Clinical and laboratory characteristics of onychomycosis in patients with diabetes mellitus

Background. Onychomycosis is significant in patients with diabetes mellitus (DM), but its diagnosis is complicated due to its clinical resemblance to onychodystrophies. Objective. To evaluate the potential of PCR testing for the diagnosis of onychomycosis in patients with DM. Material and methods. The study included 46 patients: 17 (37.0%) men, 29 (63.0%) women; age 66.5 [54.5; 71.0] years. The patients were evaluated for nail changes (SCIO index), skin condition of the feet, and nail scraping results from KOH microscopy and PCR for Microsporum canis, Microsporum gypseum, Trichophyton spp., Epidermophyton floccosum, Trichophyton rubrum, Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, Aspergillus terreus, and Candida albicans. Results. Changes in nails were recorded in 26 (56.5%) patients, and in the foot skin in 29 (63.0%) subjects, 26 of whom presented with plantar scaling. In case of nail changes, the SCIO scores were distributed as follows: 16—30 points in 10 patients, 6—10 points in 8, 2—5 points in 5, and 11—15 points in 3. Onychomycosis was detected in 18 (39.1%) patients, a positive KOH microscopy result was obtained in 16 cases, and PCR was identified in 10 patients (DNA of Trichophyton spp. — 7 cases, Trichophyton rubrum — 4, Candida albicans — 3, Aspergillus niger — 1). All patients with positive PCR results were aged over 60 years, had type 2 DM and presented with foot skin changes. Conclusion. In DM, nail changes were more common (56.5% of patients) than onychomycosis (39.1%). Pathogenic fungi were detected by PCR in 21.7% of cases, increasing microscopy results by 10%. This demonstrates both the feasibility of PCR and the need to expand PCR diagnostic panels, given that the pathogen could not be identified by PCR in 8 out of 16 microscopy-positive patients.