Coexistence of Fungal Infections in Psoriatic Nails and their Correlation with Severity of Nail Psoriasis

BACKGROUND: Nail involvement in psoriasis is often complicated by concomitant fungal infections. The aim of this study was to investigate the prevalence of fungal infections in nail psoriasis and correlate it with the severity of nail psoriasis. MATERIALS AND METHODS: This retrospective study included patients with nail psoriasis aged ≥18 years with at least one fingernail and one toenail involvement who were treated at Siriraj Hospital from September 2012 to January 2014. Severity of nail psoriasis was assesed by Nail Psoriasis Area Severity Index (NAPSI) score. The nail clippings from the the least and most severely involved psoriatic fingernails and toenails were cultured to determine the presence of coexisting fungal infections and isolate the fungal species. RESULTS: Sixty-two patients (33 males, 29 females) fulfilling the inclusion criteria were included in the study. The mean age at the time of presentation was 51.3 years mention SD. The most common nail change consistent with psoriasis was onycholysis, followed by subungual hyperkeratosis. The most commonly isolated fungi in the most severely affected fingernails were Candida spp. (41.9%) manifesting as paronychia in 5 patients (19.2%). The most commonly isolated fungi in the most severely affected toenails were nondermatophytes (NDMs) other than candida (32.3%). Dermatophytes were not detected from any of the psoriatic nails. The fungal species isolated from the most severely affected fingernails were significantly different than the isolated fungal species in the most severely affected toenails (P = 0.026). Fungal organisms were identified in 32.3% of the most severely affected fingernails and in 27.4% of the most severely affected toenails. The overall rate of isolation of fungus was significantly significantly higher in severely affected nails than in the least affected nails (P < 0.005). CONCLUSION: A high rate of concomitant fungal infections, especially yeasts and NDMs, was found in psoriatic nail patients. The rate of isolation of fungal species was higher in severely involved psoriatic nails than mildly involved ones. The spectrum of fungal species isolated from the the severely involved toenails and fingernails were also different from each other. These organisms may be true pathogens that cause onychomycosis or their presence may reflect colonization, contamination, or concurrent infection.