Dermatophytosis: fluorostaining enhances speed and sensitivity in direct microscopy of skin, nail and hair specimens from dermatology outpatients

摘要

Direct microscopy of keratinised specimens is a standard screening procedure that assists clinicians to differentiate true superficial mycoses from non-fungal disorders of the skin, nail and hair. Most clinical dermatologists use bright-field microscopy when searching for dermatophyte fungi in clinical samples while laboratory-based mycologists increasingly favour fluorescence microscopy in order to optimise visualisation of fungal elements. This study compared the validity and speediness of fluorescence microscopy vs. conventional light microscopy when screening for fungi in 206 dermatological samples from dermatology outpatients. Both senior dermatologist and a less experienced investigator (medical student) attained high and comparable levels of specificity (91.7-93.8%), positive predictive value (77.1-81.4%) and negative predictive value (83.7-89.9%) using either method. Fluorostaining with Blankophor prior to fluorescence microscopy increased the sensitivity by 22 +/- 1% as compared to light microscopy of unstained samples. For both investigators, the time required to identify fungal elements by the fluorescence-based technique was reduced by at least 50%, thus improving the performance of direct microscopy in the clinical setting.