Deep fungal infections comprise 2 distinct groups of conditions: subcutaneous mycoses and systemic mycoses. Neither are common, and the subcutaneous mycoses, with some exceptions, are largely confined to the tropics and subtropics. In recent years, the systemic mycoses have become important opportunistic infectious complications in immunocompromised patients, including those with AIDS and patients receiving treatment for malignancies. They also include a group of primary respiratory tract infections, such as histoplasmosis and coccidioidomycosis, which may affect otherwise healthy individuals and those with underlying illness. The fungi that cause these respiratory tract infections are usually dimorphic or exist in a different morphologic phase (eg, yeast or mold) at different stages of their life cycle.
Patients with subcutaneous fungal infections often present to a physician with signs of skin involvement. By contrast, patients with systemic mycoses only occasionally have skin lesions, either following direct involvement of the skin as a portal of entry or after dissemination from a deep focus of infection. There are a number of excellent texts about fungi and the diseases they cause.1-4
Treatment of these conditions remains difficult in many cases, although there is now a wide range of antifungal drugs with different modes of action.
Are usually sporadic.
Are contracted in the tropics and subtropics.
May cause chronic disability.
Are best diagnosed by histopathology, except for sporotrichosis.
Often require months of successful antifungal treatment.
The subcutaneous mycoses (Table 162-1), or mycoses of implantation, are infections caused by fungi that have been introduced directly into the dermis or subcutaneous tissue through a penetrating injury, such as a thorn prick. Although many are tropical infections, others, such as sporotrichosis, are also prevalent in temperate climates; any of these infections may present as an imported disease in a patient who has originated from an endemic area, sometimes after a lapse of many years. The most common subcutaneous mycoses are sporotrichosis, mycetoma, and chromoblastomycosis. Rarer infections include lobomycosis and subcutaneous mucormycosis.
TABLE 162-1Summary of Subcutaneous Mycoses ||Download (.pdf) TABLE 162-1 Summary of Subcutaneous Mycoses
|SUBCUTANEOUS MYCOSES ||CAUSATIVE AGENTS ||EPIDEMIOLOGY ||CLINICAL FEATURES ||HISTOPATHOLOGY ||TREATMENT |
|Sporotrichosis || |
|North, South, Central Americas, including southern United States and Mexico, Africa, Egypt, Japan, Australia || |
Lymphangitic: dermal nodules that break down into small ulcers in linear pattern
Fixed: localized to one site, with granuloma formation and ulceration
Mixed granulomatous reaction with neutrophilic microabscesses
Fungus is 3 to 5 µm, cigar-shaped or oval
Distinctive asteroid body
Itraconazole 200 mg once daily
Terbinafine 250 mg once daily
treatment continued until 1 week after clinical resolution
Saturated solution of potassium iodide (SSKI), 4 to 6 mL thrice daily × 3 to 12 weeks
|Mycetoma (maduromycosis, Madura foot) || |
Filamentous bacteria (actinomycetoma): Nocardia...