Liquid chromatography–tandem mass spectrometry is effective for analysis of ergosterol in fungal‐infected nails

Abstract

Summary Background Identification of onychomycosis is mainly based on clinical diagnosis with auxiliary diagnostic methods such as potassium hydroxide (KOH) microscopy, periodic acid–Schiff staining or fungal culture. However, each method is limited by its sensitivity and specificity. Aim To develop a new test method using the common fungal end product, ergosterol, and investigate if it can be used as a new diagnostic tool. Methods We collected consecutive data from 20 participants with nail problems. Following clinical diagnosis, samples were taken for KOH microscopy and for mass spectrometry (MS) to check for the presence of ergosterol. Results Of the 20 cases collected, 7 were positive for fungal infection by MS. Four of these were already suspected to have onychomycosis, whereas one of the remaining three subjects was presumed to have dry nail and the other two to have onycholysis. The MS test seemed to be better at detecting combinations of nail conditions. Conversely, of the five patients clinically diagnosed as having onychomycosis, four had a positive MS result, whereas the fifth had negative results on both KOH and MS. Two other participants had a positive KOH test and were also found to have positive MS results. Conclusion Detection of the presence of ergosterol by MS seems to be a useful tool for confirming onychomycosis. However, further studies are needed to verify the sensitivity and specificity of this MS method.