Comparison of fluorescent staining and KOH wet-mount microscopy in the diagnosis of different type of tinea pedis

Abstract

Objective: To compare the positive rate and average time for slide reading of fluorescent staining versus KOH wet-mount microscopy in the diagnosis of different types of tinea pedis. Methods: Specimens were collected from 118 cases of blister scaly type tinea pedis, 104 cases of cornification excess type tinea pedis and 78 cases of soak erosion type tinea pedis. These specimens were subjected to fluorescent staining and KOH wet mount separately, followed by KOH wet-mount microscopy. The positive rate and average time for slide reading were compared between the two methods. Results: The background of fluorescent staining method was relatively clean, and the fungi was clearly identifiable, while the background of KOH wet-mount method was messy and it was difficult to identify fungi. In three different types of tinea pedis, the positive rates were 91.53%, 75.96% and 98.72%, respectively using fluorescent staining method, while the positive rates were 80.51%, 47.12% and 97.44%, respectively when KOH wet mount was used. The positive rates for blister scaly type tinea pedis and cornification excess type tinea pedis were significantly different between the two methods(χ2=5.33, 20.45 respectively, both P<0.05). In 118 cases of blister scaly type tinea pedis, fluorescent staining took shorter reading time than KOH wet mount[(65.23±10.60) s vs. (90.75±12.15) s, t=13.51, P<0.05). Likewise, in 104 cases of cornification excess type tinea pedis, the time to read fluorescent staining as also shorter than KOH wet mount [(90.52±13.23) s vs. (150.35±15.16) s, t=15.60, P<0.05). Moreover, in 78 cases of soak erosion type tinea pedis, the reading time of fluorescent staining was shorter than KOH wet mount [(38.13±8.62) s vs.(48.28±16.20) s, t=18.35, P<0.05). Thus, average reading time was shorter with fluorescent staining than KOH wet-mount microscopy in all three different types of tinea pedis. Conclusion: In the diagnosis of tinea pedis, compared with KOH wet-mount microscopy, fluorescent staining increases the detection rate, lowers missed diagnosis rate and shortens reading time.

Keywords

• tinea pedis
• fungus
• fluorescent staining
• koh wet-mount method