Infectious Disease Online
Pathology of Penicilliosis (Penicillium Marneffei Infection)
Penicilliosis is caused by Penicillium marneffei, a ubiquitous saprophyte of soil and decomposing organic matter.
A disseminated and progressive infection, penicilliosis marneffei is the third most common opportunistic fungal infection in human immunodeficiency virus (HIV)-infected patients in certain parts of Southeast Asia.
Penicillium marneffei is endemic in Southeast Asia and Far East Asia, particularly in the southern part of China. Cases have been reported from both Eastern and Western countries. The first documented human case was a laboratory acquired disease in France in 1959.
Of the more than 150 recognized species of Penicillium, only Penicillium marneffei is known to be dimorphic and to cause invasive infection.
Prior to the epidemic of human immunodeficiency virus (HIV), penicilliosis was a rare event.
The incidence of this fungal infection has increased markedly during the past few years, paralleling the incidence of HIV infection.
Mode of infection:
Most human infections probably have a pulmonary inception after inhalation of airborne infectious conidia of Penicillium marneffei produced in the environment.
Persons who are debilitated or immunocompromised appear to be at increased risk of infection.
Patients with disseminated penicilliosis marneffei often present with chronic productive cough, mucoid sputum, chest pain, generalized lymphadenopathy , hepato-splenomegaly, draining skin ulcers, subcutaneous abscesses, osteolytic lesions, anemia, leukocytosis and a history of weight loss and prolonged intermittent fever.
The skin lesions are most commonly papules with central necrotic umbilication.
Course of the disease :
The course of the disease can range from 2 months to 3 years or more.
Organs involved: Organs most frequently involved include the lungs, liver, intestine, lymph nodes, tonsils, skin, bone marrow, kidneys, and spleen.
The host response in penicilliosis marneffei is similar to that seen in histoplasmosis , where numerous small yeast-like cells proliferate within and distend histiocytes.
Slowly evolving pulmonary abscesses and granulomas can lead to fibrosis and cavitation, but calcification has not been reported.
In histologic sections, the cells of Penicillium marneffei are spherical to oval, 2.5 to 5 micrometer in diameter, and resemble those of Histoplasma capsulatum.
However, unlike histoplasma and other invasive yeast-like fungi, Penicillium marneffei does not bud.
Reproduction is by fission (schizogony) with the formation of a single transverse septum that stains more intensely with the special stains for fungi and is wider than the external wall.
Short hyphal forms and elongated, curved sausage-like forms with rounded ends and one or more septa are also occasionally produced, especially in the necrotic and cavitary lesions.
Diagnosis: A definitive diagnosis of penicilliosis marneffei can be made by demonstration of typical yeast-like cells in clinical specimens and by microbiologic culture an standard mycologic media.
Treatment: The mycosis must be aggressively treated with amphotericin B, 5-fluorocytosine, or keratoconazole.
Because relapse is common, antifungals should be given for several months.
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