Mould infections

Mould infections can occasionally infect the skin and nails and cause indolent infections in healthy or immune compromised individuals, especially the elderly. Mould infections originate from soil.

The responsible organisms include:

• Scopulariopsis brevicaulis
• Fusarium spp.
• Aspergillus spp.
• Alternaria spp.
• Acremonium spp.
• Scytalidinum dimidiatum (Hendersonula toruloides)
• Scytalidinium hyalinum

Mould infections

Aspergillus

Aspergillus

Fusarium

Clinical features

Mould infections can complicate athlete's foot and appear identical to tinea pedis. They can be mild or severe. Scopulariopsis brevicaulis and Scytalidinum dimidiatum are the most likely moulds to present as skin infection.

Mould infections of the finger and toenails can be indistinguishable from other types of onychomycosis. However, unlike dermatophyte infections, moulds frequently result in paronychia (inflamed nail folds). One or more toenails may be infected, or the mould may simply be a contaminant. The surrounding skin is often dry and may itch. The appearance of the nail may include:

• Brownish dull discolouration of the nail, which starts at one edge
• Streaked and pitted nail plate
• Complete nail destruction.

Diagnosis

Mould infections are diagnosed by microscopy and culture of skin scrapings and/or nail clippings (mycology tests). Culture of moulds is identical to that of dermatophyte fungi except that the antiseptic actidione (cycloheximide) should be left out of the medium.

The infection may be indistinguishable from tinea unguium before mycology has been performed. Sometimes the nails are co- infected by a dermatophyte fungus. If this is so, the laboratory may initially consider the mould a contaminant and fail to report its presence.

Some mould infections are due to dematiaceous fungi (coloured brown) giving rise to phaeohyphomycosis.

Potassium hydroxide examination

Hendersonula

Treatment

Mould nail infections are notoriously difficult to clear with currently available medications, which may be required for longer courses or in combination with other topical and oral antifungal agents.

Cures have been most frequently reported with a combination of:

• Removal of the infected nail, surgically or with chemicals
• Topical antifungal nail lacquer or solution
• Oral itraconazole &/or terbinafine