures were positive in 128 patients (73.6%) with 139 fungal isolates. Fusarium (48.2%) was the most frequently isolated genus, in which F. solani (35.2%) was the most common species, followed by the Aspergillus (18.7%) and Candida (16.6%) genera. The PCR results showed that the designed primers were species specific and suitable for specific identification of F. solani. The multiplex PCR of 3-day broth cultures could identify and distinguish F. solani from other pathogens rapidly and specifically from clinical specimens. CONCLUSIONS Fusarium species, especially F. solani, were found to be the predominant cause of fungal keratitis in northeast China. The established multiplex PCR method could have potential advantages for rapid detection of F. solani. These findings might have significance for early diagnosis and treatment of fungal keratitis.