Penicillium marneffei LPCB preparation is showing conidiophores those are hyaline, smooth walled and bear terminal verticils or whorls of 3-5 metulae, each bearing 3-5 phialides. The conidiophores are described as biverticillate or irregularly monoverticillate. Conidia are globose to subglobose, 2-3 µm in diameter, smooth-walled and are produced in basipetal succession from the phialides.
Penicillium marneffei exhibits thermal dimorphism by growing in living tissue or in culture at 37°C as a yeast-like fungus, and in culture at below 30°C as a mould. On SDA (without cycloheximide) at 25°C colonies are fast-growing, suedelike to downy, white with yellowish-green conidial heads. Colonies become grayish-pink to brown with age and produce a characteristic diffusible brownishred to wine-red pigment
Penicillium marneffei, the dimorphic fungus causes the disease, which is an
emerging systemic mycosis in AIDS patients as well as other immunocompromized patients. P. marneffei is endemic in Thailand, Northeastern India, southern China, Hong Kong, Vietnam and Taiwan in AIDS patients. Bamboo rats and soil are considered the reservoir of the disease though the causative agent has never been isolated from soil except near bamboo rat burrows. P. marneffei, after tuberculosis and cryptococcosis, is the third most common opportunistic infection in patients with AIDS in the South-East Asia Region, and is therefore considered an AIDS-defining illness. People affected by penicilliosis usually have AIDS with low CD4 counts, typically <100/µl.
Various types of manifestations include:
pyrexia ( fever) of unknown origin (PUO), loss of weight, generalized
hepatomegaly with or without splenomegaly
pneumonitis: cough and dyspnea occur in about 50% of cases,
sometimes with hemoptysis
Laboratory manual for diagnosis of fungal opportunistic infections in HIV/AIDS patients
skin lesions – characteristic generalized papular eruptions, central
umbilicated papules resembling those of molluscum contagiosum, or acne like lesions and folliculitis over face, trunk, and extremities
pharyngeal and palatal lesions also can be seen subcutaneous nodules may be seen
chest radiographic abnormalities typically manifest as diffuse reticulonodular infiltrates, and cavitations
Giemsa, Wright, GMS or PAS stain shows characteristic intracellular (within neutrophils or tissue histiocytes) round to oval yeast-like cells, which may divide by cross wall formation. The cross wall formation can differentiate yeast cell of P. marneffei from those of Histoplasma capsulatum. Elongated sausageshaped extracellular forms are also seen.
Direct immuno-fluorescence test is the test of choice for specific diagnosis; this would be done at reference laboratories, since it requires a fluorescent microscope.
Definitive diagnosis is based on culture isolation, which has a high sensitivity – bone marrow (100%), blood (76%) and skin biopsies (90%). Penicillium marneffei exhibits thermal dimorphism by growing in living tissue or in culture at 37°C as a yeast-like fungus, and in culture at below 30°C as a mold.
Several serological methods for detection of antibodies or antigens are attempted and produce conflicting results especially in AIDS patients. e.g. commercially available Pastorex Aspergillus i.e. Latex Agglutination test kit
A specific PCR assay is under evaluation and might be useful as an alternative test for rapid diagnosis of Penicillium marneffei infection.
Useful anti-fungal drugs are-
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