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speciation does not influence therapy. Treatment includes surgical debridement of involved
areas where accessible and amphotericin B.[533]
PENICILLIOSIS.-- Infections with Penicillium marneffei are seen in HIV-infected
persons living in Southeast Asia, the southern part of China, the Philippines, and Indonesia.
Most infected persons will have a CD4 lymphocyte count below 100/µL. Exposure to soils,
particularly in the rainy season, appears to be a risk factor. Infections tend to be disseminated.
Clinical findings may include intermittent fever with or without chills, skin lesions, malaise,
chronic productive cough, pulmonary infiltrates, anemia, hepatosplenomegaly, generalized
lymphadenopathy, diarrhea, and weight loss. About two-thirds of patients will have skin lesions
that may be the first sign of infection. The lesions are most frequent on the face, upper trunk, and
extremities. The lesions may occur as papules, a generalized papular rash, necrotic papules, or
nodules. Papules with central necrotic umbilication may resemble lesions of molluscum
contagiosum. The skin lesions may resemble those of disseminated mycobacterial or fungal
diseases.[453,534,535]
Diagnosis can be made via culture of blood. About half of patients will have a
septicemia. Culture of tissues from affected sites can be performed, with the best yield from
bone marrow, skin scraping, or lymph node biopsy. At autopsy, the most common sites of
involvement are lymph nodes, liver, lung, kidney, and bone marrow.[534,535,536]
P marneffei is found in the mycelial form in the environment, but it grows as a small
spherical to oval 3 to 8 micron yeast form in tissues and appears very similar to, but slightly
larger than, H capsulatum, and slightly smaller than P jiroveci (carinii) in size with the Gomori
methenamine silver (GMS) and periodic acid-Schiff (PAS) stains. Organisms are often abundant
both intracellularly and extracellularly. The yeast form of the organism may be found both
intracellularly within macrophages, and also in the extracellular environment. However, the
small size of the organisms may cause confusion with cellular debris. The yeast cells resemble
the spores of H capsulatum but the distinctive central transverse septum is unique to P marneffei.
In addition, H capsulatum undergoes division by budding while P marneffei uses a process of
"fission" to generate a septum and produce daughter cells. Toxoplasma tachyzoites do not bud or
produce septae.[537]
Microscopically in immunocompetent hosts, there is typically a granulomatous reaction
or a localized abscess. However, in immunocompromised hosts the tissue reaction includes
necrosis without granuloma formation, and the predominant cell present is a macrophage
engorged with the yeasts. Treatment may consist of itraconazole, ketoconazole, flucytosine, or
amphotericin B. Most patients respond to initial therapy, but the relapse rate approaches
50%.[454,534,536]
SPOROTRICHOSIS.-- Infection with the dimorphic fungus Sporothrix schenckii, which
has a worldwide distribution, is most commonly cutaneous from traumatic inoculation, with
lesions that appear most often on the face, trunk, and extremities. Exposure to cats, with biting
and scratching, is a risk factor. The lymphocutaneous form of the disease accounts for over 75%
of all cases and is characterized by the emergence of a 2 to 4 cm indurated papule that develops
about 7 to 30 days after inoculation of the fungus into the skin. Progressive induration leads to
nodule formation with subsequent ulceration and crusting. Additional nodules appear in the
lymphatic drainage from the site of inoculation. The lesions may soften and produce cutaneous
fistulae. On microscopic examination, the lesions show granulomatous inflammation with