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. 2014 Mar-Apr;18(2):181-6.
doi: 10.1016/j.bjid.2013.08.005. Epub 2013 Nov 22.

Microsporum spp. onychomycosis: disease presentation, risk factors and treatment responses in an urban population

Erick Martínez  1 , Mahreen Ameen  2 , Diana Tejada  3 , Roberto Arenas  4
Affiliations

Microsporum spp. onychomycosis: disease presentation, risk factors and treatment responses in an urban population

Erick Martínez et al. Braz J Infect Dis. 2014 Mar-Apr.

Abstract

Background: Dermatophytes are the main causative agent of all onychomycosis, but genus Microsporum is infrequent and the risk of acquiring the infection is often associated with exposure to risk factors.

Objectives: To describe clinical characteristics of onychomycosis due to Microsporum onychomycosis in an urban population.

Methods: This was a retrospective analysis of the epidemiological and clinical features of 18 Microsporum onychomycosis cases of a total of 4220 of onychomycosis cases diagnosed between May 2008 and September 2011 at the tertiary referral center for mycology in Guatemala.

Results: Eighteen cases of Microsporum onychomycosis (M. canis, n=10; M. gypseum, n=7; M. nanum, n=1) were identified (prevalence=0.43%). Infection was limited to nails only and disease duration ranged from 1 month to 20 years (mean=6.55 years). The toenails were affected in all cases except for a single M. gypseum case of fingernail. The most common clinical presentation was distal lateral subungual onychomycosis (12/18) followed by total dystrophic onychomycosis (5/18), and superficial white onychomycosis (1/18). M. gypseum presented in 6 cases as distal lateral subungual onychomycosis and in 1 case like total dystrophic onychomycosis. Five cases (27.78%) were associated with hypertension, diabetes, and psoriasis. Treatment with terbinafine or itraconazole was effective. Two cases of M. canis distal lateral subungual onychomycosis responded to photodynamic therapy.

Conclusion: This is the largest reported series of Microsporum onychomycosis and demonstrates such a disease in an urban population. In 27.78% of the cases risk factors for infection were associated to comorbid states. We also report the first 2 cases of successfully treated M. canis onychomycosis with photodynamic therapy and a rare case of M. canis associated dermatophytoma.

Keywords: Dermatophytes; Microsporum; Onychomycosis.

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Figures

Fig. 1
Fig. 1
Culture of Microsporum nanum on Sabouraud dextrose agar with chloramphenicol.
Fig. 2
Fig. 2
Microsporum nanum macroconidia on lactophenol blue stain. 40×.
Fig. 3
Fig. 3
Total dystrophic onychomycosis due to Microsporum nanum.
See this image and copyright information in PMC

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