MICROBIOLOGY

• T. marneffei is a thermally dimorphic fungus, previously named Penicilliummarneffei.
  • At room temperature, 25^oC, the mold form produces yellowish green colonies with diffusing red pigment.[8]
  • At 37^oC, colonies are cerebriform, smooth, light tan, and creamy.
    • Yeast forms are 3-6 x 2 µm, sausage-shaped with central transverse septum and divide by fission.
• T. marneffei is geographically distributed across tropical SE Asia. Talaromycosis, previously called penicilliosis, is endemic in northeastern India, northern Thailand, Vietnam, Myanmar, Laos, Cambodia, Indonesia, Hong Kong, southern China.[5]
• Transmission occurs primarily via inhalation; also by direct inoculation and possibly by ingestion.
• The animal reservoir is the wild bamboo rat, which lives in highland areas. The incidence of infection increases during the rainy season due to increased humidity and expansion of the environmental reservoir.[2]
  • T. marneffei has been isolated from 100% of samples cultured from lungs, liver, and spleens of hoary bamboo rats in Guangxi Province, China.[21]
  • Organism is also isolated from the soil of bamboo rats’ burrows.
• The fungus proliferates in macrophages and spreads via the reticuloendothelial system.[11]