Comparison of fungal fluorescent staining and ITS rDNA PCR‐based sequencing with conventional methods for the diagnosis of onychomycosis

Abstract

BackgroundThe current gold standard for diagnosing onychomycosis is direct microscopic examination and culturing. Fungal culture is a time‐consuming procedure, while direct microscopy of potassium hydroxide (KOH) mounts suffers from low sensitivity. More rapid and sensitive methods for the diagnosis of onychomycosis are in high demand.ObjectiveTo establish an effective method for the diagnosis of onychomycosis by assessing the efficacies of fungal fluorescent staining and internal transcribed spacer (ITS) ribosomal DNA (rDNA) polymerase chain reaction (PCR)‐based sequencing.MethodsA total of 204 clinical specimens from patients with suspected onychomycosis were analysed. The gold standard for a true positive sample was positive by KOH, culturing or both methods. All specimens were also tested by fungal fluorescent staining and ITS rDNA PCR‐based sequencing. We compared the detection, sensitivity and specificity for these two methods with conventional methods.ResultsIn total, 126 (62%) and 102 (50%) were detected by fluorescent staining and PCR‐based sequencing, respectively. According to the conventional diagnostic standard, the sensitivity of fluorescent staining and PCR‐based sequencing was 97% and 78%, respectively, and specificities of 89% and 90%, respectively. Use of fluorescence enhanced the sensitivity of direct examination by 12% compared with KOH. PCR‐based sequencing increased the sensitivity by 6% compared with culturing.ConclusionsFluorescence microscopy has a higher sensitivity for the detection of fungi in nail specimens compared with KOH and can be used as a rapid screening tool. PCR‐based sequencing was faster and more sensitive compared with culture and when used in conjunction with fluorescence microscopy resulted in higher efficiency.

Combined laser and ozone therapy for onychomycosis in an in vitro and ex vivo model

“…Another method is the PCR technique, which can determine the causal agent by amplification of 18S rRNA. All of these techniques are not 100% effective, so a combined use allows a better identification, decreasing false negatives [16][17][18].…”

Fusarium onychomycoses in Switzerland—A mycological and histopathological study

“…Non‐dermatophyte moulds cause about 10% of the onychomycoses with a range from 1.45% to 17.6% . Fusarium spp alone were estimated at 1%‐6% of onychomycoses, but were found in a higher percentage in other studies .…”

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

“…Regarding other methods, Lubis et al 20 and Bao et al 21 reported the use of DNA methods such as real-time PCR and restriction fragment length polymorphism to detect possible fungal infection, and to improve the reliability of questionable fungal test results based on current sensitivity and specificity data. Using DNA detection methods provided higher sensitivity and specificity, indicating that both could be improved.…”